Launch of an investigation into chikungunya exposure in Réunion

cp_enquete_chik_reunion_20250820.pdf

Published on 20 August 2025

Press Contacts

Santé publique France
presse@santepubliquefrance.fr

ARS La Réunion
ars-reunion-communication@ars.sante.fr

Nearly 20 years after the historic 2005–2006 outbreak, Réunion experienced a second major wave of chikungunya in 2025. In light of this, Santé publique France and the Réunion Regional Health Agency are launching a joint survey to estimate the proportion of the population that has been infected. This seroprevalence study (antibody screening), led by Santé publique France, will measure the level of herd immunity against chikungunya and help better anticipate the risks of resurgence in the coming years.

An island-wide assessment of immunity

The study will begin on August 25, 2025, and will continue for three months. It aims to measure the seroprevalence of chikungunya across Réunion and by district.

The results will make it possible to:

Document the current level of immunity in the population of Réunion
Estimate the scale of the 2025 epidemic
Refine the analysis of the risk of an epidemic occurring in the coming years.

For the ARS Réunion, this data will be essential for:

Adapt prevention and communication strategies
Strengthen epidemiological surveillance
Optimize vector control measures.

A simple and reliable method

During the study’s recruitment period, individuals visiting a clinical laboratory for a previously scheduled test will be offered this analysis. It is open to all residents of Réunion, regardless of age or gender, who are invited to participate in this study during a blood draw at one of the 23 partner clinical laboratories.

Whether or not there is a known history of chikungunya, every participation is essential: the higher the number of participants, the more accurate and representative the results will be of the level of herd immunity.

After the prescribed tests are performed on the blood sample, the remaining serum (the liquid portion of the blood sample), if sufficient, will be used to test for the presence of chikungunya antibodies by the National Reference Center (CNR) for arboviruses, located at the University Hospital of Réunion.

In total, nearly 1,500 people will be included, with a balanced distribution across the island’s four districts, to ensure reliable and representative results for the entire population of Réunion, as well as estimates for each district. Each patient included in the study will receive the results of their test and will then know their immunity status regarding chikungunya.

A network of deeply committed partners

The island’s private laboratories and the National Reference Center for Arboviruses (University Hospital of Réunion) are fully committed to informing the public at partner testing sites and supporting patients throughout the study.