Key Points

• In Mayotte, flu outbreaks generally occur during the hot and humid season, between December and March.

• Surveillance confirms circulation of the influenza virus outside the typical seasonal pattern:

  • the virus began circulating in S09-2022, entered the epidemic phase in S18,

  • 106 positive samples for influenza virus since S09-2022, mostly type A (H1N1),

  • 124 emergency department visits since S09-2022 and 25 subsequent hospitalizations,

  • 2 severe cases hospitalized in intensive care since S17-2022.

• Specific context:

  • 2021-2022 Epidemic: From Week 42-2021 to Week 01-2022, circulation of viruses predominantly of type A (H3N2). Exit from the post-epidemic phase in Week 05-2022.

  • No influenza epidemic in 2020/2021: reduced immunity in the general population.

  • Co-circulation of SARS-CoV-2 with possible viral competition.