On September 20, the High Authority for Health (HAS) confirmed its recommendation to administer the three bivalent vaccines in booster doses against Covid-19, for people at risk. Two weeks later, and after the start of the vaccination campaign on October 3, the World Health Organization (WHO) pointed to the lack of data regarding the ability of these vaccines to target Omicron. If it is proven that they are just as effective as the first vaccines, thanks to laboratory data, for the time being, nothing proves that they are more so.
While the Omicron variant has been in the majority for almost a year in France, bivalent vaccines have recently been recommended by the HAS: “The clinical efficacy expected for these new bivalent vaccines is at least equivalent, or even superior, to that of the original monovalent vaccines, without this probable superiority currently being able to be demonstrated in real life. »
“Future vaccines cannot be evaluated like the first ones”
So why do WHO experts claim that it “there is not yet enough data to be able to recommend vaccines against Covid-19 specifically targeting the Omicron variant compared to the original strains” ? Daniel Floret, Vice-President of the HAS Vaccination Techniques Commission, specifies that the data available are laboratory data, which is sufficient to confirm that bivalent vaccines are at least as effective as monovalent vaccines, but confirms that the WHO “is not wrong when he claims not to know precisely the benefit of bivalent vaccines”.
However, “we know that the first generation vaccines have allowed a certain level of antibodies, and that the effects obtained are not debatable, so as we obtain equal or even higher levels of antibodies with the new vaccines, we can say that they will be at least as effective”, he reassures.
The data that we do not have are clinical data: “Future vaccines cannot be evaluated like the first ones, it is no longer possible, because a large part of the population has already been vaccinated, so the panel would be more limited, and today we know what works. »
“We still have vaccines that work in large quantities”
In the absence of clinical trials, “the actual effects verified in the field in several months will confirm whether or not these bivalent vaccines target Omicron more”, also explains Yannick Simonin, virologist at the University of Montpellier. According to the researcher, the caution of the WHO is twofold.
In addition to the impossibility of asserting that bivalent vaccines are more effective for Omicron, their priority is to recall that “we still have vaccines that work in large quantities: let’s use them as we approach a possible winter epidemic resumption”.
With this declaration, the WHO recalls, according to him, that“we should not wait for the better efficacy of bivalent vaccines to be proven, but above all vaccinate in countries that have less access to them, and administer booster doses, whether bivalent vaccines or not”.