661 outbreaks: New Swine Flu Strain Evades Immune System

In France, the number of swine flu outbreaks has sharply increased. According to the French authority ANSES, a total of 661 cases were registered in the first year after the appearance of the new virus genotype H1N2#E – significantly more than the average of 400 cases per year previously.

The reason for this surge, according to ANSES, is the virus's ability to bypass the immunity built up through previous infections and vaccinations.

The new genotype first appeared in Brittany in 2020 and spread across mainland France, displacing existing strains. Scientists analyzed samples from 2019 to 2022 to better understand the origin and rapid spread of the virus.

The analysis revealed that the new pathogen differs significantly from previous viruses. It can bypass existing immunity in pig herds. Affected animals suffer from high fever, respiratory problems, coughing, and increased miscarriages in sows. ANSES states that the new virus genotype most likely originated from Denmark. It likely entered French herds through the importation of infected animals, either directly or through other European countries. The origin was determined through genetic comparisons with other known swine flu viruses.

There is also concern about the potential risk to other animal species and humans. Since 2020, infections with H1N2#E have been observed on turkey farms, and in 2021, a severe case occurred in a human. ANSES therefore warns of a possible exchange of viruses between swine, poultry, and human flu viruses, which could lead to new pathogens adapted to humans. Pigs are considered potential "mixing vessels" for such viruses – a scenario that also played a role in the 2009 flu pandemic. The French authority emphasizes the importance of strict biosecurity measures in pig farms. These include quarantine rules for newly housed animals and consistent monitoring for flu symptoms. However, there is currently no legal requirement in France to report swine flu cases.