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Masks, especially surgical masks, significantly reduce the risk of contracting Covid-19. Getting more people to wear them – through warrants or strategies like handing out masks in churches and other public events – could save thousands of lives every day around the world and hundreds every day in the world. United States.

While it may seem like common sense more than 18 months after the start of the pandemic, the first studies of masking had raised important questions. Mask warrants seemed to reduce Covid-19 cases, but was it because of masking, or because people in places with mask warrants would have become more cautious even without them? Because of this uncertainty, some governments and public health agencies were reluctant to recommend them. That’s why we conducted one of the largest and most sophisticated studies of mask wearing, using the research design’s gold standard, a randomized controlled trial, to assess whether communities where more people wearing masks have fewer cases of Covid-19.

Many people live in countries where vaccines are not yet widely available. Even in the United States, vaccines are available but used unevenly, and the weekly death rate from Covid-19 remains high. In both of these environments, masks are an essential and inexpensive tool in the fight against the coronavirus.

Our research, which is currently under peer review, was conducted among 340,000 adults in 600 villages in Bangladesh and tested many different strategies for getting people to wear masks.

Our research team decided to distribute masks directly to people’s homes and in crowded public places like mosques and markets. We provided information on why wearing a mask was important and involved religious and community leaders in this post. Finally, we asked the residents of each village to politely ask anyone not wearing a mask to put one on and to give masks to those in need.

Although not everyone agreed to mask themselves, mask wearing increased by around 30 percentage points among adults who were encouraged to do so. This change resulted in an overall 9% reduction in Covid-19. In communities where we have promoted the use of surgical masks, Covid-19 cases have fallen by 11%.

Our study did not measure the effect of wearing the universal mask but the effect of a voluntary mask program. This resulted in an increase of four in 10 people using a mask versus one in 10 masking – a big increase in use, but still far from perfect. If everyone wore masks, the reductions in Covid-19 cases would most likely have been significantly greater.

People over 50 have benefited the most, especially in the communities where we have distributed surgical masks. In these communities, Covid-19 cases have decreased by 23% for people aged 50 to 60 and by 35% for people over 60. Our study does not suggest that alone older people must wear masks, but instead this widespread wearing of community masks reduces the risk of Covid-19, especially for older people.

Let’s put this in concrete terms. Our best estimate is that every 600 people who wear surgical masks in public spaces prevent an average of one death per year given recent death rates in the United States. Think of a church with 600 members. If a congregation found out that it could save a member’s life, would everyone agree to wear surgical masks in indoor public spaces for the next year?

We also tested the filtration of surgical masks that had been worn, crumpled in pockets and purses, and washed with soap and water up to 10 times. These masks always prevented more virus particles from passing through than typical fabric masks. Masks with even better filtration or fit than surgical masks, such as the KF94 or KN95 masks, can offer even stronger protection than surgical masks if worn correctly.

The bottom line is that masks work, and better quality masks most likely work better at preventing Covid-19. If you have the option of choosing between a cloth and a surgical mask, go for surgery. But the best mask is one that a person will wear and wear correctly.

Wearing a mask does not need to be permanent. More surgical masks in high risk areas today may mean less need for masks tomorrow, thus avoiding many deaths along the way. In places where mask warrants are not feasible or possible, gentler alternatives – like a host handing out masks at the entrance of a mall – can be remarkably effective. Our research suggests that if they are given a mask and politely asked to please wear one, many people will. Not everyone will, but not everyone needs to do it in order for lives to be saved.

Mr. Abaluck is Professor of Economics at Yale University School of Management. Ms. Kwong is an Assistant Professor of Environmental Health Sciences at the Berkeley School of Public Health at the University of California. Dr Luby is Professor of Medicine in the Division of Infectious Diseases at Stanford University.

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