Data is pointing to a slight rebound. Since mid-May, the Covid-19 virus seems to have been circulating more actively in France and the rest of Europe. Various indicators point in this direction: Emergency room visits for suspected Covid-19 cases are up across all age groups (+ 19%), and SOS Médecins procedures for the same reasons are also up (+ 29%), with a higher share of activity than observed in 2023 and 2021 during the same period. Numbers were even higher (+ 52% and + 51% respectively) the previous week.
Wastewater monitoring, now carried out by the Sum'Eau network, also shows an increase in viral circulation in the 12 stations monitored nationwide. This is especially the case in the southernmost French region of Occitanie, at the Toulouse and Lescar stations. According to laboratory sequencing data, viral circulation is also high in the Île-de-France region.
Population behavior
This impressionistic view of the situation – the only one possible since the end of the SI-Dep platform (for "screening information system") in June 2023 and the pause in surveillance of acute respiratory infections from April to October – does not allow us to assess a precise incidence but shows a clear upward trend compared with previous weeks. The same is true at the European level, where the European Centre for Disease Prevention and Control (ECDC) stated in its June 14 bulletin that "following a period of very low activity, there is evidence of increased SARS-CoV-2 activity for some reporting countries."
What can this flare-up be attributed to? As with every wave, the behavior of the population, as well as the weather conditions, must be taken into account. In the spring, many Taylor Swift fans reported on social media that they had tested positive after attending one of the American singer's concerts. It is quite possible that these events, from May 9 to 12 in Paris and June 2 and 3 in Lyon, constituted clusters, as has often been the case in previous epidemic rebounds.
But this rise in cases also and above all, corresponds to the rise of a new sub-variant in both France and many other countries: the KP.2 sublineage, an offshoot of the JN.1 variant that had accompanied the peak of contaminations in winter 2023-2024. In France, KP.2 now represents 24% of sequences, according to the risk analysis published on June 10 by French Public Health and the National Reference Center (CNR) for Respiratory Infections.
Faster reinfection
Like other JN.1 sub-variants, KP.2 is characterized by two mutations in the spike protein on its envelope: substitutions F456L and R346T. "These lead to immune evasion from a number of pre-existing neutralizing antibodies. This means that the virus is able to reinfect more easily people who have already been infected and are potentially immunized by older viruses," explained Bruno Lina, director of the CNR for Respiratory Infections in Lyon. This combination is nicknamed "FLiRT," after the letters in the technical names of the mutations (F, L, R, T).
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