US Suspends Approval of Chikungunya Vaccine Ixchiq Due to Serious Side Effects

The United States health authorities have immediately suspended the license for the Ixchiq vaccine against chikungunya virus following reports of severe adverse effects. The vaccine, developed by the French pharmaceutical company Valneva and approved by the FDA in 2023, is one of only two vaccines authorized for use against this mosquito-borne disease in the U.S.

Recently, Valneva disclosed that four additional cases of serious side effects have been identified, including three involving individuals aged 70 to 82. These reports prompted the FDA to halt further distribution of Ixchiq, citing safety concerns. The suspension is effective immediately.

Chikungunya is transmitted primarily in tropical and subtropical regions, but recent outbreaks have been reported across various countries worldwide. The virus causes symptoms that closely resemble those of dengue fever and Zika virus, which include high fever, debilitating joint pain, and rash. While mortality from chikungunya is rare, elderly populations and infants are at increased risk of severe complications.

French company Valneva stated that it remains committed to the global health benefits of their vaccine, emphasizing ongoing evaluation of the situation. The company reported that Ixchiq generated €7.5 million (approximately $8.8 million) in sales during the first half of 2025. Following the announcement, Valneva's stock price dropped over 26% in early trading on the Paris stock exchange.

Public health experts warn that chikungunya could pose an escalating pandemic threat as climate change expands the range of mosquitoes capable of transmitting the virus. The World Health Organization recently issued a warning about the potential for a major chikungunya epidemic, noting early signs similar to outbreaks two decades ago that affected millions across the Indian Ocean and globally.

This development underscores the importance of ongoing monitoring of vaccine safety and highlights the need for effective prevention strategies against emerging viral threats.

Source: https://medicalxpress.com/news/2025-08-chikungunya-vaccine-ixchiq-side-effects.html