A systematic review published in October 2020 discusses the controversy with mask use in stopping the spread of COVID-19. Overall, evidence thoroughly supports using masks, with recent studies suggesting that they could save lives in different ways: reducing transmitting and catching the coronavirus, as well as reducing the severity of infection in those who catch it. A preprint released in August 2020 (not yet peer-reviewed and published) found weekly increased in per-capita mortality were four times lower in places where masks were the norm or recommended by the government, compared with other regions globally. Another study looked at the effects of US state-government mandates for mask use in April and May. The results determined that mask mandates reduced the growth of COVID-19 cases by up to 2 percentage points per day. A conservative estimate is that mask mandates may have prevented as many as 450,000 cases, after controlling for other mitigation measures, such as physical distancing. The general consensus among scientists is that masks are not infallible, but they work. [1]
A 2020 systematic review found that masks may be more protective for well individuals in the community and in the healthcare setting, and that respirators are more protective than medical masks which are more protective than cloth masks. Nineteen papers were selected for this review, consisting of eight of mask use in the community, six by healthcare workers, and five laboratory studies (source control). In the community, masks appeared to be effective with and without hand hygiene, and both together are more protective than control. Medical masks were not as effective as continuous N95 use in healthcare workers, and cloth masks may not be effective in healthcare settings. Source control studies found surgical and N95 masks to be effective in preventing viral spread. This review did show the use of masks by sick patients is likely protective, and coronaviruses are not exhaled in surgical mask wearers. [2]
A 2020 meta-analysis evaluated the effectiveness of the use of masks to prevent laboratory-confirmed respiratory virus transmission by using case-control studies, cluster-randomized trials, and cohort studies. The use of masks provided a significant protective effect (odds ratio [OR] 0.35, 95% confidence interval [CI] 0.24-0.51) against the spread of respiratory viruses. The majority of studies evaluated healthcare workers, and the analysis found masks can reduce respiratory virus infection by 80% (OR 0.20, 95% CI 0.11 to 0.37). This benefit was also seen in non-healthcare workers, with a 47% reduction (OR 0.53, 95% CI 0.36 to 0.79). This analysis included not only surgical masks study but also four studies specific to N95 respirator use. [3]
In September 2020, the Centers for Disease Control and Prevention published a study on contact exposures associated with COVID-19 among outpatient adults. There has been misinformation extrapolated from these results suggesting that 85% of mask wearers still contract COVID-19. This was a case-control study that aimed to assess community and close contact exposures associated with COVID-19 reported by symptomatic patients who tested positive (n=154) compared with symptomatic patients who tested negative (n=160). Of the 154 participants who tested positive, a total of 85% said they had worn a mask either "always" (70.6%) or "often" (14.4%) over the 14 days prior to the onset of their illness; of those who did not test positive, a total of 88.7% said they had worn a mask either "always" (74.2%) or "often" (14.5%). This corresponded to a non-significant difference (P=0.86). Of the positive patients, 40.9% reported going to a restaurant 14 days before exposure and 85.6% reported shopping 14 days before exposure. This study was not designed to determine the efficacy of masks or even to determine how many people who wear masks contract COVID-19. Additionally, this is based on patient-reported data that may be unreliable; there is no way to tell how adherent the participants were in mask-wearing or if the masks were worn correctly. [4]