evidence: In some ways, that basic takeaway hasn’t changed much. Benjamin Cowling, an epidemiologist at the University of Hong Kong, told us that "there is good mechanistic evidence from laboratory studies that masks should have an effect on transmission" and that "evidence from randomized trials has not been consistent with a large effect of masks on transmission, but has been consistent with a small effect of masks on transmission." [...] Other indirect evidence comes from studies that have documented associations 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 or rates of hospitalization. [...] "We found clear evidence that surgical masks are effective in reducing symptomatic seroprevalence of SARS-CoV-2. Although cloth masks clearly reduce symptoms, we find less clear evidence of their impact on symptomatic SARS-CoV-2 infections," the authors wrote. "Our results should not be taken to imply that mask-wearing can prevent only 10% of COVID-19 cases, let alone 10% of COVID-19 mortality. Our intervention induced 29 more people out of every 100 to wear masks, with 42% of people wearing masks in total. The total impact with near-universal masking — perhaps achievable with alternative strategies or stricter enforcement — may be several times larger than our 10% estimate."