The U.S. Food and Drug Administration has suspended the biologics licence for Valneva’s chikungunya vaccine, Ixchiq, citing four additional serious adverse events that resembled chikungunya-like illness in recipients. Three of the cases involved adults aged 70 to 82, while the fourth concerned a 55-year-old, according to the French drugmaker. The regulator’s order, which takes effect immediately, halts all shipments and sales of Ixchiq in the United States. Approved in late 2023, Ixchiq is the first preventive vaccine for the mosquito-borne virus and is also authorised in Europe, Canada, the United Kingdom and Brazil. The product contributed €7.5 million (about US$8.8 million) in the first half of 2025, or a little over 8 % of Valneva’s product revenue. Valneva said it is reviewing the cases and potential next steps but has not changed its full-year guidance. Investors responded swiftly: the company’s Paris-listed shares fell roughly 25 % to around €3.71, their steepest one-day drop since listing.