Study: Masks Crucial to Preventing Second Wave of Covid-19 Pandemic

RIO DE JANEIRO, BRAZIL – A simulation involving 60 million people shows that if everyone wore a mask most of the time, there would be no second or third waves of the coronavirus pandemic. Even in much lower percentages, the spread of Covid-19 would see its reproduction rate (basic reproduction number or R0) drop without the need for more extreme containment measures.

According to the study’s authors, in the absence of more technological and advanced tools, if the mass population would cover their face this would allow the time needed to find a vaccine. However, there are still skeptical scientists.

Common sense says that wearing a mask protects you against any airborne particles or pathogens. But for science this is not as clear. Until the current pandemic emerged, there were few studies on the effectiveness of covering one’s mouth and nose to prevent the spread of viruses. The most recent research is related to the flu or the 2003 SARS outbreak. Perhaps this is why the World Health Organization (W.H.O.) and many governments, such as Spain, have taken so long to recommend or compel its use.

Now, several mathematical models developed by British researchers show that something as unsophisticated as multiple layers of cotton fabric may be the first line of defense against the coronavirus. Its simulation, performed in the UK population, feeds on real data of people infected and on a rate of contagion prior to wearing masks, similar to the maximum reached by a dozen European countries.

With these and other epidemiological parameters, they try to answer the following question: how widespread would mask use need be to lower the R0 to less than one? Lowering it to this figure implies the extinction of the epidemic over a period of time.

“Our tests support the immediate and universal adoption of masks,” says the study’s lead author, Richard Stutt. To date, this Cambridge University researcher has devised models for the spread of diseases among vegetable crops, a knowledge he has applied to the current human pandemic. “If we couple the widespread use of masks with physical distancing and some degree of confinement, the pandemic can be responsibly managed while the economy rebounds, long before there is an effective vaccine,” he adds.

The study’s findings, published in the scientific journal Proceedings of the Royal Society, show that if at least half the population wore masks in public, the rate of infection would fall below R0 = 1. As demonstrated, the pandemic curve will not decline until this limit is reached. With an increasing proportion of people covering their faces, the model suggests that this R0 would move ever closer to zero.

According to this study, in the optimal scenario with the whole population wearing masks, R0 would remain well below 0.5. More importantly, a second or third wave would be prevented if masks were to be complemented with occasional and partial confinements for at least 18 months, a period that is believed to be sufficient to secure a vaccine. The trouble is that these scenarios are a simulation based on a variety of assumptions, as the authors concede.

“Conducting scientific studies to directly quantify the effectiveness of masks is very complicated,” Stutt recalls. “We can see the reduction of a person’s exhaled material with or without a mask, but the most difficult thing is to estimate the impact this has on those susceptible to contagion,” he explains. To accurately determine this, volunteers would need to be deliberately exposed to the pathogen, something that raises several ethical dilemmas.

Ellen Brooks, a public health researcher at the University of Bristol, says, “While masks can reduce transmission in some settings, such as shops or public transportation, they are unlikely to prevent transmission between close and permanent social contacts, such as at home”. Professor Keith Neal, an epidemiologist at the University of Nottingham, accepts the logic that a more widespread wearing of masks will have a greater impact on preventing the spread of the disease, but this “very much depends on the effectiveness of those who will wear them.”

A further concern of some scientists is that the widespread use of masks would create an apparent sense of safety. “There is no evidence that wearing a mask will lead to relaxing other measures,” says Trish Greenhalgh, a professor of basic health care at Oxford University. In her view, the study supports the idea that “the benefits of covering one’s face to reduce infection among the population outweigh the potential harm of its incorrect use.”

So why haven’t the W.H.O. and most Western governments recommended (or forced) the use of face masks to date? Juan Jesús Carrero, professor of epidemiology at the Karolinska Institute in Stockholm, Sweden, points out that this may be due to a build-up of circumstances caused by a pandemic unseen in recent times.

“The first [reason] is to construe the absence of scientific studies as lack of effectiveness,” explains Carrero. Initially, authorities placed the principle of prevention first. Another was the concern about shortages that would deprive health workers and infected patients of their masks. “The third is that by wearing masks, people relax other measures as or more important, such as physical distancing and hygiene,” says the Spanish scientist.

A fourth concern is that recommending them may not be enough, one needs to know how to wear them. “Its misuse (the way to place them and remove them) can also lead to contagion”. And there’s a fifth concern, recalls Carrero: “Some [including Trump] may not want to wear masks for aesthetic reasons or for feeling suffocated.”

Source: El País

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