Face masks could be inadvertently giving wearers immunity from coronavirus by acting as a type of crude ‘vaccine’, experts have suggested.
The researchers behind the theory say wearing a face mask could make people less sick, or asymptomatic, because the coverings reduce the infectious dose they are exposed to.
If the theory is proven, masks could become a universal form of inoculation that would generate immunity, according to experts.
Repeated exposure to small amounts of Covid-19 may train the body to recognise the disease and fight it off, effectively immunising them.
However, the theory detailed by scientists from the University of California, will unlikely be proven beyond a reasonable doubt because it would require exposing people with and without masks to the virus in clinical trials, a breach of ethics.
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The theory was published in the New England Journal of Medicine.
The experts stressed that it is just a theory and warned mask wearers not to become complacent or try to catch the virus in the hopes that it would build immunity.
Dr Monica Gandhi, an infectious disease physician, wrote in the paper: “You can have this virus but be asymptomatic.
“So if you can drive up rates of asymptomatic infection with masks, maybe that becomes a way to variolate the population.”
She told the Sunday Telegraph: “To test the variolation hypothesis, we will need more studies comparing the strength and durability of SARS-CoV-2–specific T-cell immunity between people with asymptomatic infection and those with symptomatic infection, as well as a demonstration of the natural slowing of SARS-CoV-2 spread in areas with a high proportion of asymptomatic infections.
“However, it is true that the proportion of asymptomatic infection being increased by masking might increase the proportion of the population who achieve at least short-term immunity to the virus while we await a vaccine.”
Critics worry the theory could result in complacency or unnecessary risks.
Saskia Popescu, an infectious disease epidemiologist based in Arizona who was not involved in the research, told the New York Times: “It seems like a leap. We don’t have a lot to support it.
“We still want people to follow all the other prevention strategies.
“That means staying vigilant about avoiding crowds, physical distancing and hand hygiene – behaviors that overlap in their effects, but can’t replace one another.”
Today the UK recorded almost another 3,500 cases of the deadly virus as officials grapple with an accelerating R-rate.