The US Food and Drug Administration (FDA) announced late last week that it has suspended the license for French drugmaker Valneva’s chikungunya vaccine, saying that continued administration of the vaccine to the public would pose a danger to health.
The FDA’s Center for Biologics Evaluation and Research (CBER) said the decision was based on serious safety concerns related to Ixchiq, a live-attenuated vaccine that was approved by the FDA in 2023. The move comes after the agency recommended a pause in the use of Ixchiq in people ages 60 and older on May 9 while officials investigated severe events in vaccine recipients. On August 6, the FDA lifted the pause but recommended the vaccine only for people at high risk of exposure to chikungunya virus, which is spread by Aedes mosquitoes.
Ixchiq contains a weakened form of the virus, which may cause symptoms of chikungunya disease. Before the suspension of the license, it was recommended for Americans traveling to areas where active chikungunya outbreaks are occurring.
In a news release, the FDA said there had been one death from encephalitis directly attributable to the vaccine, and over 20 reported serious adverse events that were consistent with chikungunya-like illness, with 21 hospitalizations and 3 deaths.
“Furthermore, the clinical benefit of the vaccine has not yet been verified in confirmatory clinical studies,” the agency said in a statement. “CBER’s benefit-risk analysis broadly shows the vaccine does not have benefits outweighing risks, under most plausible scenarios.”
Valneva’s response
Ixchiq is one of two vaccines on the market for the prevention of chikungunya, which has been reported in 119 countries and territories and is expected to expand with climate change as the territory for Aedes mosquitoes widens. In July, the World Health Organization warned that urgent action was needed to prevent the escalation of chikungunya outbreaks.
Valneva said the FDA’s decision to suspend the license for Ixchiq after lifting the pause on August 6 was based on updated data from the Vaccine Adverse Event Reporting System, which includes four additional serious adverse events that occurred outside the United States. The company said it believes all four newly reported cases, which occurred in three patients ages 70 to 82 and one 55-year-old, describe symptoms “consistent with those previously reported during clinical trials and post-marketing experience.”
“As we determine potential next steps, and as the clear threat of chikungunya continues to escalate globally, Valneva remains fully committed to maintaining access to our vaccine as a global health tool for addressing and preventing outbreaks of this devastating illness,” Valneva CEO Thomas Lingelbach said in a company press release.
Like the FDA, the European Medicines Agency also recommended a similar pause on Ixchiq in early May, placing a temporary restriction on vaccinating people aged 65 and older. But the EMA lifted its pause on July 25.