The general public can use cloth masks to protect against infection spread in the community. In community settings, masks may be used in 2 ways. First, they may be used by sick persons to prevent spread of infection (source control), and most health organizations (including WHO and CDC) recommend such use. In fact, a recent CDC policy change with regard to community use of cloth masks (
1) is also based on high risk for transmission from asymptomatic or presymptomatic persons (
32). According to some studies, ≈25%–50% of persons with COVID-19 have mild cases or are asymptomatic and potentially can transmit infection to others. So in areas of high transmission, mask use as source control may prevent spread of infection from persons with asymptomatic, presymptomatic, or mild infections. If medical masks are prioritized for healthcare workers, the general public can use cloth masks as an alternative. Second, masks may be used by healthy persons to protect them from acquiring respiratory infections; some randomized controlled trials have shown masks to be efficacious in closed community settings, with and without the practice of hand hygiene (
33). Moreover, in a widespread pandemic, differentiating asymptomatic from healthy persons in the community is very difficult, so at least in high-transmission areas, universal face mask use may be beneficial. The general public should be educated about mask use because cloth masks may give users a false sense of protection because of their limited protection against acquiring infection (
16). Correctly putting on and taking off cloth masks improves protection (
Table). Taking a mask off is a high-risk process (
34) because pathogens may be present on the outer surface of the mask and may result in self-contamination during removal (
31).
https://wwwnc.cdc.gov/eid/article/26/10/20-0948_article