How many people should constantly use face masks to end the Covid-19 pandemic?

Always and correctly wearing the mask can greatly reduce the spread of the coronavirus. If we used almost everyone in this way, in theory it could eradicate the epidemic

(photo: Ri Butov via Pixabay) Against the coronavirus, waiting for the vaccine and a cure, the mask helps us fight its spread. Numerous studies have shown the effectiveness of the masks and just as many have shown us the different types and their validity. This was stated by a US research, conducted by Arizona State University and other universities, which returns to the effectiveness of these devices, stating that the pandemic could end if at least 70% of people used the masks systematically when in presence. of other people. The research is the result of a mathematical analysis and photographs what could happen in an ideal scenario, where everyone always and correctly wears the mask. The results, published in Mathematical Biosciences, were today also taken up by another study by the National University of Singapore, published in Physics of Fluids, which returns to the effectiveness of masks and reconfirms data from Arizona State University.

Droplets and particles via aerosol

Among the main transmission routes of the Sars-Cov-2 coronavirus are the droplets of saliva that come into contact with the mucous membranes when the infected person speaks or coughs or even smaller particles dispersed in the air (aerosol) - even if this path of contagion is less frequent - or hand-hand contact and then mucous hand contact, which in fact must be avoided. Several researches have shown that the goggle can substantially decrease the distance traveled by droplets. Transmission via aerosol is also successfully reduced, at least to a certain extent, by the use of masks. There are some limits: a leak can always occur from the edges of the masks, especially if they are not worn correctly, both while inhaling and exhaling.

In general, however, masks are an essential and most effective tool to reduce the infection. Today's studies show that when people always use the mask in public places or in the presence of others, the value of Rt, a central parameter for the analysis of the spread of the infection, drops below 1 and the epidemic can be controlled efficiently.

The weight of the measures

In the study on Mathematical Biosciences, the researchers developed a mathematical model, based on various parameters, which evaluates the impact of the different contagion control strategies in the state of New York and throughout the United States. The measures considered are social distancing, contact tracing, preventive quarantine, isolation and use of masks.

Eradicating the pandemic with masks?

Researchers have analyzed the different types of masks available, from the surgical ones to the more filtering N95 ones up to the cloth ones, which in any case can reduce the spread of the virus.

In an ideal scenario, in which the vast majority of people always wear devices, you may arrive at a resolution of the problem. "The use of highly effective face masks, such as surgical ones that have an estimated efficacy of 70% or greater," the authors write in the publication, "could lead to the eradication of the pandemic if at least 70% of residents of the state of New York constantly used these devices in public (while at national level it is necessary that at least 80% comply) ”with this rule. So much so that the study indicates among the points in focus that "the widespread and sustained use of masks [surgical, ed] could lead to the elimination of Covid-19". Those made of cloth, on the other hand, have an estimated effectiveness of less than 30%, therefore, it being understood that they may have some role in countering the spread of the epidemic, they protect only to a limited extent.

Always according to the conclusions of the study , contact tracing and quarantine, taken individually, have a marginal impact in reducing the load of Covid. Furthermore, of course, combining all the measures together has an even more significant effect against the spread of the virus.