Chikungunya Reunion: Ongoing Challenges and Response Dilemmas
- The 2025 Chikungunya epidemic in Reunion Island vividly demonstrated the speed and unpredictability of such outbreaks, complicating efforts to implement a timely and effective vaccination response.
- The arrival of the Valneva IXCHIQ® vaccine during the peak of the epidemic, or even too late as was the case, did not guarantee a meaningful impact due...
- Three weeks after the launch of the vaccine campaign using the Valneva IXCHIQ® vaccine in late April 2025, a safety signal emerged in elderly patients, including several serious...
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Chikungunya Epidemic in Reunion (2025): A Case Study in Vaccine Response Challenges
What Happened: The 2025 Chikungunya Outbreak in Reunion
The 2025 Chikungunya epidemic in Reunion Island vividly demonstrated the speed and unpredictability of such outbreaks, complicating efforts to implement a timely and effective vaccination response. The attack rate reached an estimated 43.35%,with several dozen deaths attributed to the virus,primarily among the elderly and newborns.
The arrival of the Valneva IXCHIQ® vaccine during the peak of the epidemic, or even too late as was the case, did not guarantee a meaningful impact due to a lack of proactive anticipation and integration into a extensive global strategy. The core issue highlighted was the critical importance of rapid implementation of vaccination recommendations, consistency between national and international guidelines, and clear interaction regarding the benefit/risk balance.
The Vaccine Rollout and safety Concerns
Three weeks after the launch of the vaccine campaign using the Valneva IXCHIQ® vaccine in late April 2025, a safety signal emerged in elderly patients, including several serious adverse events and one death (Mosnier et al. Ofid 2025). This prompted a rapid suspension of vaccination for individuals aged 65 and over.Despite this, the European Medicines Agency (EMA) continued to recommend the vaccine.
Moreover, another vaccine, Vimkunya® – a protein vaccine based on pseudo-viral particles developed by Bavarian Nordic - received it’s Marketing Authorization (AMM)
in Europe. (AMM: Administrative procedure which authorizes a pharmaceutical laboratory to market a molecule.)
Expert Perspective: ARS Reunion’s response
Professor Xavier Deparis, Director of Health Security at the ARS of Reunion, offered the following comment:
“I discover the article published on the HIV.org site about the vaccination campaign against chikungunya in Reunion. The article might suggest that at ARS Reunion, we could or could have or that we should have gone faster in the vaccination campaign: not so simple unfortunately. First of all, it should not be forgotten that the IXCHIQ® vaccine in Valneva had obtained the AMM of the European Medicines Agency in June 2024, subject to the continuation of additional studies of efficiency and safety. The ARS informed the DGS of the interest of a vaccine campaign without waiting for December 2024.Having authorization to have vaccines before the end of January 2025 may have made it possible to break the dynamics of the epidemic. The DGS asked for HAS at the end of December 2024, four months after the first cases of chikungunya. The HAS rendered its opinion according to an emergency referral procedure in early March 2025: too late to impact the dynamics of the epidemic. implementing the vaccine campaign in less than a month, between mid-March and early…”
Timeline of Events
| Date | Event |
|---|---|
| june 2024 | Valneva IXCHIQ® vaccine receives AMM from EMA (conditional on further studies). |
| december 2024 | ARS Reunion informs DGS of interest in a vaccine campaign. |
| End of December 2024 | DGS requests opinion from HAS. |
| Early March 2025 | HAS delivers opinion (deemed too
|