COVID-19. Infinite variations and waves? We asked the experts

COVID-19.  Infinite variations and waves?  We asked the experts

First wave, second wave, third wave… soon the eighth? Since March 2020, we have been facing a repeat of the Covid-19 epidemic waves. And just like the regular increases in the number of cases, the variants (Alpha Delta, Omicron…), as well as the sub-variants follow one another.

Although the virus is better controlled thanks to natural immunity and various vaccination campaigns, this succession of waves and variants seems endless. So, will we face endless waves and new variants? explanations.

A new wave every four or six months?

Sure french culture, the professor and infectologist at Bordeaux University Hospital, Denis Malvy, drew a parallel, on August 19, 2022, between the reappearance of waves of Covid-19 and the end of immunity produced by vaccines. “The SARS-Cov2 virus produces variants and subvariants at a rate of six to four months. This appearance is related to the fact that vaccination protects for a relatively short period of time.” He explained. That is, after these four to six months after vaccination, the population would be less immunized and therefore more receptive to the transmission of the virus.

For Pascal Crépey, professor-researcher of epidemiology and biostatistics at the Rennes School of Higher Studies in Public Health, successive epidemic outbreaks are not only linked to the loss of immunity but are also determined by the appearance of new variants and by the weather conditions. more or less favorable to transmission.

It is the combination of these three factors that triggers the epidemic waves. “The Delta variant was at the origin of the fourth wave in the summer of 2021, but it could also cause the fifth thanks to the winter”, he raises AND acquired immunity against one variant does not always have a determining effect against another: “The Omicron variant came at the tail end of Delta’s winter surge, when the population was immune enough to stop Delta’s growth.” he explains. In short, epidemic waves continue to be complex phenomena in which all the variables are not under the control of specialists.

Also read: COVID-19. Eighth wave, new variant? These are the four scenarios for back to school

A virus that will become seasonal and not serious?

How long will we have big waves? “The bottom line is whether there will be new and very different variants of Omicron,” answers Yves Buisson, epidemiologist and president of the Covid cell of the National Academy of Medicine. a stage “who would shuffle the cards”, but currently it is unlikely, virological surveillance does not show this trend. “If we continue like this, we will have tails and we will probably end up reaching an epidemic that will resemble that of the flu, with outbreaks in winter”.

Pascal Crépey judges that Covid-19 will be considered a simple virus when it ceases to be a public health problem, “That is, when will we have the means to treat it effectively so that we no longer have severe forms: this requires effective treatments and routine vaccination”.

What about the new vaccines at the beginning of the school year, which the laboratories promote as more specific and therefore more effective against the virus? “We were disappointed in the duration of protection conferred by vaccines against infection,” acknowledges Pascal Crepey. “If new vaccines that combine different strains make it difficult for the virus to find escape routes, the situation can only get better”.

Also read: COVID-19. Will the fourth dose of the vaccine be available to everyone in the fall?

Unequal management of the pandemic at the global level?

Would the zero Covid policy adopted by some countries, particularly in Asia, delay the end of the epidemic globally? This is what the epidemiologist Yves Buisson thinks.

“In China, the population does not develop hybrid immunity because the authorities do not allow people to get infected, so there is no natural immunity,” he lets go “These are populations that are very poorly immunized and in which the virus can recover the hairs of the beast and relaunch the epidemic throughout the world,” continues, lashing out at the lack of homogeneity in the fight against Covid on a global level. “The entire world population must acquire herd immunity to regulate the circulation of the virus”.

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