Faced with a virus as contagious as the current coronavirus, the mask remains the best way to reduce the number of viral particles absorbed to allow immunity to neutralize the infection.
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The race for drugs against COVID-19 must not make us forget that prevention is an essential aspect in our fight against this disease. In addition to basic hygiene measures such as washing your hands regularly, it is increasingly clear that wearing a mask can play a very important role in reducing the transmission of the virus and preventing an exponential increase in the number of people infected. .
The coronavirus is spread primarily through droplets secreted by an infected person, whether symptomatic or not. These particles, which are quite large, fall quickly to the ground and generally do not cross a distance of more than 2 meters (hence the recommendation to maintain this distance between people).
On the other hand, several observations made since the start of the pandemic suggest that the virus can also spread in the form of much smaller particles: these aerosols are lighter, remain suspended in the air for a longer time and can therefore spread over long distances in a closed room (similar to a puff of a cigarette).
Wearing a mask therefore remains the only way to reduce the entry of these viral particles in suspension in the nose and mouth.(1).
The primary function of the mask is to act as a physical barrier that prevents the vast majority of viral particles from being expelled (in the case of infected people) or being picked up by people present nearby.
An interesting point, often overlooked, is that the mask does not have to be 100% effective to have a positive role: several studies indicate that the severity of respiratory viruses, like that of COVID-19, is in general proportional to the amount of virus (inoculum) absorbed during infection(2).
When present in too many numbers, the virus overloads our immune system and causes uncontrolled inflammation that compromises the function of several vital organs. By reducing the number of viral particles that enter the body, the mask therefore allows the immune system to neutralize the virus more effectively, reduce the viral load and prevent the disease from progressing to more advanced stages.(3).
Data obtained with animal models infected with the SARS-CoV-2 coronavirus strongly suggest that this reduction in the number of viruses may indeed reduce the severity of COVID-19.
For example, one study showed that models infected with a high dose of virus were sicker than those given a small amount of virus particles.(4).
Another study observed that those who wore a mask were less likely to develop COVID-19 or, when infected, had much less severe forms of the disease.(5).
According to a recent commentary in the famous New England Journal of Medicine(2), this protective effect of the mask is analogous to variolation. Before the discovery of a smallpox vaccine, a very small amount of the virus was inoculated into healthy people to create a mild infection that boosted their immunity and allowed them to become resistant to the virus.
The authors propose to consider the mask as a form of variolation, a way of exposing the body to a minimum of viral particles in order to allow the immunity to develop a response that will neutralize the virus and prevent the disease from progressing. to severe forms which put the life of the infected person in danger, because of an excessively high viral load.
In other words, the mask does not completely prevent the transmission of the virus, but those infected remain asymptomatic or develop milder forms of COVID-19.
This damage reduction is extremely important, not only because it saves many lives, but also because it decreases the risk of the health system crippling and becoming unable to adequately care for those affected by others. serious illnesses (surgeries, cancer treatments).
It is mentioned more and more often that we must learn to adapt to the presence of the coronavirus if we want to return to a more or less normal life.
By limiting the damage caused by the virus, the mask is an essential tool for this adaptation, until the rate of transmission of the virus can be significantly reduced with the help of an effective, safe vaccine administered to large segments of the population. population.
(1)van der Sande M et al. Professional and home-made face masks reduce exposure to respiratory infections among the general population. PLoS One 2008; 3 (7): e2618.
(2)Gandhi M and GW Rutherford. Facial masking for Covid-19: potential for “variolation” as we await a vaccine. N. Engl. J. Med., published on September 8, 2020.
(3)Gandhi M, Beyrer C, Goosby E. Masks do more than protect others during COVID-19: reducing the inoculum of SARS-CoV-2 to protect the wearer. J Gen Intern Med 2020 July 31 (Epub ahead of print).
(4)Imai M et al. Syrian hamsters as a small animal model for SARS-CoV-2 infection and countermeasure development. Proc. Natl Acad. Sci. USA 2020; 117: 16 587-16 595.
(5)Chan JFK et al. Surgical mask partition reduces the risk of non-contact transmission in a golden Syrian hamster model for Coronavirus Disease 2019 (COVID-19). Clin. Infect. Say., published on May 30, 2020.