Jean-François DELFRAYY: “We did not expected that fourth wave would slow down so quickly”

The president of the scientific council is called “quite optimistic” on the evolution of the epidemic of Covid-19 in France, even though the occurrence of a new variant can not be totally excluded.

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Professor Jean-François DELFRAYY, Immunologist and in addition Chairman of the National Ethics Advisory Committee (CCNE) since 2016, took the chairmanship of the Cvid-19 Scientific Council in March 2020, to advise the Government in the fight. against the pandemic. It returns to Le Monde on the different scenarios of possible evolution.

Despite the start of the school year and the return of the French to the office, the number of cases continues to fall. Are you surprised?

Yes. We did not expected that the fourth wave would slow down so quickly. This can be explained in part by the very high level of vaccination in France and by the very high efficiency of vaccines, unexpected magnitude. There are probably other factors that escape us a little. This does not mean that the fourth wave is completely behind us. With the arrival of autumn, the behaviors change, we live in a closed environment, a recovery of the viral circulation is therefore possible.

Should we fear a new wave?

In the coming weeks, two scenarios are possible: a small wave of the delta variant, with an impact contained on the care system, or a significant increase in viral traffic, but without major impact on the care system . I am therefore optimistic enough, even if we can totally exclude the occurrence of a new variant. On the condition of preserving barrier gestures, we should be able to face a recovery.

In the medium term, the virus could become endemic, even seasonal, at a time because the Delta variant is contained by the vaccine and because its ability to evolve is limited. The other possibility is the emergence of an even more transmissible variant or that would escape the immunity conferred by the vaccine. In the long term, obviously, the crisis is not over.

When can we lower the guard?

The Government has chosen a gradual relief of restriction measures – a breakdown stop in some places – from November 15 rather than right now, it is the scenario we recommend. We keep two weaknesses: in France, the vaccination of the over 80 years remains to be improved [it is 86.4% for the first dose], and there is probably a loss of vaccination efficiency after six months at the most 65 years old. This is why vaccination with a third dose must accelerate, it has for the moment affected only 35% of the over 65 years eligible six months after the last dose.

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/Media reports.