The U.S. Food and Drug Administration (FDA) has suspended the biologics license for Ixchiq, a live-attenuated chikungunya vaccine, following reports of severe adverse reactions in older adults that mirrored symptoms of the mosquito-borne virus itself.
Chikungunya is transmitted by infected mosquitoes and causes fever, rash, headache, nausea, fatigue, and often debilitating joint and muscle pain that can persist for months or years.
Ixchiq received accelerated FDA approval in November 2023 for adults aged 18 and older at increased risk of exposure. But recent data from the FDA’s Vaccine Adverse Event Reporting System has raised safety concerns. Reports include one confirmed death from encephalitis, three deaths overall, more than 20 severe adverse events resembling chikungunya illness, and 21 hospitalizations.
The FDA’s Center for Biologics Evaluation and Research concluded the vaccine’s benefits have not been clearly demonstrated, while risks outweigh potential advantages in most cases. Regulators said continued use could pose a threat to public health.
Valneva, the vaccine’s manufacturer, acknowledged the adverse cases but noted they are consistent with known trial and postmarketing data, particularly among older patients already highlighted in prescribing warnings. The company said it is conducting further investigations and may respond formally to the FDA’s action.
“As we determine potential next steps, and as the threat of chikungunya escalates globally, Valneva remains committed to maintaining access to our vaccine as a global health tool,” said Thomas Lingelbach, Valneva’s chief executive officer. “We aim to continue supplying Ixchiq in countries where it is licensed and to work with partners to expand vaccine access in low- and middle-income endemic regions.”
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