Paris (AFP)

The toll of the Covid-19 epidemic could further double in the United States by the end of February, to exceed 500,000 deaths, but wearing a mask could prevent 130,000 of these deaths, conclude projections published on Friday.

According to the scenario considered most plausible by these researchers, where local governments would again restrict social interactions and economic life above a certain mortality threshold, the United States would still deplore 511,000 deaths from the Covid-19 end. February.

However, if 95% of the population of each state systematically wore a protective mask in the presence of other people, that toll could be reduced by almost 130,000 people, according to forecasters from the Institute for Health Metrics and Evaluation (IHME).

Even if the mask was only 85% respected, 95,000 lives could be saved, they add in their article, published in the journal Nature Medicine.

"It is becoming increasingly clear that masks considerably reduce the transmission of respiratory viruses such as SARS-CoV-2, and therefore limit the spread of Covid-19", stress the authors.

In September, about 50% of people in the United States said they used a protective mask, despite some politicians' reservations about their effectiveness.

Donald Trump has rarely worn a mask in public, he scoffed at the reverse habit taken by his presidential rival Joe Biden, and few of his supporters cover their faces during his rallies.

Since January, the new coronavirus has infected at least 8.3 million people in the United States and killed at least 223,000 of them.

In mid-July, the IHME modeling teams had seen it right by predicting 224,000 deaths on November 1.

On the threshold of winter, the country is experiencing an upsurge in the epidemic, with 75,000 new cases detected on Thursday, almost double the levels recorded a month ago.

While most experts agree that an effective vaccine is unlikely to be available for several months, non-pharmacological measures such as wearing masks, physical distancing, isolating patients and tracing contacts are, by default, the most effective tools to contain the epidemic.

- "Reference scenario" -

To predict what the next few months might look like, epidemiologists and forecasters at IHME constructed three possible scenarios.

In the first, deemed unlikely, states continue to gradually lift current restrictions on travel and social interactions.

As of February 28, the total death toll from Covid-19 would then exceed 1 million and at least 152 million people (45% of the population) would have been infected with the coronavirus, they estimate.

But it is more realistic to expect that states instead reinstate the measures taken during the first wave of the epidemic, such as closing schools, restricting the size of public gatherings and totally or partially closing businesses deemed non-essential.

The study, which qualifies this hypothesis as a "reference scenario", shows that in the past, this type of measure was often taken when the level of mortality in a city or a state exceeded the threshold of 8 deaths per year. million inhabitants every day.

45 of the 50 states in the United States will have exceeded this threshold before the end of February, she believes.

Even with the reactivation of these restrictions, the total toll of the epidemic would reach 511,000 dead and nearly 72 million infections by the end of February, the article adds.

Finally, in a third scenario, where 95% of the adult population would adopt the mask, “129,574 lives could be saved” over the period from September 22 to February 28, he concludes.

© 2020 AFP