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Scientists Study How Much A Difference Wearing A Mask Makes


For weeks now, wearing a mask has been politicized here in the United States. But that may be changing. President Trump tweeted out a photo of himself wearing a mask and calling it patriotic yesterday afternoon. Twenty-five states plus the District of Columbia now have mask mandates. And many retail stores are requiring them. In a moment, we're going to ask Dr. Anthony Fauci what we can do to turn the tide on the pandemic here in the United States. But first, NPR's global health correspondent Nurith Aizenman reports on the science of masks.

NURITH AIZENMAN, BYLINE: For months, scientists have been poring over data from across the globe - China, Japan, Germany, the U.S. - to compare what's happened in places where most people use masks versus places where most do not. Ali Mokdad is on a research team that's tried to make sense of all these studies. He's with the University of Washington's Institute for Health Metrics and Evaluation.

ALI MOKDAD: You take every study that has been published on the protective effect of masks, and then you reanalyze all the data.

AIZENMAN: And they came up with a bottom-line estimate. If 95% of people wear cotton masks when they're interacting with other people, it reduces transmission by 30%. In other words, each infected person will go on to infect 30% fewer people. In fact, says Mokdad...

MOKDAD: The mask could be even more powerful.

AIZENMAN: Because that's assuming everyone is just wearing cloth masks, not surgical masks or N95s, which are even more effective. Then Mokdad and his colleagues ran a simulation. Based on the pandemic's current trajectory through the U.S., they forecast that by November 1, about 85,000 more people will die from COVID-19. But if 95% of Americans start wearing cloth masks...

MOKDAD: We find that 40,000 of these mortalities could be avoided between now and November 1.

AIZENMAN: And there's more. Based on the U.S. experience this past spring, Mokdad's team have come up with an estimate for how bad it would need to get for U.S. officials to return to full-on lockdown. Texas is just a month away. But if everyone there started wearing masks right now, they just might avoid it. Ashish Jha of Harvard largely agrees.

ASHISH JHA: Look. We've never tried to use masks as our primary strategy when outbreaks are this bad. But I do believe that if we want to avoid a complete lockdown, we've got to at least give it a shot.

AIZENMAN: Jha, who directs the university's Global Health Institute, helped build a tool for counties and states to determine when the virus is spreading fast enough that the only way to get a handle on it is to revert to stay-at-home mode. And yet, he says...

JHA: If you look at the hottest of the hot spots in America - the Arizona, Texas, Florida, South Carolina - I think there may be a window.

AIZENMAN: Of course, this would require a major change in Americans' behavior. Some estimates suggest only 40% currently wear masks nationwide. Natalie Dean, a biostatistician at University of Florida, says this is one of many reasons she's wary of focusing too heavily on masks.

NATALIE DEAN: It's the idea that if we just did this one thing perfectly, that we would be fine. But I think the real solution is going to be doing a lot of things OK.

AIZENMAN: Nurith Aizenman, NPR News. Transcript provided by NPR, Copyright NPR.