Surveillance for adverse events following use of live attenuated chikungunya vaccine, United States, 2024, and the associated public health response in 2024 and 2025

Euro Surveill. 2025 Aug;30(32):2500543. doi: 10.2807/1560-7917.ES.2025.30.32.2500543.

Abstract

A live attenuated chikungunya vaccine (IXCHIQ) received licensure in the United States (US) for ≥ 18-year-olds in November 2023. Post-licensure safety surveillance identified 28 adverse events in 2024 among US persons, including six neurological or cardiac serious adverse events (SAEs) in males ≥ 65 years. In early 2025, providers were alerted, a precaution for older persons was issued and vaccine guidance was updated. In May, following 11 additional SAEs reported outside the US, use in older persons was temporarily paused until 6 August 2025.

Keywords: adverse event; chikungunya; immunisation; ixchiq; live attenuated; serious; vaccine.

MeSH terms

  • Adolescent
  • Adult
  • Adverse Drug Reaction Reporting Systems*
  • Aged
  • Aged, 80 and over
  • Chikungunya Fever* / prevention & control
  • Chikungunya virus* / immunology
  • Drug-Related Side Effects and Adverse Reactions* / epidemiology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Population Surveillance
  • Product Surveillance, Postmarketing*
  • Public Health
  • United States / epidemiology
  • Vaccines, Attenuated / administration & dosage
  • Vaccines, Attenuated / adverse effects
  • Viral Vaccines* / administration & dosage
  • Viral Vaccines* / adverse effects
  • Young Adult

Substances

  • Vaccines, Attenuated
  • Viral Vaccines