Association of social distancing and masking with risk of COVID-19

Kwon, Sohee; Joshi, Amit D.; Lo, Chun-Han; Drew, David A.; Nguyen, Long H.; Guo, Chuan-Guo; Ma, Wenjie; Mehta, Raaj S.; Warner, Erica T.; Astley, Christina M.; Merino, Jordi; Murray, Benjamin; Wolf, Jonathan; Ourselin, Sebastien; Steves, Claire J.; Spector, Tim D.; Hart, Jaime E.; Song, Mingyang; VoPham, Trang; Chan, Andrew T.

Given the continued burden of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) disease (COVID-19) across the U.S., there is a high unmet need for data to inform decision-making regarding social distancing and universal masking. We examined the association of community-level social distancing measures and individual masking with risk of predicted COVID-19 in a large prospective U.S. cohort study of 198,077 participants. Individuals living in communities with the greatest social distancing had a 31% lower risk of predicted COVID-19 compared with those living in communities with poor social distancing. Self-reported masking was associated with a 63% reduced risk of predicted COVID-19 even among individuals living in a community with poor social distancing. These findings provide support for the efficacy of mask-wearing even in settings of poor social distancing in reducing COVID-19 transmission. In the current environment of relaxed social distancing mandates and practices, universal masking may be particularly important in mitigating risk of infection.