Covid-19: Did Jean Castex lie when he said that the vaccine prevented contamination? – LCI

It is the turn of the Prime Minister, Jean Castex, to be positive for Covid-19 despite his two doses of AstraZeneca administered last summer. It did not take more for opponents of vaccines to make his case a new argument in their favor. If Marine Le Pen is not antivax – she is vaccinated against Covid and publicly recognizes the effectiveness against severe forms of the disease -, she however seized this news to denounce the “lies” and the “enormities” government on the subject of vaccination.

Invited this Tuesday, November 23 on France Inter, the presidential candidate and leader of the National Rally targeted a particular moment : “I could still hear Mr. Castex this morning in replay explaining to us that the vaccine would prevent catching the Covid and infecting others. It was a lie. Why lie to the population?”. Difficult however to speak of “lies” on the part of the government: this is the context that needs to be re-situated.

Marine Le Pen referred here to a television passage by Jean Castex dating from July 21. Here is what the head of government said, live from the TF1 set: “Vaccination, it works. We have found that people who have two doses, until then, when they passed a person who was contaminated, had to be in contact and isolate themselves. Analyzes made on these people show that ‘ they no longer have a chance of catching the disease. So from this afternoon we are going to abolish the obligation to be in contact “. An affirmation then serving as an argument to no longer link the obligation to isolate oneself for ten days to the status of contact case. And encourage the French to get vaccinated.

At that time, the government was already relying heavily on the vaccination campaign, which it saw as the only solution to end the epidemic. On July 8, Olivier Véran mentioned for example the vaccine “100% effective against containment” (statement that we have recontextualized here) and on the 12th of the same month, Emmanuel Macron announced the health pass in leisure establishments and the vaccination obligation for caregivers. So much for the political context.

Now, what did we know in mid-July, when Jean Castex uttered this sentence on the TF1 set, on vaccine efficacy in the light of the Delta variant? What was science saying about the benefits of the vaccine on the risk of infection?

On July 6, thehe Scientific Council took stock on the state of scientific knowledge, in an opinion submitted to the government. He then noticed that “The efficacy of vaccines against the B.1.617.2 (Delta) variant could not be formally tested in clinical trials, as the Delta variant was not circulating at the time when most of the clinical trials were carried out. The data we have to assess vaccine efficacy come from laboratory studies and ‘real life’ studies in people who have been vaccinated with Pfizer and Astra-Zeneca vaccines in the UK. ”

From observations made in the laboratory, the Scientific Council described “a moderately or strongly diminished neutralizing capacity against the Delta variant”. From the observations of the vaccinated in the United Kingdom, the Scientific Council was responsible for “real-life vaccine efficacy estimates against symptomatic forms” of “33% and 60% after one and two doses of Astra-Zeneca, respectively; and 33% and 88% after one and two doses of Pfizer, respectively”.

Protection not totally guaranteed, therefore, but already very high against the risk of developing a symptomatic form of the disease. However, as we know, the immunity acquired by vaccination decreases over time and has been weakened by the Delta variant, which is much more contagious than the original strain.

Here is what the Scientific Council said on October 5, in a new opinion made public, in the light of the new knowledge available: “Recent data available to us from Israel, the United States, and the United Kingdom show a decline in vaccine efficacy against symptomatic Delta variant infection with protection that drops to 90% two months after the second. 50% dose six months after the second dose “. The Scientific Council explained this reduction in the effect of the vaccine on infection by “the combined result of a decrease in the concentration of circulating neutralizing antibodies, and the ‘aggressiveness’ of the Delta variant” characterized by a period of“shorter incubation” and “higher viral loads”.

This being the case, the effectiveness of vaccines remains convincing on the risk of developing a severe form of Covid and of being hospitalized: this is still evaluated at 90% six months after a second dose, recalled the Scientific Council in the same. note, against an estimated protection this summer at 96% in the case of the Pfizer vaccine.

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