The United States Food and Drug Administration (FDA) has suspended the licence of the IXCHIQ chikungunya vaccine after reports of 21 serious adverse events and three deaths, including one death directly linked to the vaccine. The vaccine, initially approved under the accelerated approval pathway in November 2023, was intended for adults travelling to outbreak areas and laboratory workers at risk of exposure. The FDA’s decision comes amid concerns that the clinical benefits of the vaccine have not yet been verified in confirmatory trials, and that continued use could pose a risk to public health.

Key Highlights:

Safety concerns and adverse events:

• Reports of hospitalisations due to cardiac and neurologic complications in older adults triggered a temporary pause in May 2025.

• The FDA suspension followed 21 chikungunya-like illness cases and three deaths, with one death showing cerebrospinal fluid positive for the vaccine strain.

• Clinical trials are yet to confirm the vaccine’s benefit-risk profile.

Vaccine details

• IXCHIQ uses a live, weakened virus to elicit an immune response.

• The other chikungunya vaccine, VIMKUNYA, uses virus-like particles and is approved for people over 12 years.

• Both vaccines are approved in several countries but are not yet widely distributed.

Global and Indian context

• WHO is reviewing vaccine trial and post-marketing data to provide recommendations based on global epidemiology.

• In India, chikungunya outbreaks continue, with 1,741 laboratory-confirmed cases and 30,876 suspected cases recorded until March 2025.

• Bharat Biotech is developing a three-dose chikungunya vaccine for India, administered on Days 1, 29, and 57.

Regulatory and public health implications

• The FDA states that under most plausible scenarios, benefits of IXCHIQ do not outweigh the risks.

• Authorities recommend suspending administration to prevent further serious health outcomes.

• Monitoring and evaluation continue for other vaccines in development and use globally.

The FDA’s suspension of the IXCHIQ vaccine underscores the importance of rigorous safety monitoring for new vaccines, particularly for viral diseases like chikungunya. Pharmacists and healthcare providers should stay informed about vaccine approvals, adverse event reports, and ongoing clinical trial results to ensure patient safety. India’s efforts to develop a locally tailored multi-dose vaccine highlight the ongoing need for safe and effective preventive measures against chikungunya.