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
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
Massive randomized study is proof that surgical masks limit coronavirus spread, authors say
The authors of a study based on an enormous randomized research project in Bangladesh say their results offer the best evidence yet that widespread wearing of surgical masks can limit the spread of the coronavirus in communities.

The preprint paper, which tracked more than 340,000 adults across 600 villages in rural Bangladesh, is by far the largest randomized study on the effectiveness of masks at limiting the spread of coronavirus infections.

Its authors say this provides conclusive, real-world evidence for what laboratory work and other research already strongly suggest: mask-wearing can have a significant impact on limiting the spread of symptomatic covid-19, the disease caused by the virus.

“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 who helped lead the study, said in an interview, calling it “a nail in the coffin” of the arguments against masks.


The researchers estimate that among a group of Bangladeshi adults in the study that were encouraged to wear masks, mask-wearing increased by 28.8 percent after the intervention. When tracked, this group saw a 9.3 percent reduction in symptomatic covid-19 seroprevalence, meaning the virus was confirmed by bloodwork, as well as a further 11.9 percent reduction in covid-19 symptoms.

... “I think a big error would be to read this study and to say, ‘Oh, masks can only prevent 10 percent 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 authors granted journalists an early look at the results because of their potential importance in global public health debates.

Independent experts that were asked to look at the research praised its scale; some suggested that it might be the most convincing argument yet for mask-wearing.

“This is an incredibly challenging but important study to pull off,” said Megan L. Ranney, an emergency medicine physician and professor at Brown University who was not involved with this research. “Anti-mask people keep saying, ‘Where’s the randomized controlled trial?’ Well, here you go.”

“It’s not just modeling or looking back at studies,” said Lawrence Gostin, faculty director of the O’Neill Institute for National and Global Health Law at Georgetown University, who also was not involved. “This is the gold standard of scientific knowledge.”


... The study does not quite claim to be the final word on masks. The authors 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 emphasized, 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.

Abaluck also noted that the intervention group was found to practice more social distancing, which may complicate the findings on masks. However, he noted that in locations such as mosques, where many participants worshiped, there was “no physical distance,” along with poor indoor ventilation — but there was increased mask-wearing.
Read the full article: https://www.washingtonpost.com/world/2021/09/01/masks-study-covid-bangladesh/