The US Food and Drug Administration has approved Ixchiq (VLA1553), the first vaccine for chikungunya, a viral disease transmitted by the bite of infected Aedes aegypti mosquitoes. The vaccine, Ixchiq, was developed by French specialty vaccine company Valneva, located in Saint-Herblain. Infection with the chikungunya virus causes fever and severe joint pain that can persist for months or even years. It is an emerging global threat, with the highest risk of infection in Africa, Southeast Asia and parts of South America.
Ixchiq contains a live attenuated virus based on the La Réunion strain and is produced in Vero cells. To evaluate its effectiveness, two clinical trials were conducted in adults in the United States, as chikungunya outbreaks are unpredictable. Participants — 266 in the vaccine arm and 96 in the placebo arm — had immune responses measured; their antibody results were compared to levels shown to be protective in non-human primates. After a single dose of Ixchiq, 98.9% of participants had seroprotective levels of neutralizing antibodies, and 96.3% had neutralizing antibodies 6 months after vaccination. Previous safety analysis in over 3,000 people reported that 1.6% experienced vaccine-related serious adverse events. Common side effects were headache, fatigue, muscle pain, joint stiffness, fever and nausea. The FDA is requiring a post-marketing study of Ixchiq to determine the risk of severe chikungunya-like adverse reactions.
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