Washington (AFP)

Remdesivir shortens recovery time for Covid-19 patients, according to a study by the United States Institutes of Health, becoming the first drug proven to work against the new coronavirus.

Here is the main part of what we know about it.

- What is remdesivir? -

Remdesivir is an investigational drug produced by the American laboratory Gilead Sciences, which was originally developed to treat patients with Ebola hemorrhagic fever.

It showed promise in trials in 2016, and was then tested in a large study in the Democratic Republic of Congo, which compared it to three other treatments.

This study was completed in 2019 and did not conclude that the drug increased the survival rate as much as that of two other treatments.

In February, the National Institute of Infectious Diseases announced that it would take the remdesivir out of the closet to test it against the SARS-CoV-2 virus, which causes Covid-19 disease, because it had shown promising results. in animals against other coronaviruses, SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome).

- How effective is it? -

The results of this study, on more than a thousand people, were announced Wednesday, with the conclusion that hospitalized patients with Covid-19 and in respiratory distress recovered faster than those receiving a placebo.

More specifically, patients treated with remdesivir recovered 31% faster on average than others.

"Although the results were clearly positive from the point of view of their statistical sense, they were modest," nuanced Thursday on NBC the director of the National Institute of Infectious Diseases, Anthony Fauci, who advises the White House in this context of crisis.

Clearly, even if the drug works, it is not a miracle cure.

But it is however the "demonstration" that a drug can act, and it could therefore open the way to better treatments. As was the case for HIV treatments developed in the 1980s, which were much less effective than those used today.

The results also showed that remdesivir lowered the mortality rate - from 11.7% to 8% - but this data is considered less reliable because it is below the level of statistical relevance.

- Why have there been contrasting results? -

The U.S. study was announced on the same day as another smaller study published in the medical journal The Lancet, which did not find a beneficial outcome with remdesivir.

The study involved 237 patients in Wuhan, China, and was also a randomized controlled trial, considered the highest standard of study. But it was interrupted for lack of sick people because the epidemic stopped in Wuhan.

"The magnitudes of this trial are too small to draw any real conclusions," said Stephen Evans, expert in medical statistics at the London School of Hygiene & Tropical Medicine.

- When will it be available? -

Remdesivir has already been given to patients around the world, both in and outside of clinical trials.

In the United States, the American Medicines Agency (FDA) should soon grant an authorization for emergency use, that is to say before its formal approval.

The head of the agency "is moving very quickly," said Fauci on Thursday, who said he spoke to him on Wednesday evening. "They haven't made a decision yet (...) but I would say we will see that in the reasonably near future."

Because the drug is complicated to produce and administered by injections, questions have been raised about possible initial restrictions.

Gilead Sciences boss Daniel O'Day announced that the laboratory currently has 1.5 million doses, which he has pledged to donate, making it possible to treat 140,000 patients "on the basis of a treatment of 'ten days'.

But according to another study, a five-day treatment would be as effective as ten days.

- How does it work ? -

Remdesivir directly attacks the virus. This is called a "nucleotide analog". It inserts itself into the coronavirus genome and short-circuits it to prevent it from replicating.

"The virus doesn't pay much attention to what it incorporates," says virologist Benjamin Neuman of Texas A&M University. "Viruses generally try to go fast, and exchange speed for prudence".

© 2020 AFP