Wearing a mask works like a vaccine against COVID-19

Hyderabad: Wearing of mask could actually, in a way, be inoculating people and working like a vaccine against the SARS-CoV-2 virus that causes Covid-19. This is according to a yet-to-be-tested theory published in The New England Journal of Medicine in the form of a letter.

The theory proposed that face masking could be a medium to generate immunity among the population until a vaccine is finalised. The supposition is that it is possible that despite wearing a mask, people when in proximity of others who are carrying the virus and shedding it, can inhale some of the virus particles.

Those who wear masks would be inhaling far fewer virus particles whose number would not be enough to set off a serious or visible infection with symptoms. It is possible that such persons would be asymptomatic or have very mild symptoms.

In a letter to the journal, published on October 29, authors Dr Monica Gandhi and Dr George W. Rutherdord have suggested that universal masking is effective in reducing the rate of new infections by increasing the proportion of asymptomatic infected people, hence reducing the fatality rate.

“If the viral inoculum matters in determining the severity of SARS-CoV-2 infection, an additional hypothesised reason for wearing facial masks would be to reduce the viral inoculum to which the wearer is exposed and the subsequent clinical impact of the disease,” they said in the letter.

If this theory bears out, population-wide masking, with any type of mask that increases acceptability and adherence, might contribute to increasing the proportion of SARS-CoV-2 infections that are asymptomatic, they said.

They also said that countries that have adopted population-wide masking have fared better in terms of rates of severe Covid-related illnesses and death, which, in environments with limited testing, suggests a shift from symptomatic to asymptomatic infections. Any public health strategy that could reduce the severity of disease should increase population-wide immunity as well, should not be ignored.

The authors, however, cautioned that the hypothesis they put forward requires further studies comparing the rate of asymptomatic infection in areas with and without universal masking.

To test the ‘variolation’ hypothesis, 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 the virus spread in areas with a high proportion of asymptomatic infections, are required they said.

Explaining variolation, they said this was the “process whereby people who were susceptible to smallpox were inoculated with material taken from a vesicle of a person with smallpox, with the intent of causing a mild infection and subsequent immunity. Variolation was practiced only until the introduction of the variola vaccine, which ultimately eradicated smallpox.”

Ultimately, combating the pandemic will involve driving down both transmission rates and severity of disease. Increasing evidence suggests that population-wide facial masking might benefit both components of the response, the authors, from the Centre for AIDS Research, Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine (M.G.), and the Division of Infectious Disease and Global Epidemiology, Department of Epidemiology and Biostatistics (G.W.R.), University of California, said.