Covid-19: messenger RNA vaccines would prevent contamination
Messenger RNA vaccines, such as those from Pfizer and Moderna, would significantly reduce the risk of being infected with Covid-19.
Kenzo Tribouillard AFP / File
Text by: Simon Rozé Follow
5 mins
While France will begin its third national confinement, with a closure of schools for three weeks, good news is reaching us from the United States.
Messenger RNA vaccines would prevent contamination well.
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Since their first clinical trials, the question remained unanswered: in addition to preventing symptomatic forms of Covid-19, do vaccines also prevent the spread of the virus?
In the United States, a study by the Center for Disease Control (CDC) provides
some answers
that go in the right direction.
Four thousand people vaccinated with an RNA vaccine, those of Moderna and Pfizer / BioNTech, were followed.
Fourteen days after the second dose, 90% of them were declared completely immune: the virus cannot pass through them at all.
They therefore logically cannot transmit it.
The effect is also present after the injection of the first dose, although it is less: this concerns 80% of the vaccinated.
The implications in terms of epidemic control are very interesting: it does indeed change a lot of things if the vaccinated people constitute a wall against the spread of the epidemic.
The CDC therefore recommends opening the vaccination to everyone.
Children and vaccines
It would still have to be possible.
Indeed, apart from the contingencies of stocks which have pushed the health authorities of several countries to vaccinate the most vulnerable as a priority, a part of the population remains completely excluded from the systems: children and adolescents.
However, we can see that the virus is actively circulating among them.
The reason is simple.
The clinical trials had not enrolled people under the age of 18.
Without data, they are therefore currently excluded from vaccination campaigns.
However, that is changing.
Several clinical trials around the world have been launched to obtain this knowledge and the first results are coming.
Pfizer announces 100% effectiveness
of its vaccine in 12-15 year olds to prevent symptomatic forms of Covid-19.
This is an impressive figure that should however be put into perspective.
This study was carried out on nearly 2300 adolescents and it concerns only the symptomatic forms.
However, we know that this population most generally declares forms without symptoms.
In parallel, therefore, it will be necessary to determine whether the effects on the carriage of the virus mentioned above are also present.
In addition, this announcement was made once again by press release.
We will therefore have to wait for the publication of complete data to have a more precise idea.
However, this does not prevent the laboratory from wanting to submit these results soon to the American and European health authorities.
He intends to request the extension to these age groups of the authorization of his vaccine.
Covid-19 and influenza
That was one of the concerns this winter: would the seasonal flu epidemic be added to that of Covid-19?
In fact, the flu kills between 10,000 and 15,000 people every year in France and each time clutters the resuscitation services.
Good news, that hasn't been the case this season.
Indeed, according to the
report of Public Health France
, published Wednesday, March 31, no person sick with influenza has passed through the doors of one of the 226 intensive care units which has been monitoring the epidemic since the month of October.
We probably owe this result to vaccination: last winter's campaign was particularly effective.
The barrier gestures are also very certainly to be thanked.
We know that they work against Covid-19 and they are just as effective against the flu.
We have also seen their effect on other diseases such as bronchiolitis and gastroenteritis, much less present this year than usual.
Treatment suspended in the United States
Business with bamlanivimab is not getting better.
This monoclonal antibody-based treatment was authorized in France on February 12.
This authorization had however led to a controversy
and caused misunderstanding, it was indeed based only on a clinical trial not very convincing.
This week,
the American health authorities announced that they had stopped distributing this treatment
: in question, its ineffectiveness in the face of variants.
It will still be possible to find it in the United States.
Its use as a cocktail with another monoclonal antibody, etesevimab, is in fact still recommended.
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