What is remdesivir, this new drug against Covid-19?

Text by: Nicolas Rocca Follow

After hydroxychloroquine and tocilizumab, it is now remdesivir that would be an effective remedy against the virus. A study presented briefly by Anthony Fauci, an immunologist who manages President Trump's crisis cell, would show the positive results of this antiviral already used against Ebola. These injections would considerably reduce the healing time. RFI asked three questions about this molecule to Professor Gilles Pialoux, head of the infectious diseases department at the Tenon hospital in Paris.

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RFI: Professor Pialoux, can you present what is remdesivir and explain how it works ?

Gilles Pialoux: First of all, it should be noted that with the Covid-19, we are faced with a complex disease, which has several facets. To simplify, at the beginning it is a disease which is essentially viral. In benign forms, for example, the virus acts. Then, when we observe more serious forms, it is no longer SARS CoV2 (the Covid-19 virus) which dominates the picture, but the immune response which is too important and this creates what is called a cytokine storm. The respiratory system and other organs are inundated with the immune response. It is like a gum which by dint of rubbing would make a hole in the paper, the immune reaction becomes too strong for the body to support.

Remdesivir attacks viral infection, therefore rather in moderate forms. It acts in a fairly conventional manner for an antiviral, that is to say that it blocks the replication, the multiplication of the virus. Remdesivir has already shown its effectiveness in the laboratory against Ebola and other coronaviruses.

RFI: What is the difference with other treatments that have been publicized?

If you take the tocilizumab that we talked about recently for example, it's completely different. It is an antibody that targets a specific inflammation protein. It prevents the overactivity of the immune system responsible for some of the serious forms of Covid 19. On this subject we had a very pragmatic trial which showed results, we are testing 60 patients with the product and others without and we sees when the results come out. There is an efficacy on moderate and severe forms, but we do not yet have data for resuscitation. These results were obtained very quickly. We started on March 30 and the results arrived on April 25, it's rarely that fast.

For the hydroxycholoroquine which has been very publicized also it is very complicated. Because there would be an antiviral, but also an anti-inflammatory effect; it is not yet known which of the two aspects would work. Those who promote it play on both fields. In reality, we still have no controlled trials that demonstrate its effectiveness.

RFI: What do you think of the American study? Is the recovery time reduced by 31% significant?

Anthony Fauci says there are arguments to claim that the virus can be blocked. It is not just anyone, it is someone serious so it is still quite strong. But you have to take it all with tweezers, be cautious and humble about the results. The question of shortening the healing time is very important, and above all what is its weight in clinical reality? This is useful because the shorter the illness, the less the virus circulates, clearly the less the virus is present the less the patient will be contagious. Then you have to see if it affects mortality. For the moment, this is not significant and there is a lack of data. It must be remembered that we discuss on press releases, usually it is on scientific data, but the research is so visible worldwide that we rush to publish.

The results are mixed. As for American studies, healing time is reduced but mortality is not reduced. Another study, Chinese, on a smaller number of patients, has negative results.

For now, we are mainly waiting for Discovery, the European clinical trial, where 5 treatments are being tested, which will allow us to compare their effectiveness with each other. But beware, you have to understand that we are not in the competition between antiviral treatments and those that act on the immune system. They can very well be complementary.

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