Paris (AFP)

On the one hand, dozens of drugs tested. On the other, a hundred vaccines in the pipeline. Whether it's treating Covid-19 or preventing it, research abounds and advances quickly, even if we are still awaiting the discovery that will change the course of the disease.

TREATMENTS: HOPE, EXPECTATIONS

- Dexamethasone: avoiding deaths

Inexpensive and readily available, this steroid is at this stage the only drug that appears to improve survival in Covid-19 patients.

However, this only concerns the most seriously affected patients: those who are placed on artificial ventilation and, to a lesser extent, those to whom oxygen is administered without intubating them.

In the former, dexamethasone reduces mortality by a third, according to initial results from the large British clinical trial Recovery.

Announced on Monday, the results have yet to be published in a scientific journal. But in the process, the British government announced that this treatment would be immediately used to treat the affected patients.

Dexamethasone is already used in many indications for its powerful anti-inflammatory and immunosuppressive effects.

- Remdesivir: modest efficacy

This antiviral drug is promoted by the United States, which officially announced at the end of April that it reduces the recovery time for patients.

The publication of this research in late May in the New England Journal of Medicine confirmed these claims.

However, the effectiveness of remdesivir is not spectacular: it reduces the recovery time for hospital patients from 15 to 11 days on average and has not proven benefits in terms of reducing mortality.

The emergency use of remdesivir in hospitals has been authorized by the United States, then Japan. Europe is currently studying an application for marketing authorization.

Manufactured by the Gilead laboratory, remdesivir was originally developed - in vain - against Ebola hemorrhagic fever.

- Hydroxychloroquine: the Scottish shower

Boasted by US President Donald Trump and the controversial French researcher Didier Raoult, this treatment did not confirm the hopes placed in him, on the contrary.

In early June, the UK clinical trial Recovery concluded that hydroxychloroquine had no beneficial effect against Covid-19.

This finding led the American health authorities on Monday to withdraw the authorization to use emergency hydroxychloroquine against Covid-19 (as well as a closely related drug, chloroquine).

Then on Wednesday, the WHO (World Health Organization) announced that it was stopping clinical trials on hydroxychloroquine as a treatment for Covid-19.

Used according to countries as a treatment for malaria or autoimmune diseases, this drug has been at the center of a long saga with very political aspects since the beginning of the pandemic.

A saga marked by an academic scandal: in early June, the prestigious review The Lancet had to withdraw a critical study on hydroxychloroquine, marred by strong suspicions of fraud.

This scandal has confirmed the opinion of the fierce supporters who keep this drug despite the evidence that accumulates.

- A full pharmacy

In addition to the three drugs mentioned above, many others are under evaluation. In total, more than a thousand clinical trials cover dozens of treatments around the world, according to the Lancet database (https://covid-trials.org/).

Among the main potential treatments, the combination of two anti-HIV drugs, lopinavir and ritonavir (alone or in combination with other antivirals), transfusion to patients of the blood plasma of recovered people, chlorpromazine (an antipsychotic) or tocilizumab (which could fight against the inflammatory phenomenon responsible for the most serious cases).

But despite the announcement effects in a very competitive race, none of these tracks has so far proved conclusive.

Especially since it seems illusory to believe in a miracle product against Covid-19: most specialists think that the key will not be a single molecule but a combination of several drugs from different families, in order to add their effects.

VACCINES: THE ACCELERATED RACE

- How many vaccines?

In its last point, as of June 16, the WHO counted 11 clinical trials in progress for as many vaccine candidates around the world.

Almost half of these human trials are in China (5). This country, which has seen the emergence of the SARS-CoV-2 virus and which fears a resumption of the epidemic in Beijing, wants to be the first to have a vaccine and does not hesitate to authorize accelerated procedures.

The clinical trials in progress in the world for "vaccine candidates" are called "phase 1", that is to say they aim above all to assess the safety of the product, or else "phase 2", that is they are already evaluating their effectiveness.

Only partial results, some described as "encouraging", have been published so far.

Among the most advanced projects, we can cite the European one, from the University of Oxford in cooperation with AstraZeneca, and the Chinese project from the Military Academy of Medical Sciences and the pharmaceutical company CanSinoBIO.

In addition to the trials already started, the WHO counts 128 vaccine candidate projects which are in the pre-clinical phase of development.

Another count made by the British School of Medicine, London School of Hygiene & Tropical Medicine counts no less than 194 anti-Covid vaccine projects, including 17 in the clinical trial stage.

- Different approaches

WHO classifies the hundreds of ongoing projects in eight different categories corresponding to types of proven or, conversely, experimental vaccines.

These are the classic "live attenuated" or "inactivated" type vaccines, so-called "subunit" vaccines based on proteins (presenting an antigen to the immune system, without viral particles).

These are also so-called "viral vector" vaccine projects, which use advanced techniques to manufacture viruses whose sole purpose is to elicit an immune response in humans.

Among the projects are also "DNA" or "RNA" vaccines which are experimental products using pieces of modified genetic material.

- Date, key question

The European Medicines Agency (EMA) estimated in mid-May that a vaccine could be ready within a year in an "optimistic" scenario.

But the most optimistic are squarely betting on the end of this year to counter a possible second wave of the pandemic which could hit the northern hemisphere next winter.

As part of its "Warp Speed" operation, the US government hopes to deliver 300 million doses of vaccine by January 2021 (almost the equivalent of the American population), via funding and support for laboratories.

In China, the state-owned pharmaceutical company Sinopharm, which is currently preparing two vaccine candidates, hopes to market it in late 2020-early 2021.

In Europe, where several projects are also underway, it is also hoped that a vaccine will be successfully developed by the end of this year.

Germany, France, Italy and the Netherlands have also signed an agreement with the pharmaceutical group AstraZeneca to guarantee the supply to the EU of 300 million doses of a possible vaccine.

- At what price ?

Pharmaceutical groups have repeatedly raised the fact that they plan to make their vaccine available at reasonable prices, or even at cost.

AstraZeneca is committed to "not making profits on this vaccine", according to its president for France, Olivier Nataf, with a price of around 2 euros per dose.

- Who will be vaccinated?

The United States has announced its intention to give priority, in future vaccination campaigns, to the elderly, citizens with a medical history and so-called essential workers.

According to the US government, however, it will also depend on the results of clinical trials.

© 2020 AFP