Paris (AFP)
The vaccination of several billion people in one year has eclipsed the search for treatments against Covid-19: unlike the first, the second is progressing step by step, but several new avenues are a source of hope.
THOSE WHO WALK
- Corticosteroids: this is the first treatment to have been officially recommended by the WHO (World Health Organization), in September 2020, only for the most seriously ill patients.
Based on all available clinical trial data, the WHO recommends “the routine administration of corticosteroids” to patients with “a severe or critical form” of Covid.
In these patients, this treatment reduces mortality and also probably the risk of being placed on life support, according to the WHO.
It makes it possible to fight the inflammation characteristic of severe forms.
- Tocilizumab and sarilumab: these drugs are synthetic antibodies, called "monoclonal", which belong to a family called "interleukin 6 antagonists" (or anti-IL-6).
They have been recommended since July 2021 by the WHO, again for the most serious patients.
The body recommends that these patients "receive both corticosteroids and anti-IL-6".
Initially developed to treat rheumatoid arthritis, an inflammatory disease, tocilizumab (sold under the name Actemra or RoActemra by the Roche laboratory) and sarilumab (sold under the name Kevzara by Sanofi) are immunosuppressants.
Like corticosteroids, they fight the runaway immune system that seems to be the source of severe forms of Covid.
- Ronapreve: this combination of two monoclonal antibodies (casirivimab and imdevimab) was recommended by the WHO on Friday, but only for two types of patients.
First, those "with non-severe forms of Covid who are at high risk of hospitalization", such as the elderly or with a weakened immune system (by cancer or after a transplant, for example).
The medicine cabinet is gradually filling up with anti-Covid treatments STEPHANE DE SAKUTIN AFP / Archives
Then, patients with "severe or critical form and who are HIV negative", that is, who have not developed antibodies after infection or vaccination.
It is mainly for patients with a deficient immune system (the "immunocompromised"), in whom the vaccination is not effective, that this injectable treatment raises hopes.
It was designed by the biotechnology company Regeneron, in partnership with the Roche laboratory.
A major obstacle, however: its price (2,000 dollars per dose according to NGOs), which the WHO hopes to see lower.
THOSE WE TEST
- Oral antivirals: several laboratories are working on the trail of swallowable antivirals in tablet form.
One of the most advanced is molnupiravir (a partnership between biotech company Ridgeback Biotherapeutics and MSD lab).
It is the subject of clinical trials on patients (hospitalized or not) and also in prevention in people who have been in contact with infected people.
The results could be known by the end of the year.
The biotech Atea Pharmaceuticals and the Roche laboratory are evaluating the effectiveness of a comparable treatment, called AT-527.
Finally, Pfizer is developing a drug combining two molecules, including ritonavir, already widely used against HIV, the AIDS virus.
The market for such treatments "effective and easy to take in the early forms of Covid would be potentially huge", recently underlined the infectious disease specialist Karine Lacombe during a press briefing by the French research agency ANRS / Emerging infectious diseases .
This is why it is necessary to "take with precaution" the sometimes thunderous announcements of the industrialists, and to await the results of the clinical trials.
Especially since in general, antiviral drugs have so far not been very convincing against Covid.
- New generation antibodies: some laboratories are working on long-acting monoclonal antibodies.
One, sotrovimab, is being developed by GSK and was ranked at the end of June by the European Commission as one of the five most promising treatments.
The other, AZD7442, is an antibody cocktail designed by AstraZeneca, which unveiled preliminary results at the end of August.
The laboratory ensures that it can be effective in preventing Covid in fragile patients.
Finally, a French company, Xenothera, is working on another type of synthetic antibody, called "polyclonal antibodies".
Its product, XAV-19, is based on antibodies of porcine origin modified to be "humanized".
He is in the home stretch of his clinical trials.
THOSE WHO DON'T WALK
Since the start of the pandemic, several treatments have disappointed.
This is the case of hydroxychloroquine (promoted by French researcher Didier Raoult), remdesivir (initially considered very promising), ivermectin and the lopinavir-ritonavir combination (Kaletra of its trade name), used against the AIDS virus.
A bottle of hydroxychloroquine tablets in a pharmacy in Provo, May 20, 2020 in Utah GEORGE FREY AFP / Archives
Over time, all of them have been advised against by the WHO to fight against Covid.
They have the common feature of being "repositioned" drugs, that is to say initially intended for another use but tested against this new disease.
"Repositioning a drug is what we do urgently at the very beginning of a pandemic," explained Karine Lacombe.
However, except the anti-IL-6, all disappointed, which according to her shows "the limit" of repositioning.
"This is why we are entering another therapeutic era by developing drugs specific to SARS-CoV-2", the Covid virus, the specialist concluded.
© 2021 AFP