The Food and Drug Administration (FDA) has suspended the license for French drugmaker Valneva’s chikungunya vaccine, Ixchiq, effective immediately.

The FDA’s Center for Biologics Evaluation and Research (CBER) said the suspension was based on over 20 serious adverse events.

The serious adverse events included 21 hospitalizations and three deaths.

According to Reuters, one fatality was directly linked to vaccine-derived encephalitis.

“This vaccine was initially approved by FDA under the accelerated approval pathway in November of 2023 for the prevention of disease caused by the chikungunya virus (CHIKV) in individuals 18 years of age and older who are at increased risk of exposure to CHIKV,” the FDA stated.

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“CBER’s decision is based on serious safety concerns related to the vaccine, which appears to be causing chikungunya-like illness in vaccine recipients,” it added.

Reuters has more:

Valneva shares were down 22.1%, on track for their worst day since June 2022 and at the bottom of France’s index. U.S.-listed shares of the company were also down over 20% in early trading.

Valneva said it would immediately halt shipping and sales of the vaccine in the United States. The company is also evaluating the potential impact of permanently withdrawing the vaccine from the U.S. but would not change its financial outlook.

Ixchiq accounted for 7.5 million euros ($8.78 million), or more than 8% of Valneva’s total product sales, in the first half of 2025.

With the FDA suspending Ixchiq’s license, Bavarian Nordic’s Vimkunya is the sole remaining chikungunya vaccine available in U.S.

Vimkunya was approved by the FDA in April for protection among individuals aged 12 years and above.

“Furthermore, the clinical benefit of the vaccine has not yet been verified in confirmatory clinical studies. CBER’s benefit-risk analysis broadly shows the vaccine does not have benefits outweighing risks, under most plausible scenarios,” the FDA stated.

“For these reasons, CBER believes this vaccine is not safe and that continued administration to the public would pose a danger to health,” it added.

Further details from the FDA:

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On August 6, 2025, FDA lifted a pause in the use of Ixchiq in individuals 60 years of age and older and approved required updated labeling for Ixchiq, including revising the indication, and adding limitations of use and enhanced warnings and precautions to reflect serious postmarketing adverse reactions including hospitalizations and encephalitis in a person who died, with risk noted for individuals 65 years and older with chronic medical conditions.

On May 9, 2025, FDA issued a safety communication informing the public that the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) jointly recommended a pause in the use of Ixchiq (Chikungunya Vaccine, Live) in individuals 60 years of age and older while the Agencies undertook an investigation of postmarketing reports of serious adverse events, including neurologic and cardiac events, in individuals who have received the vaccine.

The November 9, 2023, approval of Ixchiq included a warning in the Prescribing Information informing that the vaccine may cause severe or prolonged chikungunya-like adverse reactions. Ixchiq contains a live, weakened version of the chikungunya virus and may cause symptoms in the vaccine recipient similar to those experienced by people who have chikungunya.

Ixchiq contains a live, weakened version of the chikungunya virus and may cause symptoms similar to those of chikungunya disease. Some of the postmarketing reports include adverse events that are consistent with severe complications of chikungunya disease, resulting in hospitalization; one person died from encephalitis.

 

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