Surgical masks limit coronavirus spread, massive study shows
A study involving more than 340,000 people in Bangladesh offers some of the strongest real-world evidence yet that mask use can help communities slow the spread of Covid-19.
The research, conducted across 600 villages in rural Bangladesh, is the largest randomized trial to demonstrate the effectiveness of surgical masks, in particular, to curb transmission of the coronavirus.
Though previous, smaller studies in laboratories and hospitals have shown that masks can help prevent the spread of Covid, the new findings demonstrate that efficacy in the real world — and on an enormous scale.
"This is really solid data that combines the control of a lab study with real-life actions of people in the world to see if we can get people to wear masks, and if the masks work," said Laura Kwong, an assistant professor of environmental health sciences at the University of California, Berkeley, and one of the co-authors of the study.
The preprint study was posted online Wednesday by the nonprofit organization Innovations for Poverty Action and is currently undergoing peer review. The research was led by Kwong, Jason Abaluck and Mushfiq Mobarak from Yale University, and Steve Luby and Ashley Styczynski from Stanford University.
The study's findings have important implications for countries that are relying on mitigation measures to slow the virus's spread until vaccines are more readily available. But there are also applicable lessons for nations like the United States, where some communities are reimposing mask mandates to stem outbreaks of the delta variant.
"The policy question we were trying to answer was: If you can distribute masks and get people to wear them, do they work?" said study co-author Mushfiq Mobarak, a professor of economics at Yale.
For five months beginning last November, Mobarak and his colleagues tracked 342,126 adult Bangladeshis and randomly selected villages to roll out programs to promote their usage, which included distributing free masks to households, providing information about their importance and reinforcing their use in the community.