Chikungunya is a mosquito-borne viral disease caused by chikungunya virus, transmitted primarily by Aedes aegypti and Aedes albopictus mosquitoes. The disease is characterized by sudden onset of fever and often severe, debilitating joint pain. Other symptoms may include joint swelling, muscle pain, headache, nausea, fatigue and rash. Although most patients recover, joint pain and other symptoms may persist in some patients for months or years, resulting in substantial morbidity and disability. Severe disease and deaths are uncommon but can occur, particularly among newborns and older adults with underlying medical conditions. There is currently no specific antiviral treatment for chikungunya.

Two chikungunya vaccines have received regulatory approval in several countries: IXCHIQ, a live-attenuated vaccine, and VIMKUNYA, a recombinant virus-like particle vaccine. Both are authorized for use in individuals aged 12 years and older by various regulatory authorities. However, regulatory status and recommendations differ between countries. Post-marketing safety concerns have led to restrictions and regulatory actions affecting IXCHIQ, particularly concerning its use in older adults and people with underlying medical conditions, including suspension of its licence in the United States and withdrawal of its marketing authorization in the United Kingdom.

The unpredictable occurrence of chikungunya outbreaks presents challenges for conducting randomized clinical efficacy trials. Initial regulatory approvals have therefore been based on vaccine-induced neutralizing antibody responses, using immunological thresholds considered predictive of protection, rather than demonstrated clinical efficacy. Post-licensure studies are needed to assess vaccine effectiveness, duration of protection and safety in different populations.

WHO, with its Strategic Advisory Group of Experts on Immunization (SAGE), is reviewing the available evidence on chikungunya vaccines, including their safety, immunogenicity, effectiveness and potential public health use, to inform global vaccination policy recommendations.