Should we really fear a fifth wave of Covid-19 this fall? – Evening edition Ouest-France – 09/07/2021 – Ouest-France

A new study by the Institut Pasteur published on September 6, 2021 tends to show that the current vaccination in France would not be sufficient to avoid a fifth wave of Covid-19 contamination. Decryption with infectious disease specialist Matthieu Revest and virologist Yannick Simonin.

The epidemic of Covid-19 is it finally under control? According to Public Health France, the number of patients affected by the virus and hospitalized remains below the 11,000 patient mark since last Thursday. Good news to qualify, however, with this study published on September 6, 2021 by the Institut Pasteur. Thanks to new data on the Delta variant and the progress of the vaccine strategy, scientists were able to model what the fight against the epidemic might look like in the coming months.

What does this study say?

Epidemiologists from the Institut Pasteur warn of the risk, still present, of a fifth wave of Covid-19 contamination if nothing is done. The scientists started from an initial premise where the rate of reproduction of the virus, that is to say the estimate of the average number of people that a patient infects, is five. Last June, a previous study by the Institut Pasteur counted a reproduction rate of just four.

# COVID19 : epidemiology of #variant delta in a partially vaccinated population and implications for the control of a fall rebound. https://t.co/iFEi722dk8

– INSTITUT PASTEUR (@institutpasteur) September 6, 2021

On this basis, to avoid a new wave of contamination “95% of over 60s should be fully vaccinated, 90% of 19-59 year olds and 70% of adolescents”, according to the study. Figures not yet reached, since for the moment, only 88% of over 60 years, 81% of 19-59 years and 64% of adolescents are vaccinated.

The Institut Pasteur also warns: vaccination should not be synonymous with slackening of behavior. “With the Delta variant, vaccinated people are less well protected against infection, even if the protection remains very high against severe forms”, remind epidemiologists.

“We would expect roughly half of infections to occur in people who have been vaccinated (compared to this group representing over 70% of the population). It is therefore important that vaccinated people continue to respect barrier gestures and wear a mask to protect themselves from infection and avoid infecting their loved ones. “

What lessons can be drawn from this study?

For the virologist Yannick Simonin, lecturer at the University of Montpellier (Hérault), the message of this study is clear: “If we relax completely, in terms of vaccination, barrier gestures such as wearing a mask, washing hands and health passes, in fact, we could be faced with a fifth wave, he explains to us. It could potentially be of the same magnitude or even larger than previous waves. “

Matthieu Revest, infectious disease specialist at the Pontchaillou University Hospital Center, in Rennes (Ille-et-Vilaine), adds: “If there is a way to guard against a fifth wave: it is vaccination and the continuation of barrier gestures. “

If a fifth wave of contamination is envisaged in the fall, will it mean the return of the curfew or even confinement? Yannick Simonin is optimistic: “Thanks to vaccination and the maintenance of social distancing measures, we should normally avoid measures such as containment curfews”, believes the specialist in emerging diseases

According to him, the Institut Pasteur study can be read in two ways: “There is the pessimistic reading: we are still obliged to maintain restrictions such as the wearing of masks and the medical pass as well as distancing. But there is also a v More positive ision: if we apply these measures in addition to vaccination coverage, we should escape a possible new confinement. “

“Vaccinate the most widely”

But the virologist wants to be cautious and recalls that when it comes to coronavirus nothing is written in stone: “The study by the Institut Pasteur is a model. She gives a possible scenario but there is nothing for sure. It is very difficult to model. We must not take this as a script written in advance ”, underlines Yannick Simonin.

“We are in uncertainty, abounds Matthieu Revest. All hypotheses are possible and there is a very important possible field. What we know for sure is that the only way to stop the epidemic the most is to vaccinate as widely as possible. The more we vaccinate, the less the virus circulates. “