Chloroquine, hydroxychloroquine and Covid-19: where are we ?

Chloroquine, hydroxychloroquine et Covid-19: où en est-on ?

A scientist shows packaging of Nivaquine and Plaqueril, two substances that contain hydroxychloroquine, the university hospital Institute in infectious diseases Marseille, on the 26th of February last.

26 march 2020 14h56


Chloroquine, hydroxychloroquine and Covid-19: where are we ?

Julie Charpentrat

Agence France-Presse


PARIS – Studies, trials, practices: what do we know of chloroquine and its derivative hydroxychloroquine, currently experienced, along with other molecules, in several countries against the Covid-19 ?

That is what it is ?

It is an antimalarial drug is prescribed for several decades against malaria, a parasite carried by the mosquito. Chloroquine is known under several trade names, depending on the country and the laboratories that produce them: Nivaquine or Resochin, for example.

There is a derivative, hydroxychloroquine, better tolerated, known in France under the name of Plaquenil, which is used against lupus or rheumatoid arthritis.

The side effects are many : nausea, vomiting, skin rash, but also with ophthalmological, cardiac, neurological,… An overdose of chloroquine can be especially dangerous, even deadly.

Why is there the hope ?

In waiting for a hypothetical vaccine, which could be available in a year or more of very many scientific teams test several existing drugs and combinations of drugs to try to find the faster a treatment.

Compared to other molecules, chloroquine and hydroxychloroquine have the advantage of being already available, cheap and well known, where the particular interest they arouse.

Even before the current outbreak of SARS-CoV-2, the antiviral properties of chloroquine, have been the subject of a multitude of studies, in vitro or on animals and on different viruses, with contrasting results.

“It is known since a long time as chloroquine (C) and its derivative hydroxychloroquine (HC), inhibit in vitro the replication of some viruses, recalls Marc Lecuit, biology researcher of the infections at the Pasteur institute.

And therefore, “it was shown a few weeks ago that, as expected, the C and the HC have antiviral activity on SARS-CoV-2 in vitro,” he says.

But “this does not necessarily imply, however, that these drugs have antiviral activity in vivo in humans,” he continued, recalling that “there have been many trials were disappointing, regarding the dengue virus (not for profit) or chikungunya (deleterious effect)” (the molecule to “help” the virus to grow).

Hence the caution with which call of many scientists, as well as the world Health Organization or the French health authorities or the u.s., who are launching clinical trials of regulated, large-scale to determine if chloroquine, but also other molecules – actually has an efficiency on the Covid and that its use is safe, before you generalize.

Why is it controversial ?

Two publications, one chinese and one French, are part of positive results with clinical trials, that is to say, on real patients Covid.

But many scientists and WHO point out the limitations, particularly because they focus on too few patients and that they were not conducted according to scientific protocols standards (draw patients, doctors and patients ignorant of who receives the treatment, results have been published in a scientific journal, to the committee of independent reading etc…).

Tests chinese have focused on a hundred people in different hospitals and concluded on the positive effects of the chloroquine.

In France, twenty patients received hydroxychloroquine, and, for some, in addition, the antibiotic azithromycin.

“Despite the small sample size, our study shows that treatment with hydroxychloroquine is associated, significantly, to a decrease/disappearance of the viral load (…) and its effects are reinforced by azithromycin,” according to the study co-signed by professor Didier Raoult, of the University Hospital Institute (IHU) Méditerranée infection.

Evidence of the complexity of the subject, another clinical study in chinese -published in the march 6 – has not, however, found to be of particular effectiveness on 30 patients.

“There is no study that shows anything about the effectiveness in vivo,” sums up Christophe D Enfert, scientific director of the Pasteur Institute.

“These questions absolutely do not want to say that the HC has no interest in the treatment of Covid”, but “for the knowledge, it should be evaluated scientifically by following the methodology of clinical trials”, according to Marc Lecuit.

So there are a hand, some doctors, some country, but also of the elect who call to administer largely of hydroxychloroquine in the name of the health emergency.

The other, a part of the scientific community and health organizations who call to wait for the results validated according to the strict orthodoxy of science to generalize the treatment.

Who uses it against the Covid-19?

Given the explosion of requests of chloroquine and hydroxycholoroquine for several weeks, it can be assumed that doctors in the world have been able to prescribe, in their soul and consciousness, to patients with Covid, or hoping to protect.

The Pr Raoult has promised about him publicly of distributing a combination of hydroxycholoroquine and azythromicine to “all infected patients”.

Several countries allow its use against the Covid, but the question remains, in what context.

For example, in France, hydroxychloroquine (but also of antiviral medications lopinavir/ritonavir) is permitted as a derogation to the hospital, under the responsibility of the doctors and only for severe cases of Covid-19.

However, in Morocco, he called the hospital and regional Health directors to “the introduction” of chloroquine and hydroxychloroquine for “confirmed cases”.

For clinical trials, a european trial baptised Discovery has been launched in several countries, including France, to test four treatments, including the hydroxycholoroquine, on to 3,200 patients, 800 cases of serious in France.

Results are expected in the coming weeks.

In the United States, the FDA, which oversees the marketing of medicines, has announced “a wide clinical trial”.

The WHO has also launched a large international clinical trial.

Le Soleil

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