As nearly 1,000 new cases of chikungunya and three new deaths have been confirmed in La Réunion between May 19 and May 25, 2025, the epidemic is showing signs of slowing down . The ARS (Regional Health Agency) of La Réunion confirms that “we expect a slowdown of the epidemic” and deem a resurgence next summer as “unlikely” (Illustrative photo www.imazpress.com).
The onset of the austral winter is expected to reduce mosquito activity, and thereby the transmission of the virus, notes the agency. Outbreaks of arboviral diseases , which are viral illnesses transmitted by mosquitoes, tend to decrease during the winter months.
The ARS plans to utilize this period to “implement social mobilization actions in collaboration with local services, associations, and the Rectorate.” Additionally, within educational institutions, information campaigns are scheduled until early July, and again at the start of the school year, aiming to raise student awareness about essential preventive behaviors to limit the transmission of vector-borne diseases, specifically dengue and chikungunya.
The reduction in the number of cases “will allow for a rapid and massive intervention strategy around newly reported cases to contain the virus’s spread as much as possible,” the agency indicates.
– A “unlikely” resurgence of the epidemic –
La Réunion experienced its first chikungunya epidemic in 2005, with a resurgence in 2006. However, the ARS considers the likelihood of a similar scenario occurring during the 2025/2026 season as “unlikely”.
“Approximately 200,000 individuals have retained immunity due to their exposure during the 2005/2006 outbreak. This year, around another 200,000 individuals have been affected,” the agency elaborates.
“This level of collective immunity should prevent the emergence of a new epidemic peak in 2025/2026,” the ARS claims. However, it is essential to exercise caution: the chikungunya virus may continue to circulate in the coming months at levels lower than previously observed, but still could pose a risk of severe disease for vulnerable individuals (adults with comorbidities, elderly individuals, newborns, and infants). This past summer’s epidemic was marked by the failure of the vaccination campaign against chikungunya.
Launched in early April, the initiative specifically targeted individuals over the age of 18 with comorbidities.
Senior individuals over 65 were eventually excluded on April 25 after three “serious adverse events,” including one death among individuals over 80 who were recently vaccinated.
The vaccine used, Ixchiq , developed by Valneva, is the first vaccine for chikungunya to receive marketing authorization in Europe .
– A poorly accepted vaccination campaign –
To date, more than 5,300 people have been vaccinated in La Réunion, far short of the 40,000 doses ordered for the island.
“As of May 26, 2025, 3,116 doses of vaccines were administered as part of the vaccination campaign,” the ARS details, adding that more than 1,000 beneficiaries received vaccines on medical prescription, as well as 1,201 doses provided to CHU personnel.
During a visit to La Réunion on April 23, Health Minister Yannick Neuder announced that he had “purchased all vaccine doses” against chikungunya for France.
“This additional order of 50,000 doses, accounting for the extension of vaccination to individuals aged 18 to 64, is now suspended due to the restrictions on vaccine use declared by HAS in its notice of April 25, 2025, which takes into account pharmacovigilance signals,” the ARS stated in a letter.
Since the beginning of the year, nearly 51,000 confirmed Indigenous chikungunya cases have been reported in La Réunion, according to data from Public Health France.
However, estimates made by the regional unit of Public Health France suggest around 200,000 individuals may have been potentially infected during the outbreak, the ARS highlights.
This estimate is based on a cross-analysis of the evolution of confirmed cases, data from sentinel physician activity, and information provided by the General Social Security Fund.
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