The randomly assigned pro-masking policy reduced the number of confirmed, symptomatic COVID-19 cases in the intervention group by nearly 10 percent, relative to the control group. That might not sound like a huge effect. But the intervention increased masking from 14 percent to only 43 percent; 100 percent masking would have likely had a much larger effect.
Even more impressively, the villages that implemented pro-masking policies saw a 34 percent decline in COVID-19 among seniors, for whom the disease is most deadly. This could be because older villagers are more likely to properly wear masks, or because they are more likely to have symptomatic infections if they come into contact with the coronavirus.
The study also found clear evidence that surgical masks are better at reducing the spread of symptomatic COVID-19 than cloth masks. In focus groups, Bangladeshi participants said they preferred cloth masks because they seemed to be more durable. But the researchers found that, on the one hand, surgical masks were more efficient, even after being washed 10 times with soap and water. “On the other hand, we found only mixed evidence about cloth masks,” Jason Abaluck, a co-author of the study and a professor at Yale, told me. People wearing cloth masks had fewer symptoms, such as coughs, than the control group, which suggests some effect. But cloth-mask wearers didn’t have significantly fewer coronavirus antibodies as determined by blood tests. “We cannot reject that [cloth masks] have zero or only a small impact on symptomatic SARS-CoV-2 infections,” Abaluck wrote along with Mushfiq Mobarak of Yale, Laura Kwong of UC Berkeley, Stephen Luby and Ashley Styczynski of Stanford, and other researchers.
Original Article: https://www.theatlantic.com/ideas/archive/2021/09/masks-were-working-all-along/619989/
Written by Derek Thompson