Can 40,000 Vaccinations Curtail France's Chikungunya Emergency

With 40,000 vaccines available, can the France's ARS Réunion stop the raging chikungunya epidemic on La Réunion island. Just last week, 4,913 cases of chikungunya were confirmed. 

Since the beginning of 2025, there have been 33,835 confirmed cases and six related fatalities.

In this French overseas department of 890,000 individuals, the first phase of the vaccination campaign commenced on April 7, 2025, with 40,000 doses of Valneva SE's IXCHIQ® vaccine. This effective vaccine is made freely available on Réunion.

Following the recommendations of the French health authorities, ARS Réunion has decided to extend access free vaccinations to the following groups who have not contracted chikungunya in the past:

Those aged 18 to 64 with comorbidities or chronic diseases, and,

Seniors aged 65 and over, whether or not they have comorbidities.

The purpose of the vaccination program is to protect vulnerable individuals at risk of developing severe complications from chikungunya in the absence of prior natural immunity.

What's unusual about this chikungunya epidemic is the virus's genotype.

Although Aedes aegypti mosquitoes generally transmit chikungunya virus (CHIKV), the ongoing outbreak on La Réunion Island was caused by Aedes albopictus, which acted as the primary vector due to the ECSA CHIKV genotype's adaptation to this vector, specifically the E1-A226V and E1-K211E mutations.

In 2004, these CHIKV mutations spread eastward from Africa to the Indian Ocean islands and India, resulting in outbreaks in various locations.

This may be the cause of the extensive increase in infectivity.

To alert international travelers to this serious health risk, France issued a Level 4 emergency for Réunion in March 2025, and the U.S. Centers for Disease Control and Prevention (CDC) issued a Level 2 Advisory on February 25, 2025, regarding the epidemic on La Réunion.

Since most cases in the U.S. are travel-related and virus testing is not offered everywhere, commercial lab testing services, such as UltaLabs, can detect chikungunya infections.

From a prevention perspective, the UK Travel Health Pro and the CDC advise travellers to ideally arrange an appointment with their healthcare professional at least four to six weeks before travel. Currently, there are no vaccine certificate requirements under the International Health Regulations.

As of April 18, 2025, about 800,000 IXCHIQ doses have been distributed worldwide.

In the U.S., chikungunya vaccination services are available at most travel clinics and pharmacies.