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Masks work against COVID, finds a huge randomized trial

nature.com

Sep 3, 2021

Evidence that masks work against COVID

A huge randomized study offers evidence that wearing masks reduces the spread of COVID-19, and that surgical masks work even better than cloth ones. The ambitious study involved more than 340,000 people in 600 villages in Bangladesh. Villages and households were randomly assigned to receive free cloth or surgical masks and other mask-promotion strategies, or no interventions at all. Researchers observed the impact on people’s behaviour at hotspots such as tea stalls and markets. Participants were quizzed about any coronavirus symptoms, and symptomatic individuals were tested for SARS-CoV-2 infection.

The interventions tripled the proportion of people who wore masks correctly. Overall, in the villages where the team distributed masks, symptomatic infections were 9.3% lower. Where surgical masks were given out, the results were even better: infections dropped by 11%. Older people benefited most: symptomatic COVID-19 in people over 60 went down by 35% in the villages using surgical masks.