As academic fights go, the dispute over a recent paper about face masks and how they help prevent coronavirus spread is a pretty hot one.
"It is absolutely riddled with errors," says Harvard T.H. Chan School of Public Health epidemiologist Caroline Buckee, "and would not have gotten through standard peer review."
She and more than 40 other researchers are calling for the paper to be retracted, a rare and dramatic move in the world of science journals.
But its authors stand by their finding that in China, Italy and New York, face coverings appeared to be the most effective way to stem the spread of the virus, when added to other measures.
"It’s the very best thing," said senior author Mario Molina, a Nobel Prize laureate in chemistry, "particularly if the recommendation is also to use social distancing and be particularly careful not to go to meetings where you are very crowded with other people."
Molina’s work has focused on tiny particles in air pollution, and he emphasizes the importance of masks for blocking tiny airborne particles that people emit as they speak. So a mask doesn’t just keep sick people from spewing big droplets, he argues; it helps protect the person who wears it from incoming airborne virus.
"You use the face mask so that you don’t catch the infection," he said. "It’s not just so that you don’t propagate it to other people. So that’s crucial to convince people to use it."
Molina’s team has submitted a defense of the paper to Proceedings of the National Academy of Sciences, which says it is currently considering the dispute.
Meanwhile, more new research has been finding a strong correlation between mask-wearing and local rates of coronavirus infections, including a state-by-state analysis in the journal Health Affairs. More masks seem to mean fewer cases, and more relaxed mask-wearing appears to lead to to higher rates of infection.
Around the country, some people are resisting the advice from public health experts to wear masks. But among researchers in Massachusetts and beyond, there's a different debate underway, about whether masks might in fact be the most effective of all the current defenses against the virus.
Countries with very strong mask-wearing cultures continue to kick our butts.Shan Soe-Lin, Pharos Global Health Advisors
"The strongest evidence is the real-life examples we see on really big population samples," says Shan Soe-Lin, managing director of Pharos Global Health Advisors, a nonprofit that advises governments and philanthropies. "Countries with very strong mask-wearing cultures continue to kick our butts."
Take a look at Hong Kong, for example, says Harvard T.H. Chan School of Public Health epidemiologist Michael Mina.
"Hong Kong is extraordinarily densely populated, but it really didn’t have any big outbreaks," he says. "And that’s probably, I think, more due to mask-wearing than exceptional contact tracing."
As more data comes in, Mina and others have been modeling the difference that masks and other measures make in an outbreak.
"If you ask me my opinion about what’s the simplest, most effective option? Mask-wearing," Mina says. "I think there’s no doubt about that."
If everyone wore masks, he says — which is unlikely given American culture, but if they did — it would probably keep outbreaks under control. He estimates that if two people are wearing masks, the risk that one will infect the other drops by over 90%.
"So in that sense, I think mask-wearing alone can be a game-changer," he says, "if we as a society collectively decide that we will adhere to those rules."
Just four months ago, health authorities were conveying the opposite message, telling the public not to wear masks. But medical historian Dr. Howard Markel from the University of Michigan says that advice came against the backdrop of a mask shortage for health care workers.
And, though masks were recommended for the public as far back as the 1918 flu, scientists have debated heatedly for decades how well they really work against viruses. Markel says the pandemic sped up that science.
"A lot of studies were being done, at warp speed," he says, "and the studies were actually quite positive that wearing masks could make a difference. Not the only difference — we have to do a lot of other things — but why not?"
That shift could be compared to the research on condoms that went into overdrive because of AIDS, says Robert Hecht, president of Pharos Global Health Advisors, who has worked on HIV for 30 years. It was long known that condom use offered protection against sexually transmitted diseases, he says, but it wasn't until HIV hit that research into their benefits ramped up and "that we really understood how good a potent, protective measure it was."
Mask-wearing, he says, may not offer perfect protection, "but the cost of doing it to individuals and society is so low — it's a travesty, really, not to do it."
There’s still much to learn about how well masks protect against the coronavirus. Harvard epidemiologist Caroline Buckee, who challenges that recently published paper, says it’s hard to quantify the impact that wearing masks has.
"However, we believe, based on plausible, logical arguments, that it might be very effective," she says, "so it’s definitely worth doing."
It doesn't really matter whether masks are the very best defense, says Dr. Jeremy Faust from Brigham and Women’s Hospital, who edits a daily summary on COVID-19 research called Brief19.
"This is not the Olympics," he says. "It’s not, 'If you didn’t win the gold medal, no one will ever remember you.' It’s: 'You made the podium!' "
Even with much still unknown, he says, it’s increasingly clear that masks do help protect against the virus, and so wearing them is a patriotic service.
Markel compares the multiple protective measures people can take to layers of Swiss cheese that each have holes.
"And when you put layers of Swiss cheese over one another, you block some of those holes," he says. "But none of the layers in and of themselves are perfect. We need to accept that."
So the best bet, he says, is to use as many of those layers as possible — including masks.
This segment aired on June 30, 2020.