FDA, CDC Recommend Pause on Valneva's Chikungunya Vaccine for Seniors
The decision follows ongoing investigations into serious adverse events primarily reported in elderly individuals who received the Ixchiq chikungunya vaccine.
Image Credit: Adobe Stock Images/Drobot Dean
The FDA and the Centers for Disease Control and Prevention (CDC) have jointly recommended pausing the use of Valneva’s chikungunya vaccine Ixchiq in the United States amid ongoing investigations into serious adverse events (SAEs). To date, these SAEs have primarily been reported in individuals over 65 years of age with underlying medical conditions or concomitant medications.
According to Valneva, the decision follows precautionary guidance from the Advisory Committee on Immunization Practices and a temporary suspension by the EMA in the same age group.1,2
“We reiterate our support for the precautionary measures that have been taken as well as our commitment to continue monitoring all reported serious adverse events, particularly from the active chikungunya vaccination campaign in La Réunion, as there have not been any further SAEs reported outside of this public vaccination effort to combat this ongoing outbreak,” said Juan Carlos Jaramillo, MD, chief medical officer, Valneva, in a press release. “We will continue engaging proactively with the global regulatory authorities while these important investigations continue over the coming months”.
According to the FDA, 17 SAEs have been reported, which included two deaths, in individuals between 62 and 89 years of age who received Ixchiq post-approval as of May 7, 2025, and included both neurologic and cardiac complications. Notably, six cases were reported in the United States. The SAEs, which were reported to the Vaccine Adverse Event Reporting System (VAERS), were not necessarily causally linked to vaccination and have resembled severe complications of natural chikungunya infection, including encephalitis.2
Ixchiq was first granted accelerated approval by the FDA in November 2023, based on results from two North American clinical studies in 3,500 individuals over 18 years of age with an increased risk of exposure to the virus. In the trial, Ixchiq demonstrated a 98.9% seroresponse rate at 28 days following a single immunization. Six months after vaccination, there was a 96.3% seroresponse rate.2,3
Although not commonly reported in clinical trials, 1.6% of vaccine recipients experienced severe or prolonged chikungunya-like reactions that interfered with daily activities or required medical intervention. Two individuals were hospitalized, and some experienced symptoms lasting at least 30 days post-vaccination. The FDA-approved Prescribing Information includes a warning regarding the potential for severe or prolonged chikungunya-like adverse reactions.2
According to the CDC, chikungunya was rarely found in US travelers before 2006. Between 2006 and 2013, a total of 28 cases per year were reported in US citizens who recently returned from affected areas in Asia, Africa, or the Indian Ocean. Local transmission was eventually identified in Florida, Texas, Puerto Rico, and the US Virgin Islands. However, local transmission hasn’t been reported since 2019. In 2024, a total of 199 cases were reported in US citizens who had traveled abroad, up from 154 in 2023.4 Annually, an estimated 60 million residents of the United States travel to countries in which mosquito-borne diseases such as chikungunya are endemic.3
Looking ahead, the FDA will conduct an updated benefit-risk assessment for individuals 60 years of age and older. Additionally, both agencies will continue evaluating postmarketing data, with the pause expected to remain in effect until the safety review is complete.2 At this time, the single-dose, live-attenuated vaccine remains recommended for use in individuals between 18 and 60 years of age in the United States, while the EMA and France’s Haute Autorité de Santé continue to support its use in individuals aged 12 to 64 years.1
References
1. Valneva Provides Update on Recommended Use of IXCHIQ® by Elderly Individuals in the United States. Valneva. May 12, 2025. Accessed May 13, 2025. https://valneva.com/press-release/valneva-provides-update-on-recommended-use-of-ixchiq-by-elderly-individuals-in-the-united-states/
2. FDA and CDC Recommend Pause in Use of Ixchiq (Chikungunya Vaccine, Live) in Individuals 60 Years of Age and Older While Postmarketing Safety Reports are Investigated. FDA. May 9, 2025. Accessed May 13, 2025. https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/fda-and-cdc-recommend-pause-use-ixchiq-chikungunya-vaccine-live-individuals-60-years-age-and-older
3. FDA Approves First and Only Vaccine for Chikungunya Virus Prevention. PharmExec. November 10, 2023. Accessed May 13, 2025. https://www.pharmexec.com/view/fda-approves-first-and-only-vaccine-for-chikungunya-virus-prevention
4. Chikungunya in the United States. CDC. Accessed May 13, 2025. https://www.cdc.gov/chikungunya/data-maps/chikungunya-us.html
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