Five things to know about the JN.1, the majority variant in France

Last December, the World Health Organization (WHO) classified a new type, JN.1, also called Juno, as “ Variety of Interests ». Its rapid spread is particularly responsible for an outbreak of the epidemic that hit France and other European countries during the year-end holidays.

Juno will also represent the largest pandemic outbreak since the appearance of the Omicron, which peaked in late 2021-early 2022. In a report published last week and updated on Monday 15 January, Public Health France confirms that this is the case. France now has a majority.

► Low risk to public health…

Although the rise in cases linked to the JN.1 variant worries some doctors and scientists, the WHO has assessed “weak” The threat to public health posed by this new variant.

“While JN.1 infections are increasing rapidly and possibly increasing cases, the limited evidence available does not indicate that the associated disease severity is greater than that of other circulating variants. »The World Organization estimates.

For Gilbert Grubb, director of the Microbiology Institute at the Vaud University Hospital Center in Lausanne, Juno “false impression of severity” because “we now almost exclusively test symptomatic and hospitalized people to guide isolation measures”.

►… but the very contagious kind

As of early December, the JN.1 variant accounted for only 30% of reported Covid cases and in France, it was in the majority only in Ile-de-France. But the virus has managed to spread quickly because it is “Vaccines in 2021 and Omicron in early 2022 able to prevent neutralizing antibodies developed by the population due to infection”, A Swiss expert confirms.

The neutralizing capacity of antibodies is similar “A reduction of about 20 times” Underlines the expert, “due to change” New type and especially “S protein” or spike protein, Gilbert mentions Grebe. It is specifically these proteins that allow the virus to enter the body and that vaccines target.

► A descendant of the Omicron family

There is also JN.1 “Very similar to the BA.2.86 variant, of which it is a descendant” The professor explains. The BA.2.86 variant was placed under surveillance by the WHO last September.

“BA.2.86 is itself a distant descendant of BA.2, one of the five large early groups of omicrons, which appeared as early as 2022”The virologist continues.

► It moves better in winter

The increase in Covid cases in the JN.1 variant is due to several factors, especially climate. “It’s very cold and so people prefer to take the bus instead of walking, and public transport is a crowded place” Recalls the director of the Institute of Microbiology. This also causes cold, dry air “Dryness in Mucous Membranes”, Hence greater susceptibility to viruses.

In addition, other germs spread: “Co-infection can worsen the clinical picture” And we can “Wrongly believing that all cases are linked to Covid, when there is a strong mycoplasma epidemic, and Chlamydia pneumoniae Circulating from October-November. Expert estimates. Influenza and respiratory syncytial virus (RSV) also circulate.

► Possible new feature

According to the British health agency NHS, the Juno variant also causes diarrhea, a new symptom unique to it. In addition to this symptom, it will cause nausea and vomiting.

Cases of diarrhea associated with Juno variant contamination appear to be on the rise. “No reliable data allow us to support that diarrhea is such a symptom”, The American School of Public Health Johns Hopkins Bloomberg, an American institute, assured in a press release.