Already put in place by Israel, will the fourth dose of vaccine against the coronavirus be adopted by other countries to fight against the meteoric rise of the Omicron variant?

In France, "the fourth dose of vaccination is a possibility," French Minister of Health Olivier Véran said Monday at a press conference.

"We are totally open to this prospect," said the Minister of Health.

These comments come at a time when an anti-Covid vaccination booster campaign, often called a "third dose", is already underway in France and other developed countries, in order to compensate for the rapid loss of efficacy of vaccines against the virus. coronavirus infection.

Doubts about the period of immunity

Why ever think about the next step?

Because of the dazzling arrival of the Omicron variant, particularly contagious and already dominant in several countries such as the United States.

More than any previous incarnation of the virus, like Delta, Omicron is putting existing vaccines to the test.

They protect much less against infection with this variant even if vaccines, like that of Pfizer / BioNTech, seem to remain quite effective against the severe forms.

We know that a booster dose of certain vaccines - Pfizer, Moderna, AstraZeneca - considerably boosts immunity to Omicron.

Hence the acceleration of “third dose” campaigns in several countries.

But it is not yet clear for how long the booster dose gives this renewed immunity.

This is why some countries are already considering a "fourth dose", in other words a second booster, for the most fragile, especially the elderly.

Real interest not yet measured

This is the case with Israel. Just before Christmas, his government announced that all residents over the age of 60, as well as caregivers, would soon be entitled to an extra dose. As often, this country, which very early launched its first anti-Covid vaccination campaigns a year ago, is in a pioneering position in this area. In France, Olivier Véran also said to wait to see what would happen in Israel to judge the advisability of a fourth dose.

But this is not unanimous, as evidenced by a certain vagueness in Israel.

While his government initially hinted at an imminent campaign among the population, the fourth doses eventually only began to be distributed there in limited cases, in clinical trials.

That's the whole problem: we must first determine the real interest of a new booster dose, or even its possible risks, while there is currently no concrete data on the matter.

"Too early" for the White House

This uncertainty leads several experts to warn against a runaway, like the American Anthony Fauci, main adviser to the White House in the fight against the pandemic. "It's too early to talk about a fourth dose," he told US radio, first deeming it essential to know how long the current boosters - the third doses - will remain effective against Omicron.

"If their protection lasts much longer than in those who have only received two doses, it could be a good time without needing a fourth," he said.

Behind these questions, there is a fundamental uncertainty, still unresolved, about the very nature of the third dose.

Should it be considered as an outcome which complements the initial vaccination in two doses by increasing the immunity conferred?

Or is it rather the first in a long series of reminders, such as the seasonal flu shot, which is renewed each year?

Updated versions of the vaccine rather than a fourth dose

In the latter case, however, it would appear more logical not to give a fourth dose of a current vaccine, but to wait for updated versions against Omicron.

It is the same idea as that of the flu vaccines which change every year to adapt to the evolution of the virus.

Our vaccination dossier

“Very clearly, what will be needed (…) is a 2.0 vaccine,” French infectious disease specialist Benjamin Davido said on Tuesday on RMC radio, counting on “a messenger RNA vaccine suitable for Omicron”.

The two producers of messenger RNA vaccines, Pfizer / BioNTech and Moderna, have already promised an anti-Omicron version.

But, even if this technology is a priori easier to adapt to a new incarnation of the virus, the deadlines remain uncertain.

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  • Omicron variant

  • Video

  • Anti-covid vaccine

  • Health

  • Covid 19

  • Coronavirus

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