Its widespread use appears to limit the amount of virus particles that are emitted and reduce the severity of the disease, according to one hypothesis.
Since March, the chinstraps have been incorporated into our daily routine. Its use in the general population can serve as a means of controlling the source of infection by reducing the spread in the community, since it limits the respiratory droplet excretion of infected individuals who have not yet developed symptoms or who remain asymptomatic.
Of course, the use should be considered only “as a complementary measure and never as a replacement for the preventive measures of physical distancing, hand hygiene, respiratory etiquette and avoiding touching the face, nose, eyes and mouth “, they affirm from the Ministry of Health.
This week, the magazine The New England Journal of Medicine published a new analysis by Monica Gandhi and George W. Rutherford with an attractive hypothesis: the use of masks on a global scale could be creating immunity against coronavirus infection. In addition, it could make the infections milder and have a higher proportion of asymptomatic.
For Gandhi and Rutherford, both from the University of California in San Francisco (USCF, in the USA), “this possibility is consistent with a theory about viral pathogenesis, which holds that the severity of the disease is proportional to the viral inoculum received“That is, the amount of virus particles that caused the infection. In SARS-CoV-2 infections, high doses of viral inoculum can hit the immune defenses, increasing the severity of the disease.
“If the viral inoculum is important in determining the severity of the SARS-CoV-2 infection, one reason to wear face masks would be reduce load to which the carrier is exposed and the consequent clinical impact of the disease “, they expose.
For the authors, since the masks can filter some droplets that contain viruses, their use could reducing the dose an exposed person inhales: “If this theory is reaffirmed, use in the entire population could contribute to increasing the proportion of asymptomatic infections.”
The Gandhi and Rutherford hypothesis is related to the concept of variolization, which was the method used – before Edward Jenner invented the vaccine – to immunize against smallpox with material taken from a patient in the hope that it would later occur. a mild but “protective” infection.
If confirmed, the worldwide use of masks could become a form of variolization that would generate some immunity and slow the spread of the virus while waiting for a vaccine. Of course, Gandhi and Rutherford want to make it clear that, for the moment, it’s just a hypothesis.
“We would need more studies to compare the rate of asymptomatic infection in areas with and without the use of a general mask, but we cannot force this investigation as it would be unethical. We can only collect observations that support the theory,” they explain to SINC.
Various virological and epidemiological evidence supports that masks can reduce the severity of the disease and increase the proportion of asymptomatic infection. The need for chinstraps became apparent when reports began to appear describing the high rates of spread of SARS-CoV-2 through the nose and mouth of presymptomatic or asymptomatic patients, spread rates equivalent to those of humans. with symptoms.
Previous studies related to other respiratory viruses reveal that the use of masks can also protect those who have the infection, by preventing viral particles from entering the nose and mouth. “As SARS-CoV-2 continues to spread, it is possible that one of the pillars of the fight against the covid-19 pandemic – the use of masks – could help reduce the severity of the disease and ensure that a a higher proportion of new infections are asymptomatic, “the authors argue.
Likewise, in an outbreak in March on an Argentine cruise ship – in which passengers were provided with surgical masks and N95 masks to staff – the asymptomatic infection rate was 81% (compared to just 20% of previous outbreaks on cruise ships where the importance of chinstraps was not yet known).
In addition, last July another research was published, in which Gandhi also participated, indicating how the use of these masks can reduce the severity of the disease among people who become infected: “Asymptomatic infections can be detrimental to the spread, but they could actually be beneficial if they lead to higher exposure rates“.
“And exposing society to SARS-CoV-2 – but without the unacceptable consequences of serious illness – with protective masks could lead to increased immunity at the community level and slower spread while waiting for a vaccine “, the researchers of the previous work said then.
Despite concerns regarding safety, global distribution, and absorption, there are high hopes that an effective vaccine against SARS-CoV-2 will be produced. However, hope for immunization is not limited to preventing infections: most trials include a secondary outcome of decreased severity, as the increase in cases in which the disease is mild or asymptomatic it would also be a victory for public health.
Last August, another study showed promising data suggesting that even after mild or asymptomatic covid-19 there is a strong cellular immunity, so any strategy that can reduce the severity of the disease should also increase the immunity of the entire population.