June 30, 2022

towards a fourth dose of vaccine?

Are we heading towards a fourth dose of vaccine? Faced with the increase in contaminations, the Minister of Health Olivier Véran declared that an additional injection was “a possibility”.

It could, in theory, reactivate antibodies and protect against Covid-19. But for the moment, “we have no hindsight on the duration of the effectiveness” of the vaccine, noted the minister at a press conference on December 27. The question of the fourth dose “will come in due time”.

Some countries have already taken the plunge. This is the case of Israel, which administered a fourth dose of the vaccine to 150 volunteer caregivers on December 27. This clinical trial is expected to precede the launch of a nationwide recall campaign. Prime Minister Naftali Bennett did not wait for the results to announce that those over 60 and medical staff would soon be entitled to an additional injection.

Since then, several states have aligned themselves with this position. Chile will administer a fourth dose to those at risk from February. In Brazil, immunocompromised people will receive the new injection. Peru has ordered several million doses of vaccine for an additional recall campaign.

WHO puzzled

This strategy is far from unanimous. The World Health Organization (WHO), already skeptical about the third dose, has reaffirmed its position: “No country will be able to get out of the pandemic with booster doses”, warned its director, Tedros Adhanom Ghebreyesus. “It’s important to remember that the vast majority of hospitalizations and deaths are people who haven’t been vaccinated, not people who haven’t had a booster dose.”

At this time, there are no scientific studies on the effectiveness of a fourth dose. The one carried out on caregivers in Israel will therefore be the first of its kind. Note that the Hebrew state was already the first to launch its vaccination campaign against Covid-19, a year earlier.

In France, 90% of the vaccine-eligible population received their first two injections and 38% received a booster dose. The government announced yesterday that the time to get a third dose has been reduced to three months.