Covid-19: hopes for collective immunity undermined, vaccinating quickly remains the priority – The HuffPost

ALAIN JOCARD via AFP

CORONAVIRUS – Last spring he had nothing but that in his mouth. “The next goal is collective immunity”, wrote Olivier Véran, June 12, 2021 on Twitter. Three weeks later, same minister, same platform: “It is a collective challenge to reach thecollective immunity, let’s take it up together! ”.

The idea was still there, at the time, to be able to vaccinate the population to the point where the virus no longer finds enough potential hosts and disappears: a track that was considered the ultimate way to put an end to it. the Covid-19.

Vaccines reduce the risk of severe form, including with the delta variant. Vaccinated, we infect ourselves much less, we transmit much less, and we no longer live under stress. It is a collective challenge to achieve collective immunity, let’s meet it together!

– Olivier Véran (@olivierveran) July 4, 2021

A myth”

But since then, motus. At the Ministry of Health, during a press point on the vaccine strategy on Tuesday, August 17, we hesitate: “We will not comment on our chances of reaching thecollective immunitybecause there is no consensus. ”

“The vision that we can have of group immunity today is unfortunately not that of eighteen or even six months ago”, also conceded Alain Fischer, the president of the Council of orientation of the vaccination strategy, in an interview with the JDD this week-end.

A few days earlier, his Anglo-Saxon counterpart Andrew Pollard, the Oxford infectious disease specialist, showered the last hopes of UK MPs, speaking of a “myth”.

The reason: the Delta variant, much more contagious than Alpha, which jeopardizes hopes of achieving collective immunity. For this, it will be necessary to vaccinate more than 90% of the population, and above all, that the vaccines prevent any infection.

However, apart from Moderna, vaccines do little to prevent Covid-19 infections. A pre-publication, posted on August 9 on the medrxiv platform, which lists the studies being reviewed, identifies approximately three times more infection by the Delta variant in unvaccinated than in vaccinated, which is equivalent to protection against infections of ‘only around 42%.

Achieving collective immunity means aiming for the extinction of the virus, by limiting the number of potentially infected people. With Delta and imperfect vaccines, this seems less and less likely. But that doesn’t mean that all is lost.

“Zero serious form” strategy

RNA vaccines, the majority in France, prevent more than 75% of serious forms of Covid-19: this is all hospitalizations avoided. If the epidemic does not go away, but the public hospital is relieved, the trick is played: “Thanks to the vaccine, we can avoid the closures”, summed up Emmanuel Macron on August 11 at a press conference.

“The collective immunity strategy falls apart and makes people think about adopting a strategy of zero hospitalization, zero serious form”, bounces on Twitter Clarisse Audigier-Valette, head of the Covid unit at Toulon University Hospital, on August 12, visibly annoyed by this debate, which is essentially semantic and technical. Collective immunity or not, the more rapidly the vaccination coverage increases, the less the 4th wave will affect hospital services, according to the models of Pasteur.

In addition, “vaccinating quickly reduces the risk of the emergence of a vaccine-resistant variant”, according to a model that takes into account the spread of Covid-19 and its rate of mutation, published in Nature, on July 30th. Thus, with or without hope of eradicating the virus, the objective is the same: to vaccinate the more, the faster. “It does not change our strategy”, punctuates Fischer, in the JDD.