Does a surgical mask worn by a person infected with COVID-19 reduce the chance that the infected person will spread COVID-19 to others?

Last updated: February 20, 2022
Yes. Both studies in this list that examine the question agreed on this conclusion. We identified both studies as literature reviews, which are studies that review and often evaluate the findings of many studies on a question. This gives us more confidence that the answer is correct.
This short answer was generated by aggregating the answers that each of the 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.
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Chart summary of 2 studies examining this question

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All labels of Literature Reviews and source quality are assigned by State of K. All labels of High Quality Source are assigned based on whether the publication in which the article appeared was ranked as Q1 by Scimago Institutions Rankings. Certain well-regarded think tanks are also given this label.

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:

SUMMARIES OF STUDIES
Total studies in list: 2
Sorted by publication year
1
An evidence review of face masks against COVID-19
"The science around the use of masks by the public to impede COVID-19 transmission is advancing rapidly. In this narrative review, we develop an analytical framework to examine mask usage, synthesizing the relevant literature to inform multiple areas: population impact, transmission characteristics, source control, wearer protection, sociological considerations, and implementation considerations. A primary route of transmission of COVID-19 is via respiratory particles, and it is known to be transmissible from presymptomatic, paucisymptomatic, and asymptomatic individuals. Reducing disease spread requires two things: limiting contacts of infected individuals via physical distancing and other measures and reducing the transmission probability per contact. The preponderance of evidence indicates that mask wearing reduces transmissibility per contact by reducing transmission of infected respiratory particles in both laboratory and clinical contexts. Public mask wearing is most effective at reducing spread of the virus when compliance is high. Given the current shortages of medical masks, we recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies. Because many respiratory particles become smaller due to evaporation, we recommend increasing focus on a previously overlooked aspect of mask usage: mask wearing by infectious people (“source control”) with benefits at the population level, rather than only mask wearing by susceptible people, such as health care workers, with focus on individual outcomes. We recommend that public officials and governments strongly encourage the use of widespread face masks in public, including the use of appropriate regulation."
AUTHOR
Jeremy Howard,
PUBLISHED
2021 PNAS
Literature Review
Yes
Yes
2
How effective is a mask in preventing COVID-19 infection?
"The main clinical characteristics of COVID-19 are respiratory symptoms that can lead to serious cardiovascular damages and severe worsening of other medical conditions. One of the major strategies in preparedness and response to COVID 19 is effective utilization of personal protective equipment (PPE) among which the masks of different kinds are on the top of the list especially for activities in the public places. However, the underlying mechanisms of masks in preventing virus transmission have not been well identified and the current experimental data still show inconsistent outcomes that may mislead the public. For instance, the early understanding of the mask functions was limited especially in the escalating phase of the COVID 19 pandemic, resulting in quite controversial remarks on masks. Although extensive studies in mask functions have been carried out ever since the COVID-19 outbreaks, most of the investigations appear to have focused on exhalation isolation of individuals who may have been infected with the disease. Less emphasis was laid on inhalation protection from virus transmission, an important aspect that undergirds the public health policies and protective strategies. This review provides the most up-to-date information on the transmission modes of COVID-19 virus in terms of droplets and aerosols. The roles of masks in disease prevention and transmission reduction are evaluated on various types, structures and functions. More important, both aspects of exhalation isolation and inhalation protection are discussed based on virus transmission modes and the effectiveness of different types of masks under varied environmental conditions."
AUTHOR
Yuxin Wang
PUBLISHED
2020 Medical Devices & Sensors
Literature Review
Yes
Yes