New theory: Could masks help crudely immunise people?
A wearer is exposed to just enough of the virus to spark a protective immune response
As the world awaits a safe and effective coronavirus vaccine, a team of researchers has come forward with a provocative new theory: that masks might help to crudely immunise some people against the virus.
The unproven idea, described in a commentary published last week in The New England Journal of Medicine, is inspired by the age-old concept of variolation, the deliberate exposure to a pathogen to generate a protective immune response. First tried against smallpox, the risky practice eventually fell out of favour, but paved the way for the rise of modern vaccines.
Reduce the risk
Masked exposures are no substitute for a bona fide vaccine. But data from animals infected with the coronavirus, as well as insights gleaned from other diseases, suggest that masks, by cutting down on the number of viruses that encounter a person’s airway, may reduce the wearer’s chances of getting sick. And if a small number of pathogens still slip through, the researchers argue, these might prompt the body to produce immune cells that can remember the virus and stick around to fight it off again. “You can have this virus but be asymptomatic,” said Dr. Monica Gandhi, an infectious disease physician at the University of California, San Francisco, and one of the commentary’s authors. “So if you can drive up rates of asymptomatic infection with masks, maybe that becomes a way to variolate the population.”
That does not mean people should don a mask to intentionally inoculate themselves with the virus. “This is not the recommendation at all,” Gandhi said. “Neither are pox parties,” she added, referring to social gatherings that mingle the healthy and the sick.
The theory cannot be directly proven without clinical trials that compare the outcomes of people who are masked in the presence of the coronavirus with those who are unmasked — an unethical experimental set-up. And while outside experts were intrigued by the theory, they were reluctant to embrace it without more data, and advised careful interpretation.