Does a surgical (non-N95) mask reduce the risk of contracting viruses that cause respiratory disease?

Submitted by: ELee 65

Yes. The vast majority of studies in this list came to this conclusion. Note that some of the studies in this list have been commented on or critiqued. Links to these comments/critiques appear on the corresponding study summaries below.
NOTE: New research on COVID-19 comes out nearly every day. The state of our knowledge may change quickly so take this answer with a grain of salt.
This short answer was generated by aggregating the answers that each of the 24 studies below gave to the question (as indicated by State of K members) and adjusting for source quality and other factors. If key studies are missing or the answers attributed to individual studies are incorrect, the above answer could be wrong. For medical questions, don't rely on the information here. Consult a medical professional.


Chart summary of 24 studies examining this question
Showing up to 10 at a time

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All labels of Literature Reviews and source quality are assigned by State of K. For academic journals, the label "Q[NUMBER]" is an indication of the quality of the publication. The "NUMBER" refer to the best quartile in which the journal appeared among all the subjects in which the journal was ranked by Scimago Institutions Rankings. For example, if a journal was ranked in the third quartile (Q3) in infectious diseases, but in the second quartile in Ebola studies (Q2), you would see "Q2". The best quartile is "Q1". Publications other than academic journals may be labeled as "Highly Regarded Sources". Government sources receive this label as do NGOs ranked by the TTCSP Global Go To Think Tank Index Reports. The information contained in a source that is labeled "highly regarded" or "Q1" is not necessarily more accurate than information contained in a source without that label, but these are rough guides to source quality.

Literature Reviews
Although we recommend you consider all of the studies below, we believe the following studies are literature reviews, which survey and evaluate many studies on this question:
Additional Recommended Studies Not in this List (yet)

QUESTIONS TO CONSIDER
Are cloth masks as effective as surgical masks at reducing the risk of contracting viruses that cause respiratory disease?
6 studies
Submitted by: MChoi 148

Can you contract COVID-19 twice?
5 studies
Submitted by: JAloni 117

Do adults get sick from COVID-19 more often than children?
10 studies
Submitted by: JLjilijana 85

Do cloth masks reduce the risk of contracting viruses that cause respiratory disease?
10 studies
Submitted by: JAloni 117

Does air pollution accelerate the spread of COVID-19?
7 studies
Submitted by: JLjilijana 85

Does air pollution increase the severity of symptoms from COVID-19?
6 studies
Submitted by: KKrista 83

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SUMMARIES OF STUDIES
Total studies in list: 24 showing 20 studies at a time
Sorted by publication year
1
Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis
"BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 and is spread person-to-person through close contact. We aimed to investigate the effects of physical distance, face masks, and eye protection on virus transmission in health-care and non-health-care (eg, community) settings.MethodsWe did a systematic review and meta-analysis to investigate the optimum distance for avoiding person-to-person virus transmission and to assess the use of face masks and eye protection to prevent transmission of viruses. We obtained data for SARS-CoV-2 and the betacoronaviruses that cause severe acute respiratory syndrome, and Middle East respiratory syndrome from 21 standard WHO-specific and COVID-19-specific sources. We searched these data sources from database inception to May 3, 2020, with no restriction by language, for comparative studies and for contextual factors of acceptability, feasibility, resource use, and equity. We screened records, extracted data, and assessed risk of bias in duplicate. We did frequentist and Bayesian meta-analyses and random-effects meta-regressions. We rated the certainty of evidence according to Cochrane methods and the GRADE approach. This study is registered with PROSPERO, CRD42020177047.FindingsOur search identified 172 observational studies across 16 countries and six continents, with no randomised controlled trials and 44 relevant comparative studies in health-care and non-health-care settings (n=25 697 patients). Transmission of viruses was lower with physical distancing of 1 m or more, compared with a distance of less than 1 m (n=10 736, pooled adjusted odds ratio [aOR] 0·18, 95% CI 0·09 to 0·38; risk difference [RD] −10·2%, 95% CI −11·5 to −7·5; moderate certainty); protection was increased as distance was lengthened (change in relative risk [RR] 2·02 per m; pinteraction=0·041; moderate certainty). Face mask use could result in a large reduction in risk of infection (n=2647; aOR 0·15, 95% CI 0·07 to 0·34, RD −14·3%, −15·9 to −10·7; low certainty), with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar (eg, reusable 12–16-layer cotton masks; pinteraction=0·090; posterior probability >95%, low certainty). Eye protection also was associated with less infection (n=3713; aOR 0·22, 95% CI 0·12 to 0·39, RD −10·6%, 95% CI −12·5 to −7·7; low certainty). Unadjusted studies and subgroup and sensitivity analyses showed similar findings.InterpretationThe findings of this systematic review and meta-analysis support physical distancing of 1 m or more and provide quantitative estimates for models and contact tracing to inform policy. Optimum use of face masks, respirators, and eye protection in public and health-care settings should be informed by these findings and contextual factors. Robust randomised trials are needed to better inform the evidence for these interventions, but this systematic appraisal of currently best available evidence migh"
AUTHORS
Sally Yaacoub
Karla Solo
Stephanie Duda
Elie A Akl
Derek K Chu
Chen Chen et al
PUBLISHED
2020 in The Lancet
High quality source
Literature Review
Yes
Yes
2
Respiratory Virus Shedding in Exhaled Breath and Efficacy of Face Masks
"Abstract There are few studies describing the presence of respiratory viruses in respiratory droplets and aerosols in the exhaled breath of infected persons, and the efficacy of facemasks as a source control to prevent respiratory virus transmission. Here, we recruited children and adults with acute respiratory illness and collected respiratory droplets and aerosols, with and without surgical facemasks. We identified human coronaviruses, influenza virus and rhinovirus from both respiratory droplets and aerosols. Surgical face masks reduced detection of coronavirus RNA in both respiratory droplets and aerosols, but only respiratory droplets and not aerosols for influenza virus RNA. Our results provide mechanistic evidence that surgical facemasks could prevent transmission of human coronavirus and influenza virus infections if worn by symptomatic individuals.Authors Donald K Milton and Benjamin J Cowling are joint senior authors. "
AUTHORS
James J McDevitt
Benien JP Hau
Gabriel M Leung
Donald K Milton
Nancy HL Leung
Hui-Ling Yen et al
PUBLISHED
2020 in Research Square
UNRANKED SOURCE
Yes
Yes
3
The use of facemasks by the general population to prevent transmission of Covid 19 infection: A systematic review.
"BackgroundThe pandemic of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2), has become a serious worldwide public health emergency. This systematic review aims to summarize the available evidence regarding the role of face mask in community settings in slowing the spread of respiratory viruses such as SARS- CoV-2. MethodsThe preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used for this review. A literature search using PUBMED, Google Scholar, and Cochrane database were performed using Medical subject heading (MeSH) words from the year 2000-2020. The articles focused on the use of masks and N95 respirators in healthcare workers were excluded.ResultsA total of 305 records were identified, out of which 14 articles were included in the review based upon quality and eligibility criteria. All the articles mentioned about the role of face masks in preventing the spread of respiratory viruses like influenza, SARS, and SARS-CoV-2, in the community or experimental setting. Studies also suggested that early initiation of face mask usage was more effective. Masks were also reported to be more effective in viruses that transmit easily from asymptomatic individuals, as is now known in SARS-CoV-2. ConclusionTheoretical, experimental, and clinical evidence suggested that usage of face masks in a general population offered significant benefit in preventing the spread of respiratory viruses especially in the pandemic situation, but its utility is limited by inconsistent adherence to mask usage."
AUTHORS
Sarika Gupta
Khushi Gupta
MADHU GUPTA
PUBLISHED
2020 in Cold Spring Harbor Laboratory
Literature Review
Yes
Yes
4
Effectiveness of masks and respirators against respiratory infections in healthcare workers: a systematic review and meta-analysis
"This systematic review and meta-analysis quantified the protective effect of facemasks and respirators against respiratory infections among healthcare workers. Relevant articles were retrieved from Pubmed, EMBASE, and Web of Science. Meta-analyses were conducted to calculate pooled estimates. Meta-analysis of randomized controlled trials (RCTs) indicated a protective effect of masks and respirators against clinical respiratory illness (CRI) (risk ratio [RR] = 0.59; 95% confidence interval [CI]:0.46-0.77) and influenza-like illness (ILI) (RR = 0.34; 95% CI:0.14-0.82). Compared to masks, N95 respirators conferred superior protection against CRI (RR = 0.47; 95% CI: 0.36-0.62) and laboratory-confirmed bacterial (RR = 0.46; 95% CI: 0.34-0.62), but not viral infections or ILI. Meta-analysis of observational studies provided evidence of a protective effect of masks (OR = 0.13; 95% CI: 0.03-0.62) and respirators (OR = 0.12; 95% CI: 0.06-0.26) against severe acute respiratory syndrome (SARS). This systematic review and meta-analysis supports the use of respiratory protection. However, the existing evidence is sparse and findings are inconsistent within and across studies. Multicentre RCTs with standardized protocols conducted outside epidemic periods would help to clarify the circumstances under which the use of masks or respirators is most warranted."
AUTHORS
Chee Fu Yung
Clarence C Tam
Vittoria Offeddu
Mabel Sheau Fong Low
PUBLISHED
2017 in Clinical Infectious Diseases
High quality source
Literature Review
Yes
Yes
5
Facemasks for the prevention of infection in healthcare and community settings
"Facemasks are recommended for diseases transmitted through droplets and respirators for respiratory aerosols, yet recommendations and terminology vary between guidelines. The concepts of droplet and airborne transmission that are entrenched in clinical practice have recently been shown to be more complex than previously thought. Several randomised clinical trials of facemasks have been conducted in community and healthcare settings, using widely varying interventions, including mixed interventions (such as masks and handwashing), and diverse outcomes. Of the nine trials of facemasks identified in community settings, in all but one, facemasks were used for respiratory protection of well people. They found that facemasks and facemasks plus hand hygiene may prevent infection in community settings, subject to early use and compliance. Two trials in healthcare workers favoured respirators for clinical respiratory illness. The use of reusable cloth masks is widespread globally, particularly in Asia, which is an important region for emerging infections, but there is no clinical research to inform their use and most policies offer no guidance on them. Health economic analyses of facemasks are scarce and the few published cost effectiveness models do not use clinical efficacy data. The lack of research on facemasks and respirators is reflected in varied and sometimes conflicting policies and guidelines. Further research should focus on examining the efficacy of facemasks against specific infectious threats such as influenza and tuberculosis, assessing the efficacy of cloth masks, investigating common practices such as reuse of masks, assessing compliance, filling in policy gaps, and obtaining cost effectiveness data using clinical efficacy estimates. "
AUTHORS
A. A. Chughtai
C. R. MacIntyre
PUBLISHED
2015 in BMJ
High quality source
Yes
Yes
6
Non-pharmaceutical interventions for the prevention of respiratory tract infections during Hajj pilgrimage
"Overcrowding during the yearly Hajj mass gatherings is associated with increased risk of spreading infectious diseases, particularly respiratory diseases. Non-pharmaceutical interventions (e.g., hand hygiene, wearing face masks, social distancing) are known to reduce the spread of respiratory viruses from person to person and are therefore recommended to pilgrims by public health agencies. The implementation of effective public health policies and recommendations involves evaluating the adherence to and effectiveness of these measures in the specific context of the Hajj. This review summarizes the evidence related to the effectiveness of non-pharmaceutical interventions in preventing the spread of respiratory infectious diseases during the Hajj. Overall, although hand hygiene compliance is high among pilgrims, face mask use and social distancing remain difficult challenges. Data about the effectiveness of these measures at the Hajj are limited, and results are contradictory, highlighting the need for future large-scale studies. "
AUTHORS
Philippe Brouqui
Samir Benkouiten
Philippe Gautret
PUBLISHED
2014 in Travel Medicine and Infectious Disease
High quality source
Couldn't Identify
Couldn't Identify
7
AUTHORS
Sergey A. Grinshpun
Tiina Reponen
Xinjian He
Roy T. McKay
PUBLISHED
2013 in Aerosol Science and Technology
Q2
Couldn't Identify
Couldn't Identify
8
Protection by face masks against influenza A(H1N1)pdm09 virus on trans-Pacific passenger aircraft, 2009.
"In response to several influenza A(H1N1)pdm09 infections that developed in passengers after they traveled on the same 2 flights from New York, New York, USA, to Hong Kong, China, to Fuzhou, China, we assessed transmission of influenza A(H1N1)pdm09 virus on these flights. We defined a case of infection as onset of fever and respiratory symptoms and detection of virus by PCR in a passenger or crew member of either flight. Illness developed only in passengers who traveled on the New York to Hong Kong flight. We compared exposures of 9 case-passengers with those of 32 asymptomatic control-passengers. None of the 9 case-passengers, compared with 47% (15/32) of control-passengers, wore a face mask for the entire flight (odds ratio 0, 95% CI 0-0.71). The source case-passenger was not identified. Wearing a face mask was a protective factor against influenza infection. We recommend a more comprehensive intervention study to accurately estimate this effect."
AUTHORS
Marc-Alain Widdowson
Tao Shen
Yunxia Feng
Hang Zhou
Jianming Ou
Fuqiang Cui et al
PUBLISHED
2013 in Emerging Infectious Diseases
High quality source
Yes
Yes
9
Respiratory and facial protection: a critical review of recent literature
"Infectious micro-organisms may be transmitted by a variety of routes. This is dependent on the particular pathogen and includes bloodborne, droplet, airborne, and contact transmission. Some micro-organisms are spread by more than one route. Respiratory and facial protection is required for those organisms which are usually transmitted via the droplet and/or airborne routes or when airborne particles have been created during 'aerosol-generating procedures'. This article presents a critical review of the recently published literature in this area that was undertaken by Health Protection Scotland and the Healthcare Infection Society and which informed the development of guidance on the use of respiratory and facial protection equipment by healthcare workers. "
AUTHORS
D. Bunyan
D. Jenkins
L. Ritchie
J.E. Coia
PUBLISHED
2013 in Journal of Hospital Infection
High quality source
Couldn't Identify
Couldn't Identify
10
Effectiveness of surgical masks against influenza bioaerosols
"Background: Most surgical masks are not certified for use as respiratory protective devices (RPDs). In the event of an influenza pandemic, logistical and practical implications such as storage and fit testing will restrict the use of RPDs to certain high-risk procedures that are likely to generate large amounts of infectious bioaerosols. Studies have shown that in such circumstances increased numbers of surgical masks are worn, but the protection afforded to the wearer by a surgical mask against infectious aerosols is not well understood.Aim: To develop and apply a method for assessing the protection afforded by surgical masks against a bioaerosol challenge.Methods: A dummy test head attached to a breathing simulator was used to test the performance of surgical masks against a viral challenge. Several designs of surgical masks commonly used in the UK healthcare sector were evaluated by measuring levels of inert particles and live aerosolised influenza virus in the air, from in front of and behind each mask.Findings: Live influenza virus was measurable from the air behind all surgical masks tested. The data indicate that a surgical mask will reduce exposure to aerosolised infectious influenza virus; reductions ranged from 1.1- to 55-fold (average 6-fold), depending on the design of the mask.Conclusion: We describe a workable method to evaluate the protective efficacy of surgical masks and RPDs against a relevant aerosolised biological challenge. The results demonstrated limitations of surgical masks in this context, although they are to some extent protective."
AUTHORS
C. Makison Booth
J.M. Gawn
B. Crook
M. Clayton
PUBLISHED
2013 in Journal of Hospital Infection
High quality source
Yes
Yes
11
Physical interventions to interrupt or reduce the spread of respiratory viruses.
"Background: Viral epidemics or pandemics of acute respiratory infections like influenza or severe acute respiratory syndrome pose a global threat. Antiviral drugs and vaccinations may be insufficient to prevent their spread.Objectives: To review the effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.Search Strategy: We searched The Cochrane Library, the Cochrane Central Register of Controlled Trials (CENTRAL 2010, Issue 3), which includes the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to October 2010), OLDMEDLINE (1950 to 1965), EMBASE (1990 to October 2010), CINAHL (1982 to October 2010), LILACS (2008 to October 2010), Indian MEDLARS (2008 to October 2010) and IMSEAR (2008 to October 2010).Selection Criteria: In this update, two review authors independently applied the inclusion criteria to all identified and retrieved articles and extracted data. We scanned 3775 titles, excluded 3560 and retrieved full papers of 215 studies, to include 66 papers of 67 studies. We included physical interventions (screening at entry ports, isolation, quarantine, social distancing, barriers, personal protection, hand hygiene) to prevent respiratory virus transmission. We included randomised controlled trials (RCTs), cohorts, case-controls, before-after and time series studies.Data Collection And Analysis: We used a standardised form to assess trial eligibility. We assessed RCTs by randomisation method, allocation generation, concealment, blinding and follow up. We assessed non-RCTs for potential confounders and classified them as low, medium and high risk of bias.Main Results: We included 67 studies including randomised controlled trials and observational studies with a mixed risk of bias. A total number of participants is not included as the total would be made up of a heterogenous set of observations (participant people, observations on participants and countries (object of some studies)). The risk of bias for five RCTs and most cluster-RCTs was high. Observational studies were of mixed quality. Only case-control data were sufficiently homogeneous to allow meta-analysis. The highest quality cluster-RCTs suggest respiratory virus spread can be prevented by hygienic measures, such as handwashing, especially around younger children. Benefit from reduced transmission from children to household members is broadly supported also in other study designs where the potential for confounding is greater. Nine case-control studies suggested implementing transmission barriers, isolation and hygienic measures are effective at containing respiratory virus epidemics. Surgical masks or N95 respirators were the most consistent and comprehensive supportive measures. N95 respirators were non-inferior to simple surgical masks but more expensive, uncomfortable and irritating to skin. Adding virucidals or antiseptics to normal handwashing to decrease respiratory disease transmission remains uncertain. Global measures, such as screening at entry ports, led to a non-significant marginal delay in spread. There was limited evidence that social distancing was effective, especially if related to the risk of exposure.Authors' Conclusions: Simple and low-cost interventions would be useful for reducing transmission of epidemic respiratory viruses. Routine long-term implementation of some measures assessed might be difficult without the threat of an epidemic."
AUTHORS
Ghada A Bawazeer
Sreekumaran Nair
Mark A Jones
Liz Dooley
Chris B Del Mar
Tom Jefferson et al
PUBLISHED
2011 in The Cochrane Database of Systematic Reviews
High quality source
Literature Review
Yes
Yes
12
Mask Use, Hand Hygiene, and Seasonal Influenza‐Like Illness among Young Adults: A Randomized Intervention Trial
"Background: During the influenza A(H1N1) pandemic, antiviral prescribing was limited, vaccines were not available early, and the effectiveness of nonpharmaceutical interventions (NPIs) was uncertain. Our study examined whether use of face masks and hand hygiene reduced the incidence of influenza-like illness (ILI).Methods: A randomized intervention trial involving 1437 young adults living in university residence halls during the 2006-2007 influenza season was designed. Residence halls were randomly assigned to 1 of 3 groups-face mask use, face masks with hand hygiene, or control- for 6 weeks. Generalized models estimated rate ratios for clinically diagnosed or survey-reported ILI weekly and cumulatively.Results: We observed significant reductions in ILI during weeks 4-6 in the mask and hand hygiene group, compared with the control group, ranging from 35% (confidence interval [CI], 9%-53%) to 51% (CI, 13%-73%), after adjusting for vaccination and other covariates. Face mask use alone showed a similar reduction in ILI compared with the control group, but adjusted estimates were not statistically significant. Neither face mask use and hand hygiene nor face mask use alone was associated with a significant reduction in the rate of ILI cumulatively.Conclusions: These findings suggest that face masks and hand hygiene may reduce respiratory illnesses in shared living settings and mitigate the impact of the influenza A(H1N1) pandemic.Trial Registration: ClinicalTrials.gov identifier: NCT00490633."
AUTHORS
David K. Shay
Monica Uddin
Vanessa Perez
Allison E. Aiello
Genevra F. Murray
Rebecca M. Coulborn et al
PUBLISHED
2010 in The Journal of Infectious Diseases
High quality source
Yes
Yes
13
A Quantitative Assessment of the Efficacy of Surgical and N95 Masks to Filter Influenza Virus in Patients with Acute Influenza Infection
"We assessed the in vivo efficacy of surgical and N95 (respirator) masks to filter reverse transcription-polymerase chain reaction (RT-PCR)-detectable virus when worn correctly by patients with laboratory-confirmed acute influenza. Of 26 patients with a clinical diagnosis of influenza, 19 had the diagnosis confirmed by RT-PCR, and 9 went on to complete the study. Surgical and N95 masks were equally effective in preventing the spread of PCR-detectable influenza."
AUTHORS
M. L. Grayson
C. Birch
J. D. Druce
D. F. Johnson
PUBLISHED
Yes
Yes
14
Face mask use and control of respiratory virus transmission in households.
"Many countries are stockpiling face masks for use as a nonpharmaceutical intervention to control virus transmission during an influenza pandemic. We conducted a prospective cluster-randomized trial comparing surgical masks, non-fit-tested P2 masks, and no masks in prevention of influenza-like illness (ILI) in households. Mask use adherence was self-reported. During the 2006 and 2007 winter seasons, 286 exposed adults from 143 households who had been exposed to a child with clinical respiratory illness were recruited. We found that adherence to mask use significantly reduced the risk for ILI-associated infection, but <50% of participants wore masks most of the time. We concluded that household use of face masks is associated with low adherence and is ineffective for controlling seasonal respiratory disease. However, during a severe pandemic when use of face masks might be greater, pandemic transmission in households could be reduced."
AUTHORS
Zhanhai Gao
Holly Seale
Simon Cauchemez
Dominic E Dwyer
James Wood
Neil Ferguson et al
PUBLISHED
2009 in Emerging Infectious Diseases
High quality source
Yes
Yes
15
Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review.
"Objective: To review systematically the evidence of effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.Data Sources: Cochrane Library, Medline, OldMedline, Embase, and CINAHL, without restrictions on language or publication. Data selection Studies of any intervention to prevent the transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection, and hygiene). A search of study designs included randomised trials, cohort, case-control, crossover, before and after, and time series studies. After scanning of the titles, abstracts and full text articles as a first filter, a standardised form was used to assess the eligibility of the remainder. Risk of bias of randomised studies was assessed for generation of the allocation sequence, allocation concealment, blinding, and follow-up. Non-randomised studies were assessed for the presence of potential confounders and classified as being at low, medium, or high risk of bias.Data Synthesis: 58 papers of 59 studies were included. The quality of the studies was poor for all four randomised controlled trials and most cluster randomised controlled trials; the observational studies were of mixed quality. Meta-analysis of six case-control studies suggested that physical measures are highly effective in preventing the spread of severe acute respiratory syndrome: handwashing more than 10 times daily (odds ratio 0.45, 95% confidence interval 0.36 to 0.57; number needed to treat=4, 95% confidence interval 3.65 to 5.52), wearing masks (0.32, 0.25 to 0.40; NNT=6, 4.54 to 8.03), wearing N95 masks (0.09, 0.03 to 0.30; NNT=3, 2.37 to 4.06), wearing gloves (0.43, 0.29 to 0.65; NNT=5, 4.15 to 15.41), wearing gowns (0.23, 0.14 to 0.37; NNT=5, 3.37 to 7.12), and handwashing, masks, gloves, and gowns combined (0.09, 0.02 to 0.35; NNT=3, 2.66 to 4.97). The combination was also effective in interrupting the spread of influenza within households. The highest quality cluster randomised trials suggested that spread of respiratory viruses can be prevented by hygienic measures in younger children and within households. Evidence that the more uncomfortable and expensive N95 masks were superior to simple surgical masks was limited, but they caused skin irritation. The incremental effect of adding virucidals or antiseptics to normal handwashing to reduce respiratory disease remains uncertain. Global measures, such as screening at entry ports, were not properly evaluated. Evidence was limited for social distancing being effective, especially if related to risk of exposure-that is, the higher the risk the longer the distancing period.Conclusion: Routine long term implementation of some of the measures to interrupt or reduce the spread of respiratory viruses might be difficult. However, many simple and low cost interventions reduce the transmission of epidemic respiratory viruses. More resources should be invested into studying which physical interventions are the most effective, flexible, and cost effective means of minimising the impact of acute respiratory tract infections."
AUTHORS
Ghada A Bawazeer
Lubna A Al-Ansary
Eliana Ferroni
Liz Dooley
Chris Del Mar
Tom Jefferson et al
PUBLISHED
2009 in BMJ : British Medical Journal
High quality source
Literature Review
Yes
Yes
16
Preliminary findings of a randomized trial of non-pharmaceutical interventions to prevent influenza transmission in households.
"Background: There are sparse data on whether non-pharmaceutical interventions can reduce the spread of influenza. We implemented a study of the feasibility and efficacy of face masks and hand hygiene to reduce influenza transmission among Hong Kong household members.Methodology/Principal Findings: We conducted a cluster randomized controlled trial of households (composed of at least 3 members) where an index subject presented with influenza-like-illness of <48 hours duration. After influenza was confirmed in an index case by the QuickVue Influenza A+B rapid test, the household of the index subject was randomized to 1) control or 2) surgical face masks or 3) hand hygiene. Households were visited within 36 hours, and 3, 6 and 9 days later. Nose and throat swabs were collected from index subjects and all household contacts at each home visit and tested by viral culture. The primary outcome measure was laboratory culture confirmed influenza in a household contact; the secondary outcome was clinically diagnosed influenza (by self-reported symptoms). We randomized 198 households and completed follow up home visits in 128; the index cases in 122 of those households had laboratory-confirmed influenza. There were 21 household contacts with laboratory confirmed influenza corresponding to a secondary attack ratio of 6%. Clinical secondary attack ratios varied from 5% to 18% depending on case definitions. The laboratory-based or clinical secondary attack ratios did not significantly differ across the intervention arms. Adherence to interventions was variable.Conclusions/Significance: The secondary attack ratios were lower than anticipated, and lower than reported in other countries, perhaps due to differing patterns of susceptibility, lack of significant antigenic drift in circulating influenza virus strains recently, and/or issues related to the symptomatic recruitment design. Lessons learnt from this pilot have informed changes for the main study in 2008.Trial Registration: ClinicalTrials.gov NCT00425893 HKClinicalTrials.com HKCTR-365."
AUTHORS
Raymond Yung
Wing Hong Seto
Kwok Hung Chan
J S Malik Peiris
Gabriel M Leung
Rita O P Fung et al
PUBLISHED
2008 in PLoS ONE
High quality source
Couldn't Identify
Couldn't Identify
17
Rapid awareness and transmission of severe acute respiratory syndrome in Hanoi French Hospital, Vietnam.
"A case-control study was conducted to examine the relationship between severe acute respiratory syndrome (SARS) and the time-dependent precautionary behaviors taken during an outbreak of SARS in Hanoi French Hospital (HFH), Vietnam. Masks (odds ratio [OR] = 0.3; 95% confidence interval [CI]: 0.1, 0.7) and gowns (OR = 0.2; 95% CI: 0.0, 0.8) appeared to prevent SARS transmission. The proportion of doctors and nurses who undertook each measure significantly improved (chi(2) = 9.8551, P = 0.043) after the onset of secondary cases. The impact of individual behaviors on an outbreak was investigated through mathematical approaches. The reproduction number decreased from 4.1 to 0.7 after notification. The basic reproduction number was estimated, and the use of masks alone was shown to be insufficient in containing an epidemic. Intuitive results obtained by means of stochastic individual-based simulations showed that rapid improvements in behavior and isolation would increase the probability of extinction."
AUTHORS
L E Dang Ha
Vo Van Ban
Nguyen Chi Phi
Tran Quy
Tadatoshi Kuratsuji
Hiroshi Nishiura et al
PUBLISHED
2005 in The American Journal of Tropical Medicine and Hygiene
High quality source
Yes
Yes
18
[Effectiveness of personal protective measures in prevention of nosocomial transmission of severe acute respiratory syndrome].
"Objective: To evaluate the effectiveness of personal protective measures of health care workers (HCWs) against severe acute respiratory syndrome (SARS).Methods: A case-control study from ten hospitals in Guangdong, with 180 non-infected and 77 infected staff members that accessed the isolation unit every day, and participated in direct first aid for severe SARS patients. All participants were surveyed about how they were using personal protective equipment (PPE), protective drugs and hygiene habits when caring for patients with SARS. Statistical analysis was done with either chi(2) or Fisher's exact test for univariate analysis, whereas we used forward stepwise selection (Waldesian) for logistic regression.Results: Univariate analysis showed that mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting", gargle, "membrane protection", "taking shower and changing clothing after work", "avoid from eating and drinking in ward", oseltamivir phospha tall had protective effects (P < 0.05), but stepwise logistic regression showed significant differences for mask (OR = 0.78, 95% CI: 0.60 - 0.99), goggles (OR = 0.20, 95% CI: 0.10 - 0.41) and footwear (OR = 0.58, 95% CI: 0.39 - 0.86). Analysis for linear trend in proportions showed that dose response relationship existed in mask, gown, gloves, goggles, footwear, gargle, "membrane protection" and "taking shower and changing dree after work" (P < 0.01). The attack rate of HCWs who were rescuing severe SARS patients without any PPE was 61.5% (16/26). It seemed that the more the protective measures were used, the higher the protective effect was (P < 0.001), and could reach 100% if mask, gown, gloves, goggles, footwear, "hand-washing and disinfecting" were all used at the same time.Conclusions: Nosocomial infection of SARS can be prevented effectively by precautions against droplets and personal contact. HCWs must take strict protection according to the guidance of WHO or Chinese MOH and pay attention to personal hygiene."
AUTHORS
Qin Zou
Xian-chang Zhang
Lin Du
Wei-sheng Lin
Li-dong Gao
Wen-wu Yin et al
PUBLISHED
Yes
Yes
19
Factors associated with transmission of severe acute respiratory syndrome among health-care workers in Singapore.
"Between 1 and 22 March 2003, a nosocomial outbreak of Severe Acute Respiratory Syndrome (SARS) occurred at the Communicable Disease Centre in Tan Tock Seng Hospital, Singapore, the national treatment and isolation facility for patients with SARS. A case-control study with 36 cases and 50 controls was conducted of factors associated with the transmission of SARS within the hospital. In univariate analysis, contact with respiratory secretions elevated the odds ratio to 6.9 (95 % CI 1.4-34.6, P= 0.02). Protection was conferred by hand washing (OR 0.06, 95% CI 0.007-0.5, P=0.03) and wearing of N95 masks (OR 0.1, 95% CI 0.03-0.4, P=0.001). Use of gloves and gowns had no effect. Multivariate analysis confirmed the strong role of contact with respiratory secretions (adjusted OR 21.8, 95 % CI 1.7 274.8, P=0.017). Both hand washing (adjusted OR 0.07, 95 % CI 0.008-0.66, P=0.02) and wearing of N95 masks (adjusted OR 0.1, 95% CI 0.02-0.86, P=0.04) remained strongly protective but gowns and gloves had no effect."
AUTHORS
B H Heng
Y S Leo
M D Teleman
D Zhu
I C Boudville
PUBLISHED
2004 in Epidemiology and Infection
Q2
Yes
Yes
20
SARS transmission, risk factors, and prevention in Hong Kong.
"We analyzed information obtained from 1,192 patients with probable severe acute respiratory syndrome (SARS) reported in Hong Kong. Among them, 26.6% were hospital workers, 16.1% were members of the same household as SARS patients and had probable secondary infections, 14.3% were Amoy Gardens residents, 4.9% were inpatients, and 9.9% were contacts of SARS patients who were not family members. The remaining 347 case-patients (29.1%) had undefined sources of infection. Excluding those <16 years of age, 330 patients with cases from "undefined" sources were used in a 1:2 matched case-control study. Multivariate analysis of this case-control study showed that having visited mainland China, hospitals, or the Amoy Gardens were risk factors (odds ratio [OR] 1.95 to 7.63). In addition, frequent mask use in public venues, frequent hand washing, and disinfecting the living quarters were significant protective factors (OR 0.36 to 0.58). In Hong Kong, therefore, community-acquired infection did not make up most transmissions, and public health measures have contributed substantially to the control of the SARS epidemic."
AUTHORS
Joseph T F Lau
Hiyi Tsui
Mason Lau
Xilin Yang
PUBLISHED
2004 in Emerging Infectious Diseases
High quality source
Yes
Yes







ADDITIONAL STUDIES TO CONSIDER ADDING TO LIST
Total additional studies: 55
State of K's algorithms generated the list of studies below based on the studies that were added to the above list. Some of these studies may also examine: "Does a surgical (non-N95) mask reduce the risk of contracting viruses that cause respiratory disease?" If a study examines this question, add it to the list by pressing the button.

Only add studies that examine the same question. Do not add studies that are merely on the same topic.

Respiratory Performance Offered by N95 Respirators and Surgical Masks: Human Subject Evaluation with NaCl Aerosol Representing Bacterial and Viral Particle Size Range
"Objectives: This study aimed at determining the protection factors (PFs) provided by N95 filtering facepiece respirators and surgical masks against particles representing bacterial and viral size ranges (aerodynamic size: 0.04-1.3 mum).

Methods: The protection levels of N95 filtering facepiece respirators (four models) and surgical masks (three models) were investigated while they were donned by 12 subjects performing the OSHA (US Occupational Safety and Health Administration) fit-testing exercises in a test chamber.

Results: About 29% of N95 respirators and approximately 100% of surgical masks had PFs <10, which is the assigned PF designated for this type of respirator by the OSHA. On average, the PFs of N95 respirators were 8-12 times greater than those of surgical masks. The minimum PFs were observed in the size range of 0.04-0.2 mum. No significant difference in PF results was found between N95 respirators with and without an exhalation valve.

Conclusions: The study indicates that N95 filtering facepiece respirators may not achieve the expected protection level against bacteria and viruses. An exhalation valve on the N95 respirator does not affect the respiratory protection; it appears to be an appropriate alternative to reduce the breathing resistance.

"
PUBLISHED
2008 in The Annals of Occupational Hygiene

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SARS among critical care nurses, Toronto.
"To determine factors that predispose or protect healthcare workers from severe acute respiratory syndrome (SARS), we conducted a retrospective cohort study among 43 nurses who worked in two Toronto critical care units with SARS patients. Eight of 32 nurses who entered a SARS patient's room were infected. The probability of SARS infection was 6% per shift worked. Assisting during intubation, suctioning before intubation, and manipulating the oxygen mask were high-risk activities. Consistently wearing a mask (either surgical or particulate respirator type N95) while caring for a SARS patient was protective for the nurses, and consistent use of the N95 mask was more protective than not wearing a mask. Risk was reduced by consistent use of a surgical mask, but not significantly. Risk was lower with consistent use of a N95 mask than with consistent use of a surgical mask. We conclude that activities related to intubation increase SARS risk and use of a mask (particularly a N95 mask) is protective."
AUTHORS
David Rose
Stephen D Walter
Karen Green
Marianna Ofner
Lorraine Moss
Stephanie Smith et al
PUBLISHED
2004 in Emerging Infectious Diseases

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Do N95 respirators provide 95% protection level against airborne viruses, and how adequate are surgical masks?
"Background: Respiratory protection devices are used to protect the wearers from inhaling particles suspended in the air. Filtering face piece respirators are usually tested utilizing nonbiologic particles, whereas their use often aims at reducing exposure to biologic aerosols, including infectious agents such as viruses and bacteria.

Methods: The performance of 2 types of N95 half-mask, filtering face piece respirators and 2 types of surgical masks were determined. The collection efficiency of these respiratory protection devices was investigated using MS2 virus (a nonharmful simulant of several pathogens). The virions were detected in the particle size range of 10 to 80 nm.

Results: The results indicate that the penetration of virions through the National Institute for Occupational Safety and Health (NIOSH)-certified N95 respirators can exceed an expected level of 5%. As anticipated, the tested surgical masks showed a much higher particle penetration because they are known to be less efficient than the N95 respirators. The 2 surgical masks, which originated from the same manufacturer, showed tremendously different penetration levels of the MS2 virions: 20.5% and 84.5%, respectively, at an inhalation flow rate of 85 L/min.

Conclusion: The N95 filtering face piece respirators may not provide the expected protection level against small virions. Some surgical masks may let a significant fraction of airborne viruses penetrate through their filters, providing very low protection against aerosolized infectious agents in the size range of 10 to 80 nm. It should be noted that the surgical masks are primarily designed to protect the environment from the wearer, whereas the respirators are supposed to protect the wearer from the environment.

"
AUTHORS
Satheesh K. Sivasubramani
Atin Adhikari
Sergey A. Grinshpun
Tiina Reponen
Mika Toivola
Anna Bałazy
PUBLISHED
2006 in American Journal of Infection Control

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Surgical mask versus N95 respirator for preventing influenza among health care workers: a randomized trial.
"CONTEXT:
Data about the effectiveness of the surgical mask compared with the N95 respirator for protecting health care workers against influenza are sparse. Given the likelihood that N95 respirators will be in short supply during a pandemic and not available in many countries, knowing the effectiveness of the surgical mask is of public health importance.

OBJECTIVE:
To compare the surgical mask with the N95 respirator in protecting health care workers against influenza.

DESIGN, SETTING, AND PARTICIPANTS:
Noninferiority randomized controlled trial of 446 nurses in emergency departments, medical units, and pediatric units in 8 tertiary care Ontario hospitals.

INTERVENTION:
Assignment to either a fit-tested N95 respirator or a surgical mask when providing care to patients with febrile respiratory illness during the 2008-2009 influenza season.

MAIN OUTCOME MEASURES:
The primary outcome was laboratory-confirmed influenza measured by polymerase chain reaction or a 4-fold rise in hemagglutinin titers. Effectiveness of the surgical mask was assessed as noninferiority of the surgical mask compared with the N95 respirator. The criterion for noninferiority was met if the lower limit of the 95% confidence interval (CI) for the reduction in incidence (N95 respirator minus surgical group) was greater than -9%.

RESULTS:
Between September 23, 2008, and December 8, 2008, 478 nurses were assessed for eligibility and 446 nurses were enrolled and randomly assigned the intervention; 225 were allocated to receive surgical masks and 221 to N95 respirators. Influenza infection occurred in 50 nurses (23.6%) in the surgical mask group and in 48 (22.9%) in the N95 respirator group (absolute risk difference, -0.73%; 95% CI, -8.8% to 7.3%; P = .86), the lower confidence limit being inside the noninferiority limit of -9%.

CONCLUSION:
Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza."
AUTHORS
Damon Atrie
Andrew Worster
PUBLISHED
2012 in CJEM

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Literature review
Protecting healthcare workers from pandemic influenza: N95 or surgical masks?
"Objective: The successful management of an influenza pandemic will be reliant on the expertise of healthcare workers at high risk for occupationally acquired influenza. Recommended infection control measures for healthcare workers include surgical masks to protect against droplet-spread respiratory transmissible infections and N95 masks to protect against aerosol-spread infections. A literature review was undertaken for evidence of superior protective value of N95 masks or surgical masks for healthcare workers against influenza and extraneous factors influencing conferred protection.

Methods: Four scientific search engines using 12 search sequences identified 21 mask studies in healthcare settings for the prevention of transmission of respiratory syncytial virus, Bordetella pertussis, and severe acute respiratory syndrome. Each was critically assessed in accordance with Australian National Health Medical Research Council guidelines. An additional 25 laboratory-based publications were also reviewed.

Results: All studies reviewed used medium or lower level evidence study design. In the majority of studies, important confounders included the unrecognized impact of concurrent bundling of other infection control measures, mask compliance, contamination from improper doffing of masks, and ocular inoculation. Only three studies directly compared the protective value of surgical masks with N95 masks. The majority of laboratory studies identified both mask types as having a range of filtration efficiency, yet N95 masks afford superior protection against particles of a similar size to influenza.

Conclusions: World Health Organization guidelines recommend surgical masks for all patient care with the exception of N95 masks for aerosol generating procedures. Because of the paucity of high-quality studies in the healthcare setting, the advocacy of mask types is not entirely evidence-based. Evidence from laboratory studies of potential airborne spread of influenza from shedding patients indicate that guidelines related to the current 1-meter respiratory zone may need to be extended to a larger respiratory zone and include protection from ocular inoculation.

"
AUTHORS
Jan Gralton
Mary-Louise McLaws
PUBLISHED
2010 in Critical Care Medicine

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Literature review
Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis.
"Background: Conflicting recommendations exist related to which facial protection should be used by health care workers to prevent transmission of acute respiratory infections, including pandemic influenza. We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections.

Methods: We searched various electronic databases and the grey literature for relevant studies published from January 1990 to December 2014. Randomized controlled trials (RCTs), cohort studies and case-control studies that included data on health care workers wearing N95 respirators and surgical masks to prevent acute respiratory infections were included in the meta-analysis. Surrogate exposure studies comparing N95 respirators and surgical masks using manikins or adult volunteers under simulated conditions were summarized separately. Outcomes from clinical studies were laboratory-confirmed respiratory infection, influenza-like illness and workplace absenteeism. Outcomes from surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage.

Results: We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case-control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64-1.24; cohort study: OR 0.43, 95% CI 0.03-6.41; case-control studies: OR 0.91, 95% CI 0.25-3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19-1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57-1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions, compared with surgical masks.

Interpretation: Although N95 respirators appeared to have a protective advantage over surgical masks in laboratory settings, our meta-analysis showed that there were insufficient data to determine definitively whether N95 respirators are superior to surgical masks in protecting health care workers against transmissible acute respiratory infections in clinical settings.

"
AUTHORS
Brian Schwartz
Jennie Johnstone
Gary E Garber
Ray A Copes
Colin C MacDougall
Jeffrey D Smith
PUBLISHED
2016 in CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne

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Literature review
Physical interventions to interrupt or reduce the spread of respiratory viruses. Part 1 - Face masks, eye protection and person distancing: systematic review and meta-analysis
"Abstract

OBJECTIVE: To examine the effectiveness of eye protection, face masks, or person distancing on
interrupting or reducing the spread of respiratory viruses.

DESIGN: Update of a Cochrane review that included a meta-analysis of observational studies during the SARS outbreak of 2003.

DATA SOURCES: Eligible trials from the previous review; search of Cochrane Central Register of
Controlled Trials, PubMed, Embase and CINAHL from October 2010 up to 1 April 2020; and forward
and backward citation analysis.

DATA SELECTION: Randomised and cluster-randomised trials of people of any age, testing the use of
eye protection, face masks, or person distancing against standard practice, or a similar physical
barrier. Outcomes included any acute respiratory illness and its related consequences.

DATA EXTRACTION AND ANALYSIS: Six authors independently assessed risk of bias using the Cochrane tool and extracted data. We used a generalised inverse variance method for pooling using a random-effects model and reported results with risk ratios and 95% Confidence Intervals (CI).

RESULTS: We included 15 randomised trials investigating the effect of masks (14 trials) in healthcare workers and the general population and of quarantine (1 trial). We found no trials testing eye protection. Compared to no masks there was no reduction of influenza-like illness (ILI) cases (Risk Ratio 0.93, 95%CI 0.83 to 1.05) or influenza (Risk Ratio 0.84, 95%CI 0.61-1.17) for masks in the general population, nor in healthcare workers (Risk Ratio 0.37, 95%CI 0.05 to 2.50). There was no difference between surgical masks and N95 respirators: for ILI (Risk Ratio 0.83, 95%CI 0.63 to 1.08), for influenza (Risk Ratio 1.02, 95%CI 0.73 to 1.43). Harms were poorly reported and limited to discomfort with lower compliance. The only trial testing quarantining workers with household ILI contacts found a reduction in ILI cases, but increased risk of quarantined workers contracting influenza. All trials were conducted during seasonal ILI activity.

CONCLUSIONS: Most included trials had poor design, reporting and sparse events. There was insufficient evidence to provide a recommendation on the use of facial barriers without other measures. We found insufficient evidence for a difference between surgical masks and N95 respirators and limited evidence to support effectiveness of quarantine. Based on observational evidence from the previous SARS epidemic included in the previous version of our Cochrane review we recommend the use of masks combined with other measures."
AUTHORS
Ghada Bawazeer
Lubna A Al Ansari
Elaine Beller
Tom Jefferson
Justin Clark
Mark Jones et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers
"Context: Data about the effectiveness of the surgical mask compared with the N95 respirator for protecting health care workers against influenza are sparse. Given the likelihood that N95 respirators will be in short supply during a pandemic and not available in many countries, knowing the effectiveness of the surgical mask is of public health importance.

Objective: To compare the surgical mask with the N95 respirator in protecting health care workers against influenza.

Design, Setting, And Participants: Noninferiority randomized controlled trial of 446 nurses in emergency departments, medical units, and pediatric units in 8 tertiary care Ontario hospitals.

Intervention: Assignment to either a fit-tested N95 respirator or a surgical mask when providing care to patients with febrile respiratory illness during the 2008-2009 influenza season.

Main Outcome Measures: The primary outcome was laboratory-confirmed influenza measured by polymerase chain reaction or a 4-fold rise in hemagglutinin titers. Effectiveness of the surgical mask was assessed as noninferiority of the surgical mask compared with the N95 respirator. The criterion for noninferiority was met if the lower limit of the 95% confidence interval (CI) for the reduction in incidence (N95 respirator minus surgical group) was greater than -9%.

Results: Between September 23, 2008, and December 8, 2008, 478 nurses were assessed for eligibility and 446 nurses were enrolled and randomly assigned the intervention; 225 were allocated to receive surgical masks and 221 to N95 respirators. Influenza infection occurred in 50 nurses (23.6%) in the surgical mask group and in 48 (22.9%) in the N95 respirator group (absolute risk difference, -0.73%; 95% CI, -8.8% to 7.3%; P = .86), the lower confidence limit being inside the noninferiority limit of -9%.

Conclusion: Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza.

Trial Registration: clinicaltrials.gov Identifier: NCT00756574

"
AUTHORS
Richard Webby
Stephen D. Walter
David J. D. Earn
Verne Glavin
Marek Smieja
Sylvia Chong et al
PUBLISHED
2009 in JAMA

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Surgical mask placement over N95 filtering facepiece respirators: Physiological effects on healthcare workers
"Background And Objective: Filtering facepiece respirators ('N95 Masks') may be in short supply during large-scale infectious outbreaks. Suggestions have been made to extend their useful life by using a surgical mask as an outer barrier, but the physiological impact of this added barrier upon the wearer has not been studied.

Methods: A surgical mask was worn over an N95 filtering facepiece respirator by 10 healthcare workers for 1 h at each of two work rates. Heart rate, respiratory rate, tidal volume, minute volume, oxygen saturation, transcutaneous carbon dioxide levels and respirator dead space gases were monitored and compared with controls (N95 filtering facepiece respirator without a surgical mask). Subjective perceptions of exertion and comfort were assessed by numerical rating scales.

Results: There were no significant differences in physiological variables between those who used surgical masks and controls. Surgical masks decreased dead space oxygen concentrations of the filtering facepiece respirators at the lesser work rate (P = 0.03) and for filtering facepiece respirators with an exhalation valve at the higher work rate (P = 0.003). Respirator dead space oxygen and carbon dioxide levels were not harmonious with Occupational Safety and Health Administration workplace ambient atmosphere standards. Exertion and comfort scores were not significantly impacted by the surgical mask.

Conclusions: Use of a surgical mask as an outer barrier over N95 filtering facepiece respirators does not significantly impact the physiological burden or perceptions of comfort and exertion by the wearer over that experienced without use of a surgical mask.

"
AUTHORS
Jeffrey B. POWELL
Andrew J. PALMIERO
W. Jon WILLIAMS
Aitor COCA
Raymond J. ROBERGE
PUBLISHED
2010 in Respirology

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Disposable N95 Masks Pass Qualitative Fit-Test But Have Decreased Filtration Efficiency after Cobalt-60 Gamma Irradiation
"The current COVID-19 pandemic has led to a dramatic shortage of masks and other personal protective equipment (PPE) in hospitals around the globe. One component of PPE that is in particular demand are disposable N95 face masks. To alleviate this, many methods of N95 mask sterilization have been studied and proposed with the hope of being able to safely reuse masks. Two major considerations must be made when re-sterilizing masks: (1) the sterilization method effectively kills pathogens, penetrating into the fibers of the mask, and (2) the method does not degrade the operational integrity of the N95 filters.

We studied Cobalt-60 gamma irradiation as a method of effective sterilization without inducing mask degradation. Significant literature exists supporting the use of gamma radiation as a sterilization method, with viral inactivation of SARS-CoV reported at doses of at most 10 kGy, with other studies supporting 5 kGy for many types of viruses. However, concerns have been raised about the radiation damaging the fiber material within the mask, specifically by causing cross-linking of polymers, leading to cracking and degradation during fitting and/or deployment.

A set of 3M 8210 and 9105 masks were irradiated using MIT's Co-60 irradiator. Three masks of each type received 0 kiloGray (kGy), 10 kGy and 50 kGy of approximately 1.3 MeV gamma radiation from the circular cobalt sources, at a dose rate of 2.2 kGy per hour.

Following this sterilization procedure, the irradiated masks passed a OSHA Gerson Qualitative Fit Test QLFT 50 (saccharin apparatus) when donned correctly, performed at the Brigham and Women's Hospital, in a blinded study repeated in triplicate. However, the masks' filtration of 0.3 um particles was significantly degraded, even at 10 kGy.

These results suggest against gamma, and possibly all ionizing radiation, as a method of disposable N95 sterilization. Even more importantly, they argue against using the qualitative fit test alone to assess mask integrity."
AUTHORS
Mitchell Galanek
Sherryl H Yu
Enze Tian
Avilash Cramer
Rajiv Gupta
Michael P Short et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Homemade cloth face masks to fight the COVID19 pandemic; a call for mass public masking with homemade cloth masks
"As we face the COVID-19 pandemic our country is largely ignoring a potential transmission control tool – the community’s use of facial masks in public spaces. Ample evidence from historical studies (early 1900’s), modern filtration experiments of different materials and pathogens, and observational studies exists to suggest that mass masking of the community would decrease the transmissivity of SARS-CoV-2 and accelerate the flattening of the curve in which we are engaged. The WHO and CDC claim a lack of randomized trials as rationale for not promoting community use of face masks. But we have shut down the schools, workplaces, and social events. Where are the randomized trials of social distancing? We trust the science on social distancing. Let us trust the science on the community use of face masks. Given the aggressive nature of the pathogen we face we should bring all potential interventions to the fight against COVID-19, including the mass use of face masks of the community. With potentially devastating shortages of N95 respirators and surgical masks for clinicians, community masks should be homemade cloth that are effective at acting as source control interventions. Let us scale up the fabrication of a billion homemade cloth face masks and wear them in public."
AUTHOR
David Larsen
PUBLISHED
2020 in Center for Open Science

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Noninvasive ventilation masks with viral filters to protect health care workers from SARS-CoV-2 / Coronavirus infections
"Abstract

Background:There is a shortage of masks and respirators for the protection of health care professionals during the current SARS-CoV-2 / Coronavirus pandemic. Masks for non-invasive ventilation (NIV) in combination with viral-proof filters could serve as an alternative protection measure. We wanted to determine the aerosol filtering efficacies of such devices in comparison to conventional surgical masks, N95 and FFP3 respirators.Method:Masks and respirators were mounted on a ventilated mannequin head in a test-chamber. Absorption of radioactive particles was measured compared to a non-filtered reference port.Results: Filter efficacies were 93.3 ± 1.5 % for a ResMed AcuCare NIV-mask plus filter, 71.2 ± 0.2 % for a ResMed Mirage Quattro FX NIV-mask plus filter, 89.4 ± 0.9 % for a Loewenstein JOYCEclinc FF NIV-mask plus filter, 48.4 ± 4 % for a surgical mask with rubber band, 60.5 ± 9.1 % for a surgical mask with ribbons, 56.9 ± 7.5 % for a FFP3 respirator, 64.5 % ± 5.1 for a N95 respirator. The ResMed AcuCare and the Loewenstein JOYCEclinic FF mask were more effective than any other of the tested devices (p &lt; 0.001 and p = 0.001 respectively)Conclusion:NIV masks with viral-proof filters effectively filter respirable particles. Two tested NIV masks were more effective than the tested FFP3 and N95 respirators.
"
AUTHORS
Peter Haidl
Jens Kerl
Dominic Dellweg
Dieter Koehler
PUBLISHED
2020 in Research Square

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The physiological impact of wearing an N95 mask during hemodialysis as a precaution against SARS in patients with end-stage renal disease.
"Background And Purpose: Most patients with end-stage renal disease (ERSD) visiting our hospital for hemodialysis treatment during the SARS outbreak wore an N95 mask. Data on the physiological stress imposed by the wearing of N95 masks remains limited. This study investigated the physiological impact of wearing an N95 mask during hemodialysis (HD) on patients with ESRD.

Methods: ESRD patients who received regular HD at National Taiwan University Hospital between April to June 2003 were enrolled. Each patient wore a new N95 mask (3M Model 8210) during HD (4 hours). Vital signs, clinical symptoms and arterial blood gas measured before and at the end of HD were compared.

Results: Thirty nine patients (23 men; mean age, 57.2 years) were recruited for participation in the study. Seventy percent of the patients showed a reduction in partial pressure of oxygen (PaO2), and 19% developed various degrees of hypoxemia. Wearing an N95 mask significantly reduced the PaO2 level (101.7 +/- 12.6 to 92.7 +/- 15.8 mm Hg, p = 0.006), increased the respiratory rate (16.8 +/- 2.8 to 18.8 +/- 2.7/min, p < 0.001), and increased the occurrence of chest discomfort (3 to 11 patients, p = 0.014) and respiratory distress (1 to 17 patients, p < 0.001). Baseline PaO2 level was the only significant predictor of the magnitude of PaO2 reduction (p < 0.001).

Conclusion: Wearing an N95 mask for 4 hours during HD significantly reduced PaO2 and increased respiratory adverse effects in ESRD patients.

"
AUTHORS
Tun-Jun Tsai
Tze-Wah Kao
Ming-Shiou Wu
Bor-Shen Hsieh
Kuo-Chiang Huang
Yu-Ling Huang
PUBLISHED
2004 in Journal of the Formosan Medical Association = Taiwan yi zhi

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Protecting healthcare staff from severe acute respiratory syndrome: filtration capacity of multiple surgical masks
"Guidelines issued by the Centers for Disease Control and Prevention and the World Health Organisation state that healthcare workers should wear N95 masks or higher-level protection during all contact with suspected severe acute respiratory syndrome (SARS). In areas where N95 masks are not available, multiple layers of surgical masks have been tried to prevent transmission of SARS. The in vivo filtration capacity of a single surgical mask is known to be poor. However, the filtration capacity of a combination of masks is unknown. This was a crossover trial of one, two, three and five surgical masks in six volunteers to determine the in vivo filtration efficiency of wearing more than one surgical mask. We used a Portacount to measure the difference in ambient particle counts inside and outside the masks. The best combination of five surgical masks scored a fit factor of 13.7, which is well below the minimum level of 100 required for a half face respirator. Multiple surgical masks filter ambient particles poorly. They should not be used as a substitute for N95 masks unless there is no alternative."
AUTHORS
C.D. Gomersall
J.L. Derrick
PUBLISHED
2005 in Journal of Hospital Infection

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Association between 2019-nCoV transmission and N95 respirator use
FUNDERS
Wuhan University
"A randomized clinical trial has reported that the N95 respirators vs medical masks resulted in no significant difference in the incidence of laboratory confirmed influenza4. In our study, we observed that the N95 respirators, disinfection and hand washing appear to help reduce the infectious risk of 2019-nCoV in doctors and nurses. Interestingly, departments with a high proportion of male doctors seemed to have a higher risk of infection. Our results emphasize the need for strict occupational protection measures in fighting COVID-19."
AUTHORS
Zhenyu Pan
Zhenshun Cheng
Xinghuan Wang
PUBLISHED
2020 in Journal of Hospital Infection

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Injection Molded Autoclavable, Scalable, Conformable (iMASC) system for aerosol-based protection
"There is a dire need for personal protective equipment (PPE) within healthcare settings during the COVID-19 pandemic. In particular, single use disposable N95 face masks have been limited in supply. We have developed an Injection Molded Autoclavable, Scalable, Conformable (iMASC) system for aerosol-based protection. The iMASC system was designed as a reusable liquid silicone rubber mask with disposable N95 filter cartridges that can fit most face sizes and shapes. This system reduced the amount of N95 filter while preserving breathability and fit. Using finite element analysis, we demonstrated mask deformation and reaction forces from facial scans of twenty different wearers. In addition, we validated these findings by succesful fit testing in twenty participants in a prospective clinical trial. The iMASC system has the potential to protect our healthcare workers with a reusable N95-comparable face mask that is rapidly scalable."
AUTHORS
Canchen Li
Sahab Babaee
Hen-Wei Huang
Adam Wentworth
James D Byrne
Carlo Traverso et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Physical interventions to interrupt or reduce the spread of respiratory viruses
You can view the abstract at: https://doi.org/10.1111/j.1744-1609.2012.00268.x
AUTHOR
Dawn Kozlowski
PUBLISHED
2012 in International Journal of Evidence-Based Healthcare

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Physical interventions to interrupt or reduce the spread of respiratory viruses
You can view the abstract at: https://doi.org/10.1002/14651858.cd006207.pub4
AUTHORS
Ghada A Bawazeer
Sreekumaran Nair
Mark A Jones
Liz Dooley
Chris B Del Mar
Tom Jefferson et al
PUBLISHED
2011 in Cochrane Database of Systematic Reviews

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Literature review
Physical interventions to interrupt or reduce the spread of respiratory viruses.
"Background: Viral epidemics or pandemics of acute respiratory infections like influenza or severe acute respiratory syndrome pose a world-wide threat. Antiviral drugs and vaccinations may be insufficient to prevent catastrophe.

Objectives: To systematically review the effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.

Search Strategy: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2); MEDLINE (1966 to May 2009); OLDMEDLINE (1950 to 1965); EMBASE (1990 to May 2009); and CINAHL (1982 to May 2009).

Selection Criteria: We scanned 2958 titles, excluded 2790 and retrieved the full papers of 168 trials, to include 59 papers of 60 studies. We included any physical interventions (isolation, quarantine, social distancing, barriers, personal protection and hygiene) to prevent transmission of respiratory viruses. We included the following study designs: randomised controlled trials (RCTs), cohorts, case controls, cross-over, before-after, and time series studies.

Data Collection And Analysis: We used a standardised form to assess trial eligibility. RCTs were assessed by: randomisation method; allocation generation; concealment; blinding; and follow up. Non-RCTs were assessed for the presence of potential confounders, and classified into low, medium, and high risks of bias.

Main Results: The risk of bias for the four RCTs, and most cluster RCTs, was high. The observational studies were of mixed quality. Only case-control data were sufficiently homogeneous to allow meta-analysis.The highest quality cluster RCTs suggest respiratory virus spread can be prevented by hygienic measures, such as handwashing, especially around younger children. Additional benefit from reduced transmission from children to other household members is broadly supported in results of other study designs, where the potential for confounding is greater. Six case-control studies suggested that implementing barriers to transmission, isolation, and hygienic measures are effective at containing respiratory virus epidemics. We found limited evidence that N95 respirators were superior to simple surgical masks, but were more expensive, uncomfortable, and caused skin irritation. The incremental effect of adding virucidals or antiseptics to normal handwashing to decrease respiratory disease remains uncertain. Global measures, such as screening at entry ports, were not properly evaluated. There was limited evidence that social distancing was effective especially if related to the risk of exposure.

Authors' Conclusions: Many simple and probably low-cost interventions would be useful for reducing the transmission of epidemic respiratory viruses. Routine long-term implementation of some of the measures assessed might be difficult without the threat of a looming epidemic."
AUTHORS
Ghada A Bawazeer
Lubna A Al-Ansary
Eliana Ferroni
Liz Dooley
Chris Del Mar
Tom Jefferson et al
PUBLISHED
2010 in Cochrane Database of Systematic Reviews

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Literature review
Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review.
"Objective: To systematically review evidence for the effectiveness of physical interventions to interrupt or reduce the spread of respiratory viruses.

Data Extraction: Search strategy of the Cochrane Library, Medline, OldMedline, Embase, and CINAHL, without language restriction, for any intervention to prevent transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection, and hygiene). Study designs were randomised trials, cohort studies, case-control studies, and controlled before and after studies.

Data Synthesis: Of 2300 titles scanned 138 full papers were retrieved, including 49 papers of 51 studies. Study quality was poor for the three randomised controlled trials and most of the cluster randomised controlled trials; the observational studies were of mixed quality. Heterogeneity precluded meta-analysis of most data except that from six case-control studies. The highest quality cluster randomised trials suggest that the spread of respiratory viruses into the community can be prevented by intervening with hygienic measures aimed at younger children. Meta-analysis of six case-control studies suggests that physical measures are highly effective in preventing the spread of SARS: handwashing more than 10 times daily (odds ratio 0.45, 95% confidence interval 0.36 to 0.57; number needed to treat=4, 95% confidence interval 3.65 to 5.52); wearing masks (0.32, 0.25 to 0.40; NNT=6, 4.54 to 8.03); wearing N95 masks (0.09, 0.03 to 0.30; NNT=3, 2.37 to 4.06); wearing gloves (0.43, 0.29 to 0.65; NNT=5, 4.15 to 15.41); wearing gowns (0.23, 0.14 to 0.37; NNT=5, 3.37 to 7.12); and handwashing, masks, gloves, and gowns combined (0.09, 0.02 to 0.35; NNT=3, 2.66 to 4.97). The incremental effect of adding virucidals or antiseptics to normal handwashing to decrease the spread of respiratory disease remains uncertain. The lack of proper evaluation of global measures such as screening at entry ports and social distancing prevent firm conclusions being drawn.

Conclusion: Routine long term implementation of some physical measures to interrupt or reduce the spread of respiratory viruses might be difficult but many simple and low cost interventions could be useful in reducing the spread.

"
AUTHORS
Bill Hewak
Eliana Ferroni
Liz Dooley
Chris Del Mar
Ruth Foxlee
Tom Jefferson et al
PUBLISHED

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Literature review
Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review
You can view the abstract at: https://doi.org/10.1136/bmj.39393.510347.be
AUTHORS
A. Prabhala
B. Hewak
A. Rivetti
E. Ferroni
L. Dooley
T. Jefferson et al
PUBLISHED
2008 in BMJ

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Literature review
Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review
You can view the abstract at: https://doi.org/10.1136/bmj.b3675
AUTHORS
L. A Al-Ansary
A. Rivetti
C. Del Mar
E. Ferroni
L. Dooley
T. Jefferson et al
PUBLISHED
2009 in BMJ

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Interventions for the interruption or reduction of the spread of respiratory viruses
You can view the abstract at: https://doi.org/10.3310/hta1434-06
PUBLISHED
2010 in Cochrane Database of Systematic Reviews

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Literature review
Highly regarded source
Interventions for the interruption or reduction of the spread of respiratory viruses.
"Background: Viral epidemics or pandemics such as of influenza or severe acute respiratory syndrome (SARS) pose a significant threat. Antiviral drugs and vaccination may not be adequate to prevent catastrophe in such an event.

Objectives: To systematically review the evidence of effectiveness of interventions to interrupt or reduce the spread of respiratory viruses (excluding vaccines and antiviral drugs, which have been previously reviewed).

Search Strategy: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 4); MEDLINE (1966 to November 2006); OLDMEDLINE (1950 to 1965); EMBASE (1990 to November 2006); and CINAHL (1982 to November 2006).

Selection Criteria: We scanned 2300 titles, excluded 2162 and retrieved the full papers of 138 trials, including 49 papers of 51 studies. The quality of three randomised controlled trials (RCTs) was poor; as were most cluster RCTs. The observational studies were of mixed quality. We were only able to meta-analyse case-control data. We searched for any interventions to prevent viral transmission of respiratory viruses (isolation, quarantine, social distancing, barriers, personal protection and hygiene). Study design included RCTs, cohort studies, case-control studies, cross-over studies, before-after, and time series studies.

Data Collection And Analysis: We scanned the titles, abstracts and full text articles using a standardised form to assess eligibility. RCTs were assessed according to randomisation method, allocation generation, concealment, blinding, and follow up. Non-RCTs were assessed for the presence of potential confounders and classified as low, medium, and high risk of bias.

Main Results: The highest quality cluster RCTs suggest respiratory virus spread can be prevented by hygienic measures around younger children. Additional benefit from reduced transmission from children to other household members is broadly supported in results of other study designs, where the potential for confounding is greater. The six case-control studies suggested that implementing barriers to transmission, isolation, and hygienic measures are effective at containing respiratory virus epidemics. We found limited evidence that the more uncomfortable and expensive N95 masks were superior to simple surgical masks. The incremental effect of adding virucidals or antiseptics to normal handwashing to decrease respiratory disease remains uncertain. The lack of proper evaluation of global measures such as screening at entry ports and social distancing prevent firm conclusions about these measures.

Authors' Conclusions: Many simple and probably low-cost interventions would be useful for reducing the transmission of epidemic respiratory viruses. Routine long-term implementation of some of the measures assessed might be difficult without the threat of a looming epidemic.

"
AUTHORS
R Foxlee
L Dooley
T Jefferson
A Prabhala
E Ferroni
B Hewak et al
PUBLISHED
2007 in The Cochrane Database of Systematic Reviews

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Dispersal of respiratory droplets with open vs closed oxygen delivery masks: implications for the transmission of severe acute respiratory syndrome.
"Nosocomial transmission of droplet-borne respiratory infections such as severe acute respiratory syndrome (SARS) may be influenced by the choice of oxygen face mask. A subject inhaled saline mist and exhaled through three oxygen masks to illustrate the pattern of dispersal of pulmonary gas. In two commonly used masks, exhaled gas formed a plume emanating from the side vents, while a third mask with a valved manifold, which was modified by adding a respiratory filter, retained the droplets. Maintaining respiratory isolation during the administration of oxygen may reduce the risk of the nosocomial transmission of respiratory infections such as SARS."
AUTHORS
Joe Correia
Joseph Fisher
David Preiss
Takafumi Azami
Alex E Vesely
Ron Somogyi et al
PUBLISHED

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Risk factors for SARS infection within hospitals in Hanoi, Vietnam.
"We investigated a nosocomial infection of severe acute respiratory syndrome (SARS) in Vietnam in 2003 and attempted to identify risk factors for SARS infection. Of the 146 subjects who came into contact with SARS patients at Hospital A, 43 (29.5%) developed SARS, and an additional 16 (11%) were asymptomatic but SARS-coronavirus (CoV) seropositive. The asymptomatic infection rate accounted for 15.5% of the total number of infected patients at Hospital A, which was higher than that of 6.5% observed at Hospital B, to where all patients from Hospital A were eventually transported (P<0.05). At Hospital A, the risk for developing SARS was 12.6 times higher in individuals not using a mask than in those using a mask. The SARS epidemic in Vietnam resulted in numerous secondary infections due to its unknown etiology and delayed recognition at the beginning of the epidemic. The consistent and proper use of a mask was shown to be crucial for constant protection against infection with SARS."
AUTHORS
Naoto Keicho
Hoang Thuy Long
Vo Van Ban
Naomi Wakasugi
Tran Quy
Ayako Nishiyama et al
PUBLISHED
2008 in Japanese Journal of Infectious Diseases

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Atypical SARS and Escherichia coli bacteremia.
"We describe a patient with severe acute respiratory syndrome (SARS) whose clinical symptoms were masked by Escherichia coli bacteremia. SARS developed in a cluster of healthcare workers who had contact with this patient. SARS was diagnosed when a chest infiltrate developed and when the patient's brother was hospitalized with acute respiratory failure. We highlight problems in atypical cases and offer infection control suggestions."
AUTHORS
Ai Ee Ling
Xin Lai Bai
Su Yun Se Thoe
Asok Kurup
Derrick Heng
Lynette Lin Ean Oon et al
PUBLISHED
2004 in Emerging Infectious Diseases

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Asymptomatic SARS coronavirus infection among healthcare workers, Singapore.
"We conducted a study among healthcare workers (HCWs) exposed to patients with severe acute respiratory syndrome (SARS) before infection control measures were instituted. Of all exposed HCWs, 7.5% had asymptomatic SARS-positive cases. Asymptomatic SARS was associated with lower SARS antibody titers and higher use of masks when compared to pneumonic SARS."
AUTHORS
Annelies Wilder-Smith
Ai E Ling
Arul Earnest
Yee S Leo
Bee H Heng
Monica D Teleman
PUBLISHED
2005 in Emerging Infectious Diseases

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SARS preventive and risk behaviours of Hong Kong air travellers.
"This study aims to investigate Severe Acute Respiratory Syndrome (SARS)-related behaviours of travellers returning to Hong Kong by air. A total of 820 travellers returning to Hong Kong by air were interviewed about their SARS-related behaviours in April 2003. Three quarters of the respondents wore a mask most/all of the time on board, 15% did so in public places at the travel destination. Perceived susceptibility to SARS at the destination predicted mask-wearing in public places and avoidance of crowded places, and perceived efficacy was a predictor for mask-wearing during flight. Approximately 16% of the respondents stated that they would delay their medical consultation for flu-like symptoms until returning to Hong Kong. Nearly 18.2% stated that they would not wear a mask in public places at the destination if they had flu-like symptoms. Education programmes, special services and effective thermal screening are required to minimize the chance of the spread of SARS by air travellers."
AUTHORS
Jean H Kim
Ellie Pang
Hiyi Tsui
Xilin Yang
Joseph T F Lau
PUBLISHED

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Widespread use of face masks in public may slow the spread of SARS CoV-2: an ecological study
"Background
The reasons for the large differences between countries in the sizes of their SARS CoV2 epidemics is unknown. Individual level studies have found that the use of face masks was protective for the acquisition and transmission of a range of respiratory viruses including SARS CoV1. We hypothesized that population level usage of face masks may be negatively associated SARS CoV2 spread.

Methods
At a country level, linear regression was used to assess the association between COVID19 diagnoses per inhabitant and the national promotion of face masks in public (coded as a binary variable), controlling for the age of the COVID19 epidemic and testing intensity.

Results
Eight of the 49 countries with available data advocated wearing face masks in public: China, Czechia, Hong Kong, Japan, Singapore, South Korea, Thailand and Malaysia. In multivariate analysis face mask use was negatively associated with number of COVID19 cases/inhabitant (coef. -326, 95% CI -601- -51, P=0.021). Testing intensity was positively associated with COVID-19 cases (coef. 0.07, 95% CI 0.05-0.08, P&lt;0.001).

Conclusion
Whilst these results are susceptible to residual confounding, they do provide ecological level support to the individual level studies that found face mask usage to reduce the transmission and acquisition of respiratory viral infections."
AUTHOR
Chris Kenyon
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Angiotensin-converting enzyme 2 (ACE2) from raccoon dog can serve as an efficient receptor for the spike protein of severe acute respiratory syndrome coronavirus
"Raccoon dog is one of the suspected intermediate hosts of severe acute respiratory syndrome coronavirus (SARS-CoV). In this study, the angiotensin-converting enzyme 2 (ACE2) gene of raccoon dog (rdACE2) was cloned and sequenced. The amino acid sequence of rdACE2 has identities of 99.3, 89.2, 83.9 and 80.4 % to ACE2 proteins from dog, masked palm civet (pcACE2), human (huACE2) and bat, respectively. There are six amino acid changes in rdACE2 compared with huACE2, and four changes compared with pcACE2, within the 18 residues of ACE2 known to make direct contact with the SARS-CoV S protein. A HeLa cell line stably expressing rdACE2 was established; Western blot analyses and an enzyme-activity assay indicated that the cell line expressed ACE2 at a similar level to two previously established cell lines that express ACE2 from human and masked palm civet, respectively. Human immunodeficiency virus-backboned pseudoviruses expressing spike proteins derived from human SARS-CoV or SARS-CoV-like viruses of masked palm civets and raccoon dogs were tested for their entry efficiency into these cell lines. The results showed that rdACE2 is a more efficient receptor for human SARS-CoV, but not for SARS-CoV-like viruses of masked palm civets and raccoon dogs, than huACE2 or pcACE2. This study provides useful data to elucidate the role of raccoon dog in SARS outbreaks."
AUTHORS
H. Deng
Y. Zhang
L. Xu
Z. Chen
Z. Ma
Y. Liu et al
PUBLISHED
2009 in Journal of General Virology

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Wearing masks in a pediatric hospital: developing practical guidelines.
"During the outbreak of Severe Acute Respiratory Syndrome (SARS) in the spring of 2003, strict infection control measures were implemented in Toronto and surrounding hospitals. These measures included extreme restrictions on those who would normally accompany patients to the hospital, screening for SARS, and protective attire for hospital staff, including masks, face shields, goggles, gloves and gowns. At Toronto's Hospital for Sick Children (HSC), patients could only be accompanied or visited by one person, often only in patients' rooms. For the first four weeks, patients and their designated parent had to wear masks in almost all areas of the hospital. Staff wore masks (and other appropriate protective clothing) whenever in contact with patients and in many patient care areas. Although these barriers were an important part of containing SARS, their use created significant challenges for patients and staff. This article focusses on the use of infection control masks in routine pediatric healthcare and the tools developed by HSC staff to reduce the negative psychosocial impact on children and families."
AUTHORS
Deborah Berlin
Kimberley Meighan
Wendy Shama
Barbara J Neilson
Marcia Beck
Miriam Kaufman et al
PUBLISHED
2004 in Canadian journal of public health = Revue canadienne de sante publique

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Detection of airborne respiratory syncytial virus in a pediatric acute care clinic
FUNDERS
National Institutes of Health
"Objective: Respiratory syncytial virus (RSV) is the most common cause of respiratory illness in infants and young children, but this virus is also capable of re-infecting adults throughout life. Universal precautions to prevent its transmission consist of gown and glove use, but masks and goggles are not routinely required because it is believed that RSV is unlikely to be transmitted by the airborne route. Our hypothesis was that RSV is present in respirable-size particles aerosolized by patients seen in a pediatric acute care setting.

Study Design: RSV-laden particles were captured using stationary 2-stage bioaerosol cyclone samplers. Aerosol particles were separated into three size fractions (<1, 1-4.1, and ≥4.1 μm) and were tested for the presence of RSV RNA by real-time PCR. Samplers were set 152 cm ("upper") and 102 cm ("lower") above the floor in each of two examination rooms.

Results: Of the total, 554 samples collected over 48 days, only 13 (or 2.3%) were positive for RSV. More than 90% of the RSV-laden aerosol particles were in the ≥4.1 μm size range, which typically settle to the ground within minutes, whereas only one sample (or 8%) was positive for particles in the 1-4.1 μm respirable size range.

Conclusions: Our data indicate that airborne RSV-laden particles can be detected in pediatric outpatient clinics during the epidemic peak. However, RSV airborne transmission is highly inefficient. Thus, the logistical and financial implications of mandating the use of masks and goggles to prevent RSV spread seem unwarranted in this setting. Pediatr Pulmonol. 2017;52:684-688. © 2016 Wiley Periodicals, Inc.

"
AUTHORS
Miriam K. Perez
Stephanie A. Grayson
Giovanni Piedimonte
Pamela S. Griffiths
PUBLISHED
2016 in Pediatric Pulmonology

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[Effects of selenium supplement on acute lower respiratory tract infection caused by respiratory syncytial virus].
"An intervention study was conducted in 75 young children under one year hospitalized with pneumonia or bronchiolitis caused by respiratory syncytial virus (RSV) to evaluate therapeutic effectiveness of selenium (Se) supplement on acute respiratory lower tract infection caused by RSV with randomly controlled and double-masked method. Trial subjects were divided into two groups, one with 37 children in routine treatment and the other with 38 children in routine treatment plus Se supplement. The control group derived from 35 normal children during their physical check-up in the out-patient department. Sodium selenite was supplemented orally with 1 mg on the second day of hospitalization. Results showed that days needed for their relief of symptoms and signs were fewer in Se supplement group than that in controls and recovery in indicators of cell immune was better in the former than that in the latter. Levels of Se and glutathione peroxidase in plasma and white cells could be increased by Se supplement. It suggests that Se supplement can promote recovery from RSV infection."
AUTHORS
S Yin
G Li
X Liu
PUBLISHED
1997 in Zhonghua yu fang yi xue za zhi [Chinese journal of preventive medicine]

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Literature review
Best practice in the prevention and management of paediatric respiratory syncytial virus infection.
"Respiratory syncytial virus (RSV) infection is ubiquitous with almost all infants having been infected by 2 years of age and lifelong repeated infections common. It is the second largest cause of mortality, after malaria, in infants outside the neonatal period and causes up to 200,000 deaths per year worldwide. RSV results in clinical syndromes that include upper respiratory tract infections, otitis media, bronchiolitis (up to 80% of cases) and lower respiratory tract disease including pneumonia and exacerbations of asthma or viral-induced wheeze. For the purposes of this review we will focus on RSV bronchiolitis in infants in whom the greatest disease burden lies. For infants requiring hospital admission, the identification of the causative respiratory virus is used to direct cohorting or isolation and infection control procedures to minimize nosocomial transmission. Nosocomial RSV infections are associated with poorer clinical outcomes, including increased mortality, the need for mechanical ventilation and longer length of hospital stay. Numerous clinical guidelines for the management of infants with bronchiolitis have been published, although none are specific for RSV bronchiolitis. Ribavirin is the only licensed drug for the specific treatment of RSV infection but due to drug toxicity and minimal clinical benefit it has not been recommended for routine clinical use. There is currently no licensed vaccine to prevent RSV infection but passive immunoprophylaxis using a monoclonal antibody, palivizumab, reduces the risk of hospitalization due to RSV infection by 39-78% in various high-risk infants predisposed to developing severe RSV disease. The current management of RSV bronchiolitis is purely supportive, with feeding support and oxygen supplementation until the infant immune system mounts a response capable of controlling the disease. The development of a successful treatment or prophylactic agent has the potential to revolutionize the care and outcome for severe RSV infections in the world's most vulnerable infants. "
AUTHORS
Christopher A Green
Charles J Sande
Simon B Drysdale
PUBLISHED
2016 in Therapeutic advances in infectious disease

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Transmission of respiratory syncytial virus at the paediatric intensive-care unit: a prospective study using real-time PCR
"Transmission of respiratory syncytial virus (RSV) from children with lower respiratory tract infection (LRTI) at a paediatric intensive-care unit (PICU) was examined using a highly sensitive real-time PCR. Twenty-four children with RSV LRTI were admitted during the study period (total days of potential transmission: 239). Forty-eight RSV-negative patients were followed up for RSV acquisition every 5 days (total days of exposure: 683). No single RSV transmission was documented with this highly sensitive diagnostic method. Therefore, routine infection control measures of LRTI patients seem to be adequate to prevent RSV transmission at the PICU."
AUTHORS
A.M. van Loon
J.L.L. Kimpen
E.K. Breteler
T.F.W. Wolfs
J.W.A. Rossen
A.C. van de Pol et al
PUBLISHED

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Risk factors in children hospitalized with RSV bronchiolitis versus non-RSV bronchiolitis.
"Background: The trends in hospitalization rates and risk factors for severe bronchiolitis have not been recently described, especially after the routine implementation of prophylaxis for respiratory syncytial virus (RSV) infections.

Objectives: To define the burden of hospitalizations related to RSV and non-RSV bronchiolitis in a tertiary-care children's hospital from 2002 to 2007 and to identify the risk factors associated with severe disease.

Methods: Medical records of patients hospitalized for bronchiolitis were reviewed for demographic, clinical, microbiologic, and radiologic characteristics as well as the presence of underlying medical conditions. Differences were evaluated between children with RSV and non-RSV bronchiolitis, and multivariable logistic regression analyses were performed to identify independent risk factors for severe disease.

Results: Bronchiolitis hospitalizations in children younger than 2 years old (n = 4800) significantly increased from 536 (3.3%) in 2002 to 1241 (5.5%) in 2007, mainly because of RSV infections. Patients with RSV bronchiolitis (n = 2840 [66%]) were younger at hospitalization and had a lower percentage of underlying medical conditions than children hospitalized with non-RSV bronchiolitis (27 vs 37.5%; P < .001). However, disease severity defined by length of hospitalization and requirement of supplemental oxygen, intensive care, and mechanical ventilation was significantly worse in children with RSV bronchiolitis. RSV infection and prematurity, regardless of the etiology, were identified as independent risk factors for severe bronchiolitis.

Conclusions: There was a significant increase in hospitalizations for RSV bronchiolitis from 2002 to 2007. A majority of the children with RSV bronchiolitis were previously healthy, but their disease severity was worse compared with those hospitalized with non-RSV bronchiolitis.

"
AUTHORS
Octavio Ramilo
Rebecca Chason
Margaret Trost
Alejandra Soriano-Fallas
Rafia Bhore
Carla G García et al
PUBLISHED

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Nosocomial respiratory syncytial virus infections in a paediatric department.
"The seasonal problem of respiratory infections in children caused by respiratory syncytial virus (RSV) is worldwide. A number of these infections are known to occur by nosocomial acquisition. In order to reduce the risk, measures, such as cohort nursing and handwashing, have been used in the paediatric department of Odense University Hospital for three years. In a retrospective evaluation of this routine practice the incidence of nosocomial RSV infections was recorded. The overall rate of nosocomial infection was low, but was proportionally highest in the unit for children aged under 6 months; no change in incidence was seen over the three-year period. In the infectious disease unit, where the majority of RSV infected children were admitted, the rate of nosocomial infection decreased despite an unchanged routine. This difference cannot be explained simply on the basis of longer hospital admission of the children under 6 months of age, but might relate to acquired immunity in children of all ages in the infectious diseases unit or better facilities for segregation within that unit."
AUTHORS
J Kamper
B Nielsen
K Siboni
B Trommer
M K Hornstrup
PUBLISHED

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Parainfluenza virus type 3 outbreak in a neonatal intensive care unit
"Parainfluenza virus (PIV) is a respiratory pathogen in young children and is second only to the respiratory syncytial virus (RSV) as a cause of lower respiratory tract infection. PIV type 3 (PIV3) is the most severe. Herein we describe an outbreak of PIV3 in three infants in a neonatal intensive care unit. They were diagnosed on virus culture from pharyngeal swabs. We prevented the spread of the virus using standard infection control procedures and isolation of the symptomatic infants. One infant had severe chronic lung disease and was complicated with recurrent wheezing for a long time. Because RSV and PIV have many structural, pathogenic, epidemiologic, and clinical similarities, we speculate that PIV infection causes recurrent wheezing, as observed with RSV infection. Therefore, physicians must consider recurrent wheezing at the time of treatment of PIV infection early in life."
AUTHORS
Yoshinobu Honda
Kentaro Haneda
Hajime Maeda
PUBLISHED

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The need of health policy perspective to protect Healthcare Workers during COVID-19 pandemic. A GRADE rapid review on the N95 respirators effectiveness.
"Background Protecting Health Care Workers (HCWs) during routine care of suspected or confirmed COVID-19 patients is of paramount importance to halt the SARS-CoV-2 (Severe Acute Respiratory Syndrome-Coronavirus-2) pandemic. The WHO, ECDC and CDC have issued conflicting guidelines on the use of respiratory filters (N95) by HCWs.
Methods We searched PubMed, Embase and The Cochrane Library from the inception to March 21, 2020 to identify randomized controlled trials (RCTs) comparing N95 respirators versus surgical masks for prevention of COVID-19 or any other respiratory infection among HCWs. The grading of recommendations, assessment, development, and evaluation (GRADE) was used to evaluate the quality of evidence.
Findings Four RCTs involving 8736 HCWs were included. We did not find any trial specifically on prevention of COVID-19. However, wearing N95 respirators can prevent 73 more (95% CI 46-91) clinical respiratory infections per 1000 HCWs compared to surgical masks (2 RCTs; 2594 patients; low quality of evidence). A protective effect of N95 respirators in laboratory-confirmed bacterial colonization (RR= 0.41; 95%CI 0.28-0.61) was also found. A trend in favour of N95 respirators was observed in preventing laboratory-confirmed respiratory viral infections, laboratory-confirmed respiratory infection, and influenza like illness.
Interpretation We found no direct high quality evidence on whether N95 respirators are better than surgical masks for HCWs protection from SARS-CoV-2. However, low quality evidence suggests that N95 respirators protect HCWs from clinical respiratory infections. This finding should be contemplated to decide the best strategy to support the resilience of healthcare systems facing the potentially catastrophic SARS-CoV-2 pandemic."
AUTHORS
Greta Castellini
Primiano Iannone
Silvia Gianola
Daniela D'Angelo
Claudio Mastroianni
Giuseppe La Torre et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Effect of various decontamination procedures on disposable N95 mask integrity and SARS-CoV-2 infectivity
"The COVID-19 pandemic has created a high demand on personal protective equipment, including disposable N95 masks. Given the need for mask reuse, we tested the feasibility of vaporized hydrogen peroxide (VHP), ultraviolet light (UV), and ethanol decontamination strategies on N95 mask integrity and the ability to remove the infectious potential of SARS-CoV-2. FIT test data showed functional degradation by both ethanol and UV decontamination to different degrees. VHP treated masks showed no significant change in function after two treatments. We also report a single SARS-CoV-2 virucidal experiment using Vero E6 cell infection. We hope our data will guide further research for evidenced-based decisions for disposable N95 mask reuse and help protect caregivers from SARS-CoV-2 and other pathogens."
AUTHORS
John Welle
Haley Hanseler
Tacy Brotherton
Jeffrey S. Smith
Nicholas L. Stucky
Carlo B. Bifulco et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Is the fit of N95 facial masks effected by disinfection? A study of heat and UV disinfection methods using the OSHA protocol fit test.
"The current COVID-19 pandemic has highlighted global supply chain shortcomings in the US hospital delivery system, most notably personal protective equipment (PPE) and COVID-19 is found on these masks ~ 7 days. Recent work from our group has shown two promising disinfection methods for N95 facial masks, dry heat (hot air (75C, 30 min) and UVGI which is UVGI 254 nm, 8W, 30 min. Using N95 five models of N95 masks from three different manufacturers we determined the following: 1) Hot air treated N95 masks applied over 5 cycles did not degrade the fit of masks (1.5% change in fit factor, p = .67), 2) UVGI treated N95 masks applied over 10 cycles were significantly degraded in fit and did not pass quantitative fit testing using OSHA testing protocols on a human model (-77.4% change in fit factor, p = .0002)."
AUTHORS
Xuanze Yu
Wang Xiao
Lei Liao
Amy DPhil Price
Yi Cui
Larry F Chu et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Literature review
Live Scoping Review of N95 and Surgical Facemask Decontamination and Reuse: A Scoping Review Protocol
"During the COVID-19 pandemic, a shortage of personal protective equipment (PPE), namely surgical masks, N95 masks, and gowns, has been experienced by some hospitals and could be expected in others due to a rapidly increased need. The Centres for Disease Control and Prevention (CDC) specifically recommends N95 filtering facepiece respirators (FFRs) for healthcare workers who are interacting with patients with COVID-19 under aerosol precautions, and when performing aerosol generating medical procedures. In contrast, surgical masks have much broader use and are recommended for use by health care providers to protect against the risk of droplet transmission in inpatient healthcare settings and outpatient settings (e.g. COVID-19 assessment centres, long-term care facilities, and community care settings). One potential method of addressing the shortage and ensuring adequate protection for health care workers in accordance with the above recommendations would be to decontaminate and reuse N95 FFRs and surgical masks. Our group recently conducted a series of systematic reviews to synthesize the existing literature on N95 and surgical mask decontamination. However, literature in this area is rapidly evolving and these systematic reviews will require updates in order to provide clinicians, hospital administrators, and public health officials with the most up-to-date and comprehensive information available. The purpose of this living scoping review is to identify all original research on N95 and surgical mask decontamination and reuse, and to build an open-access database of the existing literature."
AUTHORS
Katie O'Hearn
Margaret Sampson
Nassr Nama
Dayre McNally
David J Zorko
Lindsey Sikora et al
PUBLISHED
2020 in Center for Open Science

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Efficacy of moist heat decontamination against various pathogens for the reuse of N95 respirators in the COVID-19 emergency
"Decontamination of N95 respirators has become critical to alleviate PPE shortages for healthcare workers in the current COVID-19 emergency. The factors that are considered for the effective reuse of these masks are the fit, filter efficiency and decontamination/disinfection level both for SARS-CoV2, which is the causative virus for COVID-19, and for other organisms of concern in the hospital environment such as Staphylococcus aureus or Clostridium difficile.
The efficacy of inactivation or eradication against various pathogens should be evaluated thoroughly to understand the level of afforded disinfection. Methods commonly used in the sterilization of medical devices such as ionizing radiation, vaporized hydrogen peroxide, and ethylene oxide can provide a high level of disinfection, defined as a 6 log10 reduction, against bacterial spores, considered the most resistant microorganisms. CDC guidance on the decontamination and reuse of N95s also includes the use of moist heat (60°C, 80% relative humidity, 15-30 min) as a possible recommendation based on literature showing preservation of fit efficiency and inactivation of H1N1 on spiked masks.

Here, we explored the efficacy of using moist heat under these conditions as a decontamination method for an N95 respirator (3M 1860S, St. Paul, MN) against various pathogens with different resistance; enveloped RNA viruses, Gram (+/-) bacteria, and non-enveloped viruses."
AUTHORS
Hui Min Leung
Joseph Gardecki
Rachel L Connolly
Dmitry Gil
Keith K Wannomae
Ebru Oral et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Effect of gamma sterilization on filtering efficiency of various respiratory face-masks
"Three types of respiratory masks viz N95, non-woven fabric and double layer cotton cloth are being used as an essential inhalation protective measure against COVID-19 by suppressing the entry of respiratory droplets. The filtering efficiency of these masks were tested before and after sterilisation using gamma radiation for the two flow rate conditions corresponding normal breath rate (20lpm) and during sneezing/coughing (90lpm).Sterilisation is carried out using a gamma irradiator containing Co-60 source for the two dose exposures viz. 15kGy and 25kGy. The filtering efficiency for surgical (non-woven fabric) and double layer cotton cloth mask is found to vary from 18% to 22% for the cumulative particle of size ≥ 0.3 micron in both un-irradiated and irradiated condition. The filtration efficiency of N95 mask is found to be reduced to 70% for the most penetrating particle size (0.3 micron) with the flow rate of 20lpm and further reduced for particles in the range of 0.1 and 0.2 micron with flow rate of 90 lpm. The reduction in efficiency after gamma sterilization is associated with reduction of electrostatic interaction of filter medium with particles laden in the air stream. Even with reduced filtering efficiency due to gamma sterilisation, the N95 masks are much superior than the surgical and cloth masks. Instead of disposing N95 mask after single use, they can be reused a few times as N70 mask during this pandemic crisis after sterilisation using gamma radiation."
AUTHORS
B. Venkatraman
V. Subramanian
M. Menaka
Ramani Yuvaraj
D. N. Saneetha
Amit Kumar
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Effect of gamma sterilization on filtering efficiency of various respiratory face-masks
"Abstract
Three types of respiratory masks viz N95, non-woven fabric and double layer cotton cloth are being used as an essential inhalation protective measure against COVID-19 by suppressing the entry of respiratory droplets. The filtering efficiency of these masks were tested before and after sterilization using gamma radiation for the two flow rate conditions corresponding normal breath rate (20 lpm) and during sneezing/coughing (90 lpm). Sterilization is carried out using a gamma irradiator containing Co-60 source for the two dose exposures viz. 15kGy and 25kGy. The filtering efficiency for surgical (non-woven fabric) and double layer cotton cloth mask is found to vary from 18% to 22% for the cumulative particle of size ≥ 0.3µm in both un-irradiated and irradiated condition.The filtration efficiency of N95 mask is found to be reduced to 70% for the most penetrating particle size (0.3 µm) with the flow rate of 20 lpm and further reduced for particles in the range of 0.1 and 0.2µm with flow rate of 90 lpm. The reduction in efficiency after gamma sterilization is associated with reduction of electrostatic interaction of filter medium with particles laden in the air stream.Even with reduced filtering efficiency due to gamma sterilization, the N95 masks are much superior than the surgical and cloth masks.Instead of disposing N95 mask after single use, they can be reused a few times as N70 mask during this pandemic crisis after sterilization using gamma radiation."
AUTHORS
B. Venkatraman
V. Subramanian
M. Menaka
Ramani Yuvaraj
D.N. Sangeetha
Amit Kumar
PUBLISHED
2020 in Research Square

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Facial Skin Temperature and Discomfort When Wearing Protective Face Masks: Thermal Infrared Imaging Evaluation and Hands Moving the Mask
"Individual respiratory protective devices and face masks represent critical tools in protecting health care workers in hospitals and clinics, and play a central role in decreasing the spread of the high-risk pandemic infection of 2019, coronavirus disease (COVID-19). The aim of the present study was to compare the facial skin temperature and the heat flow when wearing medical surgical masks to the same factors when wearing N95 respirators. A total of 20 subjects were recruited and during the evaluation, each subject was invited to wear a surgical mask or respirator for 1 h. The next day in the morning at the same hour, the same subject wore a N95 mask for 1 h with the same protocol. Infrared thermal evaluation was performed to measure the facial temperature of the perioral region and the perception ratings related to the humidity, heat, breathing difficulty, and discomfort were recorded. A significant difference in heat flow and perioral region temperature was recorded between the surgical mask and the N95 respirator (p &lt; 0.05). A statistically significant difference in humidity, heat, breathing difficulty, and discomfort was present between the groups. The study results suggest that N95 respirators are able to induce an increased facial skin temperature, greater discomfort and lower wearing adherence when compared to the medical surgical masks."
AUTHORS
Antonio Scarano
Felice Lorusso
Francesco Inchingolo
PUBLISHED
2020 in International Journal of Environmental Research and Public Health

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Vaporized H2O2 decontamination against surrogate viruses for the reuse of N95 respirators in the COVID‐19 emergency
"Decontamination of N95 respirators has become critical to alleviate PPE shortages for healthcare workers in the current COVID-19 emergency. The factors that are considered for the effective reuse of these masks are the fit, filter efficiency and decontamination/disinfection level both for SARS-CoV-2, which is the causative virus for COVID-19, and for other organisms of concern in the hospital environment such as Staphylococcus aureus or Clostridium difficile.
In its guidance entitled ′Recommendations for Sponsors Requesting EUAs for Decontamination and Bioburden Reduction Systems for Surgical Masks and Respirators During the Coronavirus Disease 2019 (COVID19) Public Health Emergency′ (May 2020)[1], the FDA recommends a 6-log10 reduction in either the most resistant bacterial spores for the system or in a mycobacterium species to authorize the use of a decontamination method of N95 respirators for single or multiple users. While the goal is primarily inactivation against SARS-CoV-2, testing of decontamination methods against the virus may not always be available. For decontamination methods considered for only single users, the recommendation is a 6-log10 reduction in the infective virus concentration of 3 non-enveloped viruses or in the concentration of two Gram (+) and two Gram (-) bacteria. Based on these recommendations, we explored the efficacy of vaporized H2O2 (VHP) treatment of N95 respirators against surrogate viruses covering a wide range of disinfection resistance for emergency decontamination and reuse to alleviate PPE shortages for healthcare workers in the COVID-19 emergency."
AUTHORS
Cassidy Collins
Ralph Jones
John Durkin
Orhun K Muratoglu
Hui Min Leung
Joseph A Gardecki et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Characterization of a novel, low-cost, scalable vaporized hydrogen peroxide system for sterilization of N95 respirators and other COVID-19 related personal protective equipment.
"Due to the virulence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pathogen responsible for the respiratory disease termed COVID-19, there has been a significant increase in demand for surgical masks and N95 respirators in medical clinics as well as within communities operating during the COVID-19 epidemic. Thus, community members, business owners, and even medical personnel have resorted to alternative methods for sterilizing face coverings and N95 respirators for reuse. While significant work has shown that vaporized hydrogen peroxide (VHP) can be used to sterilize N95 respirators, the cost and installation time for these sterilization systems limit their accessibility. To this end, we have designed and constructed a novel, cost-effective, and scalable VHP system that can be used to sterilize N95 respirators and other face coverings for clinical and community applications. N95 respirators inoculated with P22 bacteriophage showed a greater than 6-log10 reduction in viral load when sterilized in the VHP system for one 60-minute cycle. Further, N95 respirators treated with 20 cycles in this VHP system showed comparable filtration efficiency to untreated N95 respirators in a 50 to 200 nanometer particulate challenge filtration test. While a 23% average increase in water droplet roll-off time was observed for N95 respirators treated with 5 cycles in the sterilization, no breakdown in fluid resistance was detected. These data suggest that our VHP system is effective in sterilizing N95 respirators and other polypropylene masks for reuse. Relating to the present epidemic, deployment of this system reduces the risk of COVID-19 community transmission while conserving monetary resources otherwise spent on the continuous purchase of disposable N95 respirators and other face coverings. In summary, this novel, scientifically validated sterilization system can be easily built at a low cost and implemented in a wide range of settings."
AUTHORS
Nikhil Dave
Mark Naufel
Tyler Smith
Clinton Ewell
Josh Chang
Sabrina Jimena Mora et al
PUBLISHED
2020 in Cold Spring Harbor Laboratory

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Are cloth masks as effective as surgical masks at reducing the risk of contracting viruses that cause respiratory disease?
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Do adults get sick from COVID-19 more often than children?
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Do cloth masks reduce the risk of contracting viruses that cause respiratory disease?
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Does air pollution accelerate the spread of COVID-19?
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Does air pollution increase the severity of symptoms from COVID-19?
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