Immediate public health surveillance response to cyclone Chido, Mayotte, 14 December 2024.

On 14 December 2024, Cyclone Chido caused extensive damage to infrastructures in Mayotte, including water, electricity and communication networks. Health surveillance systems were no longer functional. Santé publique France provided health risk analyses to support local control measures. Malnutrition and dehydration, follow-up care, pregnancy and post-partum complications, mental health, gastrointestinal diseases, bacterial wound superinfections and bronchiolitis were the main risk identified. The preliminary ad hoc surveillance systems confirmed our analyses. We also present lessons learnt 1 month after the event.