Covid-19: a study confirms the effectiveness of the vaccine booster to contain the hospitalizations of the 5th wave – LCI

How far will the 5th wave of Covid-19 go in France? This Monday, the Pasteur Institute presents a study on which the government of Jean Castex relied a few days earlier to justify the acceleration of the vaccination campaign, and in particular of the 3rd dose, in France.

The authors maintain that the booster dose could curb the epidemic in France. An assessment taken up by the Minister of Health Olivier Véran who announced last Thursday the opening of the vaccination booster to all French people over 18 years old, as early as 5 months after the first injections.

As with any estimate, scientists at the Institute put forward several scenarios, adding that they were based on “incomplete data and uncertain assumptions”. For their baseline scenario, the authors relied on a 10% transmission rate of the virus, estimating that “French people were going to strengthen their protective behavior in the face of the growing epidemic from November.” Among other things, respect for barrier gestures, wearing a mask, teleworking and reducing contact.

Scientists also assume that 400,000 booster doses will be given every day, and that 80% of those 50 and over and 50% of 18-49 years will adhere to this additional injection.

They finally retain the scientific consensus according to which the vaccine effectiveness would drop on average to 50% against the infection and to 85% that against the hospitalization, six months after the injection of the first two doses.

If nothing is done, “the peak of hospitalizations could reach 2250 hospitalizations per day“, explain the scientists on this basis. If the recall were only intended for the 65 years and over – with 80% of membership in this category -, this peak could be reduced by 20%. If the recall campaign were applied to the 50 years and older, with 80% membership in this category, the peak would be reduced by 33%.

Finally, the vaccination booster extended to all adults over 18 years old – a scenario adopted by the authorities in France – with 80% adherence among those over 50 and 50% adherence among those aged 18-49, the reduction of peak hospitalizations would wait 44%.

All these additional measures would therefore make it possible to limit the peak of this 5th wave to 1,250 hospitalizations per day. Enough to reduce the tensions that threaten hospital services in the months to come.

Be careful though. “If there is no reinforcement of protective behavior, the peak would remain around 2200 hospitalizations per day” and this, even if all adults have access to the booster dose, warns the study by the Institut Pasteur.

Important clarification: the Pasteur study does not include the perspective of the new Omicron variant. Discovered last week in South Africa, the latter has led several countries, including France, to close their borders to prevent the spread of the virus. This Monday, the WHO reported “no information to suggest that the symptoms associated with Omicron are different from those of other variants”, but recognizes an increase in “hospitalization rates in South Africa” since the arrival of the variant. The organization is still waiting “several days to several weeks to understand the level of severity”, she concludes in her note published on its site. The big question being that of the effectiveness of current vaccines on this variant.