The cross : In view of the current situation, is a fourth dose of vaccine necessary?
Alain Fischer: The question arises, but today there is no element which allows to decide. In a context where Omicron is less sensitive to vaccination, it is a question of how long we are protected from this virus with three doses. We know that three months after the booster, protection against infection decreases, and more with the Pfizer vaccine than with Moderna.
British data also shows that three months after the booster, protection against hospitalization is still 90% effective. For the months of November and December we did not observe a significant increase in the number of hospitalizations of people having had a recall. These bits of information on protection against severe forms are so far rather reassuring and today there is no signal to suggest that immunity is crumbling.
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But the information we have is still very incomplete, and we are constantly on the lookout for additional information from France and countries that started recalls earlier than us, such as Israel. In the current state of affairs, we can have additional information in two weeks as well as in three months. One can also imagine that the immunity will remain stable for a long time, which is not excluded.
Who would be affected by this possible fourth dose?
A. F. : Already, there are people who are very deeply immunocompromised and those around them, to whom it is reasonable to offer a second booster. This is an instruction that has already existed for a few months and concerns around 200,000 people. For the rest of the population, discussions on this possible second recall concern people over the age of 65, people with co-morbidities and health professionals. For the moment, our reflection does not relate to the whole of the population because there are no elements which encourage to generalize this booster dose, which in addition could give the signal to the population that it need to be vaccinated often.
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In terms of vaccination priority, the main thing is that the 25% of people over 65 who have not yet received their booster receive their 3e dose, in addition to continuing the first and second doses.
The reminder (3e dose) remain mandatory even if we contract Covid-19 after having received two doses of the vaccine?
A. F. : These are the guidelines that apply today, but this is a matter under discussion. This directive is subject to change. The position of the Orientation Council for the vaccination strategy is as follows: for people who contracted the virus more than three months after the complete primary vaccination (two doses), this infection is worth a booster and it is not necessary to receive a new injection.
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If, on the other hand, this infection has occurred less than three months after the first vaccination, it will not be worth a booster because the interval is insufficient to have the “booster” effect on the immune memory, which we have conventionally with a booster. In this case, it would be reasonable to consider a booster two or three months after this infection. At this point, that is simply the Council’s point of view. On the other hand, during the primary vaccination (administration of the first two doses) one infection is equivalent to one dose.
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