Can wearing a face mask help 'generate immunity' from COVID-19?

Closeup portrait of a young African American woman with face mask on the studio against white background.
Closeup portrait of a young African American woman with face mask on the studio against white background.

Health experts and organizations, including the Centers for Disease Control and Prevention, have been urging people to wear face masks for months to help slow the spread of the coronavirus. And now a new commentary published in the New England Journal of Medicine theorizes that population-wide face mask use may have additional benefits — namely, by making you less ill if you get COVID-19 and allowing a very small amount of the virus to get through and possibly trigger protective “immunity” against the coronavirus.

It’s worth noting that these are only proposed theories. But “if this hypothesis is borne out, universal masking could become a form of ‘variolation’” — referring to a now obsolete and risky practice in which patients were exposed to a small amount of smallpox scabs containing the variola virus to trigger an immune response — “that would generate immunity and thereby slow the spread of the virus in the United States and elsewhere, as we await a vaccine.”

Experts in the commentary also suggest that the severity of a COVID-19 infection is related to how much of the virus patients are exposed to.

The role face masks play

Dr. Brian Garibaldi, director of the Johns Hopkins Biocontainment Unit and associate professor of medicine at the Johns Hopkins University School of Medicine, tells Yahoo Life that more research is needed to prove these hypotheses. But he calls the theory that mask wearing might allow in very small viral particles that then generate some protective immunity against the coronavirus “an intriguing possibility.”

Face masks help protect people by effectively filtering out the “vast majority” of virus particles, Dr. Dean Winslow, an infectious disease specialist at Stanford Health Care, tells Yahoo Life. But no mask provides 100 percent protection (the coveted N95 masks filter out 95 percent of airborne particles), which means tiny amounts of the virus may still get through.

Dr. Monica Gandhi, co-author of the commentary, theorizes that this minimal exposure to the virus might lead to “asymptomatic or mild infections” — rather than more severe ones if the person hadn’t been wearing a mask — and they might provide “short-term immunity.” (However, scientists still don’t know how long immunity lasts after a coronavirus infection.)

“Masks will significantly cut down the amount of COVID you might come into contact with, but they may not block all of it if you walk into an area where [an infected person] might sneeze,” Garibaldi explains. If you’re wearing a mask in that scenario, “you only get a little bit of exposure and it may not be enough to make you very sick or sick at all, but it might prime your immune system. So if you came into contact with the virus again, you might have an immune response.”

While any exposure to the coronavirus sounds understandably scary, experts explain that it’s not just about exposure to the virus, but also how much (the viral load) and for how long. “There’s good data that the risk of getting infected with SARS-CoV-2 [the virus that causes COVID-19] is the product of the amount of virus that’s in the air times the number of minutes or hours that you’re exposed to it,” explains Winslow.

Gandhi, a professor of medicine and associate division chief of the Division of HIV, Infectious Diseases, and Global Medicine at UCSF/San Francisco General Hospital, says, “Our theory is masks have a major advantage, not only in decreasing transmission but also possibly decreasing the severity of illness.”

However, some experts are skeptical about the theories without more research. “It seems like a leap,” Saskia Popescu, PhD, an infectious disease epidemiologist at the University of Arizona (who was not involved in the commentary), told the New York Times. “We don’t have a lot to support it.”

Popescu added that in addition to wearing masks, “we still want people to follow all the other prevention strategies,” such as social distancing and washing hands with soap and water for 20 seconds (or using hand sanitizer).

Other experts expressed concerns that people might incorrectly misinterpret the hypothesis to mean that masks aren’t effective. As Gandhi states: “There are so many advantages of facial masking, and even though we know it’s a hard thing to swallow for the American population, it really seems to have so many different [ways] that it helps.”

Masks as the ‘best defense’

Gandhi says when the CDC first issued guidelines to the public on wearing masks, it “kind of got the messaging wrong” by focusing on the fact that “masks protect others.” “They’re right that it protects others,” she says, “but that message didn’t really work. It would have helped if we said [earlier on] that masks protect you and others. It really protects you from transmission.”

The CDC’s guidelines on masks have evolved as the scientific community has learned more about the coronavirus. Most recently, while giving testimony before a Senate subcommittee hearing on Sept. 16, CDC Director Dr. Robert Redfield called face masks the “best defense” we have against COVID-19, as reported by CBS News. Redfield also mentioned that face masks may be even more effective than a vaccine, which is not projected to become available until mid-2021.

“I might even go so far as to say that this face mask is more guaranteed to protect me against COVID than when I take a COVID vaccine, because [the vaccine] may be 70 percent” effective, Redfield said. “And if I don’t get an immune response, the vaccine is not going to protect me. This face mask will.”

But Gandhi notes that wearing masks is just an “intermediate step to get to that vaccine.” In the meantime, she says, the multiple benefits of wearing one make her feel “hopeful.”

“This has been a really scary time because there’s this feeling that there’s no control, and it gives me a lot of hope and optimism that something very simple like wearing facial masks ... can provide us some control over it. There is something we can do.”

Garibaldi agrees, telling Yahoo Life: “We should wear a mask because that’s the only way we’re going to get transmission under better control until there’s a vaccine. The most important reason to wear a mask is it’s going to save lives. If we all masked up right now and stopped the nonsense of masks as a political statement, we would save hundreds of thousands of lives over the next six months.”

As Gandhi notes, COVID-19 is a “deadly disease for some,” adding, “Anything we can do to both decrease people getting it and decrease the severity of illness, that’s a win-win.”

For the latest coronavirus news and updates, follow along at According to experts, people over 60 and those who are immunocompromised continue to be the most at risk. If you have questions, please reference the CDC’s and WHO’s resource guides.

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