Key Points

Influenza

• 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 flu virus:

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

  • Rise in syndromic surveillance indicators and occurrence of 3 severe cases in intensive care

  • Transition to the pre-epidemic phase in S40-2021

• Special context for the 2021/2022 epidemic season:

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

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

  • Post-epidemic phase of bronchiolitis (RSV), whose epidemic was delayed by 2–3 months in 2021

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

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