Key Points

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

• This year, surveillance data confirm relatively early circulation of the influenza virus:

  • 139 samples positive for influenza virus since August 2021, mostly type A(H3N2)

  • Significant increase in surveillance indicators over the past few weeks

  • Three severe cases requiring intensive care in week 37

  • Transition to the epidemic phase in week 42 of 2021

• Special context for the 2021/2022 epidemic season:

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

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

• Enhanced surveillance since September 17 (syndromic and virological surveillance)

• Start of the flu vaccination campaign on September 16, 2021, in Mayotte