U.S. and European authorities recommend pausing Ixchiq vaccine use in older adults

The U.S. Food and Drug Administration (FDA) and the US Centers for Disease Control and Prevention (CDC) are recommending that the administration of Ixchiq (chikungunya vaccine, live, attenuated) to individuals 60 years of age or older should be paused until postmarketing reports of serious adverse events, including neurologic and cardiac events, are investigated.1 The FDA plans to conduct an updated benefit–risk assessment for the use of Ixchiq in individuals 60 years of age or older. During the assessment process, the FDA and CDC are recommending a pause in use of the vaccine in this age group. Further updates will be available after the Ixchiq safety evaluation is completed.1 Similarly, the European Medicines Agency (EMA) has announced an in-depth safety review of Ixchiq. While the EMA review is underway, the EMA considers Ixchiq to be contraindicated in adults aged 65 years or older, but vaccination can continue in people under 65 years of age. The EMA acknowledges that clinical studies on Ixchiq mainly included people below 65 years of age and the vast majority of reported serious adverse effects have involved people 65 years of age or older.2 The EMA is also reminding healthcare professionals that Ixchiq must not be given to people with a weakened immune system due to disease or medical treatment, as these individuals are at greater risk of complications from vaccines containing live attenuated viruses, regardless of age. This would include patients with congenital immunodeficiency, hematological cancers and solid tumours, patients with HIV infection who are severely immunocompromised, and patients receiving chemotherapy or long-term immunosuppressive therapy.2 Ixchiq was approved in November 2023 in the United States, and in June 2024 in Canada and Europe, for the prevention of disease caused by chikungunya virus in individuals 18 years of age or older.1-3 Ixchiq contains a live, attenuated version of the chikungunya virus and may cause side effects similar to those of chikungunya disease.1 The vaccine is given as a single 0.5 mL dose intramuscularly.3 About 80,000 doses of Ixchiq have been distributed worldwide to date. As of May 7, 2025, 17 serious adverse events, including two deaths, had been reported in individuals 62–89 years of age who received Ixchiq globally. Most serious adverse events have occurred in individuals with underlying chronic medical conditions.1 One of the fatal cases involved an 84-year-old man who developed encephalitis. The second death occurred in a 77-year-old man with Parkinson's disease whose swallowing difficulty worsened and may have led to aspiration pneumonia.2 Some of the adverse events in postmarketing reports are consistent with severe complications of chikungunya disease, resulting in hospitalization. FDA-approved prescribing information includes a warning that the vaccine may cause severe or prolonged chikungunya-like adverse reactions. During clinical trials, severe chikungunya-like adverse reactions that prevented daily activity and/or required medical intervention occurred in 1.6% of Ixchiq recipients and none of the placebo recipients. Two recipients with severe chikungunya-like adverse reactions were hospitalized. Some recipients had prolonged chikungunya-like adverse reactions, lasting for at least 30 days.1Health Canada response On March 10, 2025, Health Canada acknowledged that reports of hospitalization for cardiac or neurologic events following vaccination with Ixchiq in persons 65 years of age or older are being investigated in the United States. Health Canada is monitoring Ixchiq safety and will take appropriate action if new safety information is identified that may affect the benefit–risk profile of the vaccine.4References:U.S. Food and Drug Administration. FDA and CDC recommend pause in use of Ixchiq (chikungunya vaccine, live) in individuals 60 years of age and older while postmarketing safety reports are investigated: FDA Safety Communication. May 12, 2025. (accessed May 22, 2025).European Medicines Agency. EMA starts review of Ixchiq (live attenuated chikungunya vaccine). May 7, 2025. (accessed May 22, 2025).Valneva Canada Inc. Ixchiq (chikungunya vaccine, live, attenuated) product monograph. Kirkland, QC; June 20, 2024. (accessed May 22, 2025).Government of Canada. For health professionals: chikungunya. March 10, 2025. (accessed May 22, 2025).

U.S. and European authorities recommend pausing Ixchiq vaccine use in older adults

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