Could the vaccine booster campaign soon evolve, given the progression of the Omicron variant of Covid-19? The hypothesis is put forward, particularly about the Moderna vaccine. In its last opinion, Wednesday, December 8, the Scientific Council mentioned a possible increase in the dosage of the booster injection from the American laboratory, in a context of a surge in cases of contamination with the Omicron variant.
“Moderna vaccine can be given to people over 30 years of age with equivalent efficacy to Pfizer vaccine and without additional risk. The booster dose of Moderna is currently 50 micrograms. It may be increased in the coming weeks. at 100 micrograms to induce a better immunological response to the Omicron variant “, develops the body advising the government on the response to the pandemic. What do the current recommendations say about the dosage of the third injection of Moderna? What are the elements that lead the Scientific Council to make this proposal?
The initial data presented by Moderna on its booster dose showed, as of May, a simple half-dose administered to patients who have already received two doses of the Covid-19 vaccine. In a press release *, the American company explained that its preliminary data, from phase 2 trials, already showed “than a single dose of 50 micrograms”, given as a reminder, “increased the responses of neutralizing antibody titers against Sars-CoV-2 and two variants of concern”, the Beta and Gamma variants.
These early data followed in official recommendations. In October, the European Medicines Agency (EMA) approved a third dose of 50 micrograms of Moderna’s Spikevax vaccine, six months after their second dose was given. “This recommendation is based on clinical evidence that a booster dose of 50 micrograms results in a strong immune response against Covid-19”, then underlined Moderna *. A few weeks later, the US Food and Drug Administration (FDA) in turn approved the use of 50 microgram doses of the Moderna vaccine in the recall campaign, the laboratory notes *.
More recently, the Cov-Boost * study, conducted in the United Kingdom, evaluated the effectiveness of several booster doses of vaccines against Covid-19, including that of Moderna. Comparing the protection provided by a full dose and a half dose of Pfizer vaccine, these researchers found that half a dose resulted in “minimal decline” of the immune response capacity. They concluded that full doses of the messenger RNA vaccine, including that of Moderna, are greater than the dosage needed to elicit an effective immune response. And therefore that half-doses are sufficient, while allowing “to dramatically increase the number of doses available worldwide.”
But we can also read the study in another way: it shows that we can also give a full dose of vaccine as a booster, and that this results in a better immune response, although “minimal”.
The British study, published on December 2, was carried out upstream of the spread of the Omicron variant. However, it is this situation which is of particular concern to the Scientific Council, and invites it to formulate an increase in the booster dose of Moderna.
“Over the past ten days, the emergence of a new variant called Omicron has been added, whose mutational profile appears worrying, and for which the first available information suggests that it is spreading extremely quickly”, recalls the instance in its last opinion. “Its rapidity of propagation in a largely immune population suggests that it has a very substantial immune escape capacity. (…) Current vaccines have reduced efficacy”, even if she stays “preserved”.
Asked by The Parisian, Denis Malvy, infectious disease specialist at Bordeaux University Hospital and member of the Scientific Council, confirms that the evolution of the epidemic situation linked to the Omicron variant has led the body to consider this option of a higher dosage. “To fight against the Delta variant, half a dose of Moderna equals a dose of Pfizer. This is more than enough (…). There is no hesitation in this place”, he recalls at first. Corn “We know that the Omicron variant risks causing a small immune escape. If the protection was much less good, one option would be to go back to a larger quantity”, he defends with the daily newspaper.
* These links refer to pages in English.