The United States has suspended the license for Ixchiq, a vaccine developed to fight the chikungunya virus, after new cases of severe side effects were reported.
Valneva, the French company behind the vaccine, said the FDA made the decision last Friday.
The move followed four fresh cases of adverse reactions.
Three of the patients were between 70 and 82 years old.
An 82-year-old was hospitalized for two days but was later discharged. The fourth case involved a 55-year-old.
Ixchiq is one of only two vaccines approved by the FDA to protect against chikungunya. The disease spreads through mosquito bites and is common in tropical and subtropical regions.
In recent years, however, the virus has spread worldwide.
Valneva received US approval for Ixchiq in 2023.
But health regulators in the US and Europe began reviewing safety concerns earlier this year, especially for older people.
Despite the US chikungunya vaccine suspension, Valneva insists it remains committed to global access.
Chief Executive Thomas Lingelbach said the company will continue to supply Ixchiq to countries where it is licensed.
He added that the firm will also work with partners to ensure low- and middle-income countries can access the vaccine during outbreaks.
The company said it is still calculating the financial impact of the suspension. Ixchiq brought in €7.5 million ($8.8 million) in sales during the first half of 2025.
However, the news caused Valneva’s shares to fall by more than 26% on the Paris stock exchange.
Valneva explained that the reported side effects were consistent with those already observed in trials and post-marketing studies.
Elderly patients remain the most vulnerable.
Chikungunya causes fever, joint pain, muscle aches, headaches, nausea, fatigue, and skin rashes. While it rarely causes death, the virus can be especially dangerous for babies and the elderly.
Experts warn it could become a future pandemic as climate change expands mosquito habitats.
In July, the World Health Organization warned of a potential large-scale outbreak, noting similarities to the 2004 Indian Ocean epidemic that infected nearly half a million people. Europe has already recorded 27 outbreaks this year, the highest number ever.
Kenya has also reported cases. The Kenya Medical Research Institute confirmed 25 positive cases in Mombasa County out of 45 suspected infections.
Valneva said it will continue to investigate the new cases and cooperate with health authorities. The company stressed that safety and global vaccine access remain its top priorities.
