The widespread wearing of surgical masks can limit the spread of coronavirus in communities, more than masks made of cloth, finds a large study.

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Researchers from Yale University, US, tracked more than 340,000 adults across 600 villages in rural Bangladesh. The findings, published as a preprint, showed that mask-wearing can have a significant impact on limiting the spread of symptomatic COVID-19, the Washington Post reported.

"I think this should basically end any scientific debate about whether masks can be effective in combating COVID at the population level," Jason Abaluck, an economist at Yale, was quoted as saying. Abaluck called the study "a nail in the coffin" of the arguments against masks.

Mask wearers saw a 9.3 per cent reduction in symptomatic COVID-19 seroprevalence, meaning the virus was confirmed by bloodwork, as well as a further 11.9 per cent reduction in COVID-19 symptoms. However, the team emphasised that this did not mean masks were only 9.3 per cent effective.

"I think a big error would be to read this study and to say, 'Oh, masks can only prevent 10 per cent of symptomatic infections'," Abaluck said. The number would probably be several times higher if masking were universal, he said. The study is under peer review with the journal Science, the Post reported.

Further, the researchers found that while cloth masks clearly reduced symptoms, they "cannot reject" the idea that, unlike surgical masks, they may have only a small effect on symptomatic coronavirus infections, and possibly none at all. Abaluck emphasised, however, that research did not produce evidence that cloth masks are ineffective. The results "don't necessarily show that surgical masks are much, much better than cloth masks, but we find much clearer evidence of the effectiveness in surgical masks", he said.