Vaccines that raise questions. The green light recently given to new bivalent vaccines, which target the original strain of the coronavirus but also its variant Omicron, questions some of the scientists. On Twitter, epidemiologist Antoine Flahault said that health regulators had “bypassed the usual stages of the approval of a vaccine” by accepting a reduced number of tests. Franceinfo returns to the validation conditions for these vaccines which will be available from October 3 in France.
Health authorities have been more flexible on their criteria
On September 1, the European Medicines Agency (EMA) gave a favorable opinion on the use of two bivalent vaccines: vaccines from Moderna and Pfizer BioNTech that target the original strain and the Omicron BA.1 variant. They were joined on September 12 by a third vaccine, that of Pfizer BioNTech which targets the original strain and the Omicron BA.4 and BA.5 variants. In France, the High Authority for Health (HAS) included these new vaccines in its recommendations on September 20, “in an epidemic context marked by the majority circulation of the BA.5 sub-variant”, specifies the college of experts.
In detail, however, it appears that these decisions are based on fewer tests than for previous serums. The last vaccine has also been authorized while it is still in the human clinical trial phase, explains the HAS in its recommendation. The authority assumes that this procedure is “based on more limited data than in an initial assessment” and explain that this “makes it possible to ensure the very rapid availability of the vaccines most suited to the epidemiological context and the circulating strain”.
HAS also invokes “the significant decline acquired since the beginning of the health crisis concerning mRNA vaccines” added to “the experience gained with vaccines adapted to circulating strains” – knowledge which, still according to the HAS, “justify and authorize the appeal” to these less complete data.
These three vaccines have indeed been tested (or are being tested) on humans
Sera suitable for Omicron’s first subvariant (BA.1) have been well tested on humans in clinical trials. The EMA specifies in a follow-up document (in English) that these experiments concerned various age groups and date back to March 2021 for the oldest, in the case of the Pfizer / BioNTech vaccine. The results of these studies have been reviewed by the EMA and the HAS. The latter ensures that “the clinical efficacy expected for these new bivalent vaccines is at least equivalent or even superior to that of the original vaccines” – even if the public authority emphasizes that this “probable superiority” could not yet be “demonstrated in real life”.
As for the third vaccine, which targets Omicron BA.4 and BA.5 variants, its development “is primarily based on a preclinical study in mice, and two clinical studies (on humans)”, specifies the HAS. At European level, the EMA justifies its express authorization by the great similarity between the bivalent vaccines. “Extrapolating results from one vaccine to another is a scientifically established and documented approach, based on widely accepted immunology concepts“, explained Marco Cavaleri, the person in charge of the vaccine strategy of the EMA, quoted by AFP.
A risk for “public trust” according to Antoine Flahault
The epidemiologist, who does not openly question the clinical effectiveness of these vaccines, is above all concerned about the political recoveries of these authorizations. “The antivax are having a blast, they couldn’t dream of a better holy bread”, he said for example on Twitter. The scientist fears one scenario in particular: if these bivalent vaccines prove to be less effective than expected, this would cause “a sharp drop in public confidence” in the vaccine policy according to him.
As a precaution, Antoine Flahault recommends varying the instruments for combating the Covid-19 epidemic, for example by offering a fourth monovalent dose (the type of vaccine proposed so far), by relaunching the vaccination of the youngest or by reintroducing the wearing of masks in enclosed spaces.
While an eighth epidemic wave seems to be looming (13,768 hospitalizations in the space of a week, an increase of 7%), the debate on health measures remains open. For Sandrine Sarrazin, researcher at the National Institute of Health and Medical Research (Inserm), updating vaccines promises increased efficiency. “We are adapting to the variants that are currently circulating, she explained to the magazine Our time. People vaccinated with this bivalent will therefore produce antibodies that are a little better sharpened. Prudent, the HAS specifies that it may review its recommendations “particularly with regard to the full results of ongoing trials, future trials and European pharmacovigilance data”.