Question asked by Thomas, on January 13
The frantic rate of contamination linked to omicron and the lesser danger of this new variant could open a way out of the health crisis. The European Medicines Agency (EMA) estimated at a press conference on Tuesday that we were heading “towards an endemization of the virus”, before recalling that Sars-CoV-2 “still behaves like a pandemic virus and the omicron emergency clearly shows this”.
“We should not forget that we are still in a pandemic. Nevertheless, with the increase in immunity in the population – and with omicron there will be a lot of natural immunity in addition to vaccination – we will quickly move towards a scenario closer to endemicity”, continued Marco Cavaleri, the head of vaccine strategy at the EMA.
This idea is not new, since already in May 2020, the World Health Organization indicated that “this virus could become endemic in our communities, [et] never disappear”. At the time, when the hope of an eradication of the virus still seemed possible, the news had not been relayed with enthusiasm in the media.
Permanent and stable circulation
What is an endemic? First of all, the term endemic makes it possible to “to designate a space for the dissemination of a virus, explains virologist Bruno Lina. It is a virus that is permanent resident of a geographical area or a given population, like dengue in traffic areas where mosquitoes are carriers.
In the scientific literature, this expression also describes a permanent and stable circulation. She “refers to a virus whose presence is relatively constant in a population with broadly predictable patterns and with a stable group of infected hosts capable of transmitting it to others”, adds the European Medicines Agency. Corn “This endemicity can be accompanied by epidemic outbreaks, which for respiratory viruses readily takes on a seasonal character when cooler temperatures are favorable to the circulation of viruses”, observes Arnaud Fontanet, professor at the Institut Pasteur. Thus, an endemic disease can also cause an epidemic to emerge during a given period, as in the case of the flu or the common cold.
In these situations, we can then speak of an endemo-epidemic disease. This is one of the hypotheses mentioned for Sars-Cov-2, as in Spain where the health authorities are preparing a Covid management plan similar to that of other winter respiratory diseases. Note that the adjective endemic characterizes the mode of circulation of a disease and not its severity. Thus potentially fatal diseases (AIDS, tuberculosis, malaria) are considered endemic in certain regions of the world.
“Analogy with the Russian flu”
However, according to the analysis of the scientists interviewed, the endemization of Sars-Cov-2 could be accompanied by a decrease in its severity. “This permanent circulation of the virus means that our immunity is regularly stimulated and strengthens with each encounter with the virus. In fact, the clinical manifestations of the disease become less severe over time in people who are increasingly better protected. develops Arnaud Fontanet.
A booster dose of vaccine would then only be necessary for the most fragile people, in the fall, before the circulation of the virus accelerates. “We can make the analogy with the OC43 virus [présumé responsable selon certaines études d’une très grave épidémie, aussi appelée grippe russe, ndlr] which emerged at the end of the 19th century. One hundred and twenty years later, this virus which gives a mild infection is still present. Eventually, Sars-CoV-2 may do the same,” analyzes Bruno Lina. Provided, in particular, that no new variant appears “very different from the previous ones which could temporarily call into question this balance being installed due to a very pronounced virulence and immune escape capacity”, says Arnaud Fontanet.