"We examined the association between face masks and risk of infection with SARS-CoV-2 using cross-sectional data from 3,209 participants in a randomized trial exploring the effectiveness of glasses in reducing the risk of SARS-CoV-2 infection. Face mask use was based on participants’ response to the end-of-follow-up survey. We found that the incidence of self-reported COVID-19 was 33% higher in those wearing face masks often or sometimes, and 40% higher in those wearing face masks almost always or always, compared to participants who reported wearing face masks never or almost never."
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