FDA Suspends Approval of Live-Attenuated Chikungunya Vaccine Ixchiq

The U.S. Food and Drug Administration (FDA) has suspended the biologics license for the live-attenuated chikungunya vaccine, Ixchiq, in response to reports of serious side effects in older adults. The FDA granted accelerated approval of Ixchiq in November 2023 to prevent chikungunya virus in adults 18 years and older with an increased risk for exposure. However, recent adverse event reports have raised concerns about the vaccine's safety. The FDA has determined that the vaccine's clinical benefit remains unproven, its risks outweigh potential benefits in most scenarios, and continued use would endanger public health.

Key Takeaways:

• The FDA has suspended the biologics license for Ixchiq due to reports of serious side effects in older adults, including one confirmed encephalitis death, more than 20 serious adverse events resembling chikungunya illness, 21 hospitalizations, and three deaths in total.
• The FDA's Center for Biologics Evaluation and Research has determined that the vaccine's clinical benefit remains unproven and its risks outweigh potential benefits in most scenarios.
• Valneva, the manufacturer of Ixchiq, maintains that the reported cases align with known trial and postmarketing data, especially in older adults already flagged in prescribing warnings.
• The company is investigating further and may take additional action regarding the FDA decision.
• Valneva will immediately stop shipping and selling the vaccine in the United States.
• The FDA granted accelerated approval of Ixchiq in November 2023 to prevent chikungunya virus in adults 18 years and older with an increased risk for exposure.
• Chikungunya virus is a mosquito-borne disease causing fever, rash, headache, nausea, fatigue, and severe joint and muscle pain, which can be long-lasting and debilitating.

Statistics:

• 1 death confirmed as encephalitis
• 21 hospitalizations
• 3 deaths in total
• More than 20 serious adverse events resembling chikungunya illness
• The FDA Vaccine Adverse Event Reporting System
• 2023, the year the FDA granted accelerated approval of Ixchiq
• 18 years, the minimum age for adults to receive the vaccine
• November, the month the FDA granted accelerated approval

Sources:

• "FDA Takes New Steps to Protect Public Health from Riskier Chikungunya Vaccine" HealthDay News (Aug. 25, 2025)
• Valneva, manufacturer of Ixchiq
• U.S. Food and Drug Administration