Use of masks could reduce severity of COVID-19, study finds

It is proven that the correct use of masks prevents the contagion and spread of the coronavirus. But now several researchers suggest that it could help reduce the severity of the disease and ensure that a higher proportion of new infections are asymptomatic.

According to a recent study published in the journal The New England Journal of Medicine, if this hypothesis is confirmed, “universal masking” could become a form of “variolation” that would generate immunity and therefore it would slow down the spread of the virus while waiting for a vaccine.

Variolation was a process in which people susceptible to smallpox were inoculated with material extracted from a gallbladder of an infected person, with the intention of causing a mild infection and consequent immunity. This procedure was practiced only until the introduction of the vaccine that finally eradicated smallpox.

High virus inoculation implies more severity

According to the study, conducted by scientists at the University of California, recent virological, epidemiological, and ecological data suggest that facial masking can also reduce the severity of the disease among infected people.

This possibility is consistent with a long-standing theory of viral pathogenesis, which holds that the severity of the disease is proportional to the viral inoculum received.

“In viral infections in which host immune responses play a predominant role in viral pathogenesis, such as SARS-CoV-2, high doses of viral inoculum can overwhelm and deregulate innate defenses, increasing disease severity. ”, Highlights the study.

If the viral inoculum is important in determining the severity of the COVID-19, a further hypothetical reason to wear face masks would be to reduce the dose of virus the wearer is exposed to and the subsequent clinical impact of the disease.

“Since masks can filter some virus-containing droplets (with the filtering capacity determined by the type of mask), the mask could reduce the inoculum that an exposed person inhales,” says the study.

If this theory is confirmed, population masking could contribute to increasing the proportion of COVID-19 infections that are asymptomatic.

The Centers for Disease Control and Prevention (CDC) estimated that the typical asymptomatic infection rate was 40% in mid-July, but asymptomatic infection rates have been reported to be higher than 80% in settings with universal facial masking. , which provides observational evidence for this hypothesis.

Countries that use masks are doing better

They note that countries that have embraced whole population masking have fared better in terms of rates of serious COVID-related illness and death, “which, in settings with limited evidence, suggests a shift from symptomatic to asymptomatic infections.” .

The most obvious way to prevent society from suffering the devastating effects of COVID-19 is to promote measures to reduce both the transmission and the severity of the disease. “But SARS-CoV-2 is highly communicable, it cannot be contained by syndromic-based surveillance alone, and it is proving difficult to eradicate, even in regions that implemented strict initial control measures,” say the researchers.

Promising data has emerged in recent weeks suggesting that strong cell-mediated immunity is the result of even mild or asymptomatic SARS-CoV-2 infection, so any public health strategy that can reduce the severity of the disease it should also boost the immunity of the entire population.

But to “test our hypothesis that masking the entire population is one of those strategies, we need more studies comparing the rate of asymptomatic infection in areas with and without universal masking.”

An alternative while the vaccine arrives

Despite concerns regarding safety, global distribution, and eventual acceptance, the world has high hopes for a highly effective coronavirus vaccine, and as of early September, 34 candidate vaccines were under clinical evaluation and hundreds more in the process. developing.

However, while we await the results of vaccine trials, any public health measure that can increase the proportion of asymptomatic infections can make the infection less deadly and increase the immunity of the entire population without serious illness or death.

“Ultimately, fighting the pandemic will mean reducing both transmission rates and the severity of the disease. Growing evidence suggests that population-wide facial masking could benefit both components of the response, ”they conclude.

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