FDA Update on the Safety of Ixchiq (Chikungunya Vaccine, Live)
Audience: Patient, Health Care Professional, Pharmacy, Cardiology, Neurology, Internal Medicine, Family Practice, Travel Clinics
August 22, 2025 -- Today the US FDA’s Center for Biologics Evaluation and Research has suspended the biologics license for Valneva Austria GmbH’s live-attenuated Ixchiq vaccine. This vaccine was initially approved by the 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.
CBER’s decision is based on serious safety concerns related to the vaccine, which appears to be causing chikungunya-like illness in vaccine recipients. There has been one death from encephalitis directly attributable to the vaccine (CSF PCR was + for the vaccine strain of the virus) and over 20 reported serious adverse events that were consistent with chikungunya-like illness. Reported serious adverse events have included 21 hospitalizations and 3 deaths.
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. For these reasons, CBER believes this vaccine is not safe and that continued administration to the public would pose a danger to health.
August 6, 2025 -- 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.
At the time of the May 9, 2025, recommended pause, FDA conveyed its intention to conduct an updated benefit-risk assessment for the use of Ixchiq in individuals 60 years of age and older. FDA has completed an updated benefit-risk assessment of Ixchiq, including for use in individuals 18 years of age and older. Based on the available data, and its benefit-risk assessment, FDA has removed the recommended pause in the use of Ixchiq in individuals 60 years of age and older and has approved updates to the Prescribing Information and Patient Information that it required of the company, Valneva Austria GmbH.
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.
Key Points About the Required Labeling Updates
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The Indications and Usage statement has been revised from: Ixchiq is a vaccine indicated for the prevention of disease caused by chikungunya virus (CHIKV) in individuals 18 years of age and older who are at increased risk of exposure to CHIKV to: Ixchiq is a vaccine indicated for the prevention of disease caused by chikungunya virus (CHIKV) in individuals 18 years of age and older who are at high risk of exposure to CHIKV.
As part of the Indications and Usage section, Limitations of Use has been added that states: “Vaccination with Ixchiq is not advisable for most U.S. travelers. For most U.S. travelers, the risk of exposure to CHIKV is low. The Centers for Disease Control and Prevention provides resources for assessing likelihood of exposure to CHIKV among travelers and laboratory workers (Chikungunya Vaccine Information for Healthcare Providers).
The decision to administer Ixchiq should take into consideration an individual’s risk of severe or chronic disease outcomes if infected with CHIKV and risks of serious, severe, or prolonged chikungunya-like illness caused by vaccination with Ixchiq [see Warnings and Precautions (5.2) and Adverse Reactions (6.1 and 6.2)], in addition to the risk of exposure to CHIKV. For travelers, factors to consider include level of disease activity at destination, duration of travel or residence, and likelihood of exposure to mosquitoes.”
- The Warnings and Precautions section has been revised to reflect the serious adverse reactions that have been reported during postmarketing use with Ixchiq. Some of the postmarketing reports include adverse reactions that are consistent with severe complications of chikungunya, resulting in hospitalization, including encephalitis in a person who died. These reports suggest that individuals 65 years of age and older with one or more chronic medical conditions may have an increased risk for these serious adverse reactions following vaccination with Ixchiq.
- In the Adverse Reactions section, a new subsection, Postmarketing Experience, includes information about the adverse reactions that have been identified during postmarketing use with Ixchiq. These adverse reactions are consistent with serious chikungunya-like illness and include cardiac and neurological reactions.
Safety Monitoring Continues
With the November 9, 2023, approval of Ixchiq, FDA required the company to conduct a postmarketing study to assess the serious risk of severe chikungunya-like adverse reactions following administration of Ixchiq. The study is intended to be initiated by October 1, 2025.
Continuous monitoring and assessment of the safety of all vaccines remains an FDA priority. Suspected adverse events may be reported to the Vaccine Adverse Event Reporting System (VAERS), which is co-managed by FDA and CDC.
Source: FDA
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