Covid-19: ivermectin ineffective according to a study, and other scientific news
Despite encouraging results, ivermectin has not shown a clinical effect on the coronavirus © South African Police Service (SAPS)
Text by: Simon Rozé Follow
5 mins
Despite encouraging results in vitro, ivermectin has not shown a clinical effect on the coronavirus, according to a study published by the Journal of the American Medical Association (JAMA).
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Ivermectin is an
anti-parasitic
that has made a lot of talk in recent weeks.
In question, the hope raised by good results in the laboratory and during preliminary clinical studies.
Alas, a larger test brings a denial.
His results are published
in
JAMA
.
Its authors recruited 400 patients with moderate Covid-19.
They were separated into two groups, one receiving a placebo, the other receiving ivermectin for five days.
After three weeks of observation, the researchers found no difference between the two groups, whether in terms of healing time, worsening or not of the patient's condition or even mortality.
This is therefore a new example of the fact that a good result
in vitro in
no way prejudges an efficacy in real life,
in vivo.
“There are several phenomena,”
explains Stéphane Gaudry, professor of intensive medicine and intensive care at the AP-HP Avicenne hospital in Bobigny.
“First of all, there is the nature of the drug used
,” he explains.
This is a cartoonish example, but if you put bleach it will break everything, there will be no more viral replication.
But of course you are not going to give the sick person bleach!
The product must be tolerated by the body.
The second element is concentration.
What you put in your
in vitro
culture dish
must be able to be comparable with what you will find in the body.
If the drug administered to the patient is a hundred times less concentrated than by putting it directly on the cells in the laboratory, it will obviously not have the same effectiveness.
Finally, there is the question of interactions: in your box where you do the
in vitro
work
, there are only two or three components.
In the human body there are tens of thousands which can interfere with the effect of the drug
”.
For all these reasons, it is therefore not necessary to conclude that a drug is effective on the sole basis of results obtained in the laboratory.
The latter can only indicate an interesting track that should be checked in a more robust way.
Group A more affected?
It has now been more than a year since Covid-19 has been known, and yet we continue to learn more about how it works, and in particular why some people develop severe forms while others do not.
It had thus been observed that patients with blood group A developed these severe forms more than those of other groups.
It was only an observation then.
However, we are beginning to discover the reasons for this.
We read in the journal
Blood Advances
, published by the American Society of Hematology, a study that could explain this phenomenon.
To enter our cells, the Sars-CoV-2 responsible for Covid-19 uses a kind of key, called S protein, or spicule.
If there is a key, then there is a lock on our cells: the ACE2 receiver.
It is mainly found on our lung cells, which is why Covid-19 is primarily a respiratory disease.
According to the authors of this study, the spicule can also recognize blood groups.
There are four: A, B, O and AB, which have their particularities.
These prevent, for example, transfusions between people without taking it into account, otherwise the immune system could turn against blood it considers foreign.
These markers, these differences are called antigens, and it turns out that in addition to the ACE2 receptor, the S protein of the coronavirus can open a second lock: the blood group A antigen expressed in the lung wall.
The Sars-Cov-2 thus has a second entry point there.
Towards a fourth vaccine in Europe
The European Medicines Agency (EMA) decides this Thursday, March 11 for approval of the vaccine developed by Johnson & Johnson.
Administered in a single dose, it has good efficacy,
which is relatively stable in the face of variants.
The United States and Canada have already approved it.
It would join the vaccines of Pfizer / BioNtech, Moderna and Astra Zeneca in Europe.
However, once again there are concerns about the laboratory's ability to deliver the expected doses.
In total, 55 million are expected by June, but already, Johnson & Johnson say they are
"under tension
" and warn that this could prevent it from keeping its commitment.
► (Re) listen: South Africa: ivermectin floods the black market as a drug against Covid-19
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