Stanford Medicine says it “strongly supports the use of face masks to control the spread of COVID-19.” Yet viral stories falsely claim a “Stanford study” showed that face masks are unsafe and ineffective against COVID-19. The paper is a hypothesis, not a study, from someone with no current affiliation with Stanford. Update: The paper was retracted.
A study from the Centers for Disease Control and Prevention found that state-issued mask mandates were associated with significant decreases in daily COVID-19 case and death growth rates. Yet some conservative outlets and social media users falsely claim the study shows mask mandates have a negligible impact on COVID-19 outcomes.
Multiple lines of evidence back the use of face masks to limit the spread of the coronavirus.
Lab tests, for example, show that masks can partially block exhaled respiratory droplets, which are thought to be the primary way the virus spreads. Analyses of people who came into contact with those with COVID-19 have also found mask-wearing to be associated with a reduced risk of contracting the virus. Numerous studies similarly document an association between self-reported mask wearing and control of the virus in a community or the implementation of a mask mandate and a subsequent decline in COVID-19 cases.
Headlines shared on social media distort the facts of a recent order by the Centers for Disease Control and Prevention that mandates face masks be worn on public transportation. The order doesn’t require that individuals wear two masks. CDC guidance issued with the order does say that cloth masks should be made of at least two layers.