Independent report

Chikungunya vaccine in UK travellers: JCVI advice

Published 16 July 2025

Background and epidemiology

Chikungunya virus (CHIKV) causes an infection predominantly spread to humans through the bite of infected Aedes mosquitoes. These mosquitoes are typically active during the daytime (in particular after sunrise and at dusk). Chikungunya virus typically circulates in tropical and subtropical regions of the world, in areas of Asia, Africa, Latin America and the Caribbean where the Aedes mosquitoes have a wide distribution. In recent years, these mosquitoes have also been found in parts of Europe (France, Italy and Spain) and the United States.

In recent decades, following international spread of disease, large outbreaks have occurred in:

• the Indian Ocean islands
• India
• the Pacific islands
• the Caribbean
• Central America
• South America

A notable outbreak occurred in La Réunion in 2025. Smaller outbreaks have occurred in France and Italy. The presence of Aedes mosquitoes in European countries, and importations from infected travellers returning from endemic countries, means that the likelihood of CHIKV spreading in mainland Europe is high.

Chikungunya symptoms include:

• fever of abrupt onset
• severe joint pains (known as arthralgia)
• muscle pains (known as myalgia)
• headaches
• sensitivity to light (known as photophobia)
• skin rashes

The illness is usually self-limiting and symptoms usually improve within one to 2 weeks, but joint pains can be severe and may persist for months or years. Chikungunya is an unpleasant disease which only rarely results in death.  However, chronic disability rates can be high^{[footnote 1]}.

Individuals at risk of more severe disease include those over the age of 65 years, individuals with immunosuppression, and newborn babies.

There is currently no chikungunya transmission in the UK, with all identified cases being related to travel and having been imported into the UK.

Vaccines

Currently there are 2 chikungunya vaccine products which are licensed for use in the UK, IXCHIQ® and Vimkunya®.

IXCHIQ® (marketing authorisation holder Valneva) is a single-dose live attenuated vaccine. It was initially licensed by the Medicines and Healthcare products Regulatory Agency (MHRA) in February 2025 for individuals aged 18 years and over. As this is a live attenuated vaccine, it is contraindicated in individuals who are immunosuppressed. Information presented to the travel sub-committee on 27 February 2025 noted that clinical trials had demonstrated 98.9% seroresponse (based on detection of neutralising antibodies) one month after vaccination, with 96.6% after 3 years^{[footnote 2]}. Those over 65 years of age showed similar responses to younger adults in the trial. Data on the use of this vaccine in pregnancy remains very limited.

Vimkunya® (marketing authorisation holder Bavarian Nordic) is a non-replicating virus-like particle (VLP) vaccine. It was approved by the MHRA in May 2025 for use in individuals ages 12 years and over. Data from clinical trials was presented to the travel sub-committee showing a 98% seroresponse (based on detection of neutralising antibodies) in individuals aged 12 to 64 years 22 days after vaccination, falling to 86% seroresponse at 6 months^{[footnote 3]}. In adults over 65 years of age, a seroresponse of 87% 22 days after vaccination was observed, reduced to 76% at 6 months^{[footnote 4]}. Similarly to IXCHIQ®, there was a noted lack of data in pregnancy.

Safety signal

Following the travel sub-committee meeting held on 27 February 2025, as a result of international use of the IXCHIQ® live attenuated vaccine in the East African outbreak, a safety signal was identified of serious adverse events in older people. 

In April 2025, following the reporting of 3 serious adverse events including one fatality following the use of IXCHIQ® in a campaign on the island of La Réunion, the French National Authority for Health (Haute Autorité de santé, or HAS) has temporarily suspended vaccination in individuals aged 65 years and above in La Réunion and Mayotte (viewed on 7 July 2025), pending acquisition of additional data.

In May 2025, the United States Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) recommended a pause of the use of IXCHIQ® in individuals aged 60 years and over. This was based on assessment of globally reported adverse events including some which occurred in the United States.

Also in May, the European Medicines Agency announced a temporary restriction in the use of IXCHIQ® in individuals aged 65 years and over, and reported that the European Medicines Agency’s (EMA) safety committee Pharmacovigilance Risk Assessment Committee (PRAC) had started a review (reference 8). In July, following completion of its review, PRAC announced that the previous temporary restriction on the use of IXCHIQ® in individuals aged 65 years and over should be lifted. PRAC concluded that the vaccine should only be given when there is a significant risk of chikungunya infection and after careful consideration of the risks and benefits of vaccination PRAC concluded that the vaccine should only be given when there is a significant risk of chikungunya infection.

The Joint Committee on Vaccination and Immunisation (JCVI) met to discuss their advice on the use of chikungunya vaccine as a travel vaccine on 4 June 2025. Since the JCVI committee meeting, the MHRA has published advice announcing a temporary suspension in the use of IXCHIQ® chikungunya vaccine in individuals aged 65 years and over. This temporary restriction was recommended by the Commission on Human Medicines and is a precautionary measure while the MHRA conducts a safety review. This recommendation was based on the global safety signal as there are currently no UK cases. JCVI may consider further advice following the completion of MHRA’s safety review.

Global data available at this time has highlighted 23 cases of serious adverse reactions including 2 with a fatal outcome. The vast majority of these serious cases were reported in individuals aged 65 years and over (age range between 62 and 89 years of age). HAS and the FDA and CDC note that some of the post-marketing safety reports include adverse events which are consistent with severe complications of chikungunya disease including neurological and cardiac events.

UK-based healthcare professionals, patients and care givers can report suspected adverse reactions following vaccination to the MHRA using the Yellow Card scheme.

Advice

The travel sub-committee of JCVI met to discuss advice for the use of chikungunya vaccines (IXCHIQ® and Vimkunya®) in UK travellers in addition to standard bite avoidance measures.

Chikungunya vaccine may be considered for:

• those travelling to regions with active CHIKV outbreaks
• long term or frequent travellers to regions with CHIKV transmission in the past 5 years
• laboratory staff working with CHIKV

When vaccination is considered to be indicated, JCVI advises that:

• Vimkunya® vaccine may be offered to individuals aged 12 years old and over
• IXCHIQ® vaccine may be offered to immunocompetent individuals aged 18 to 59 years old

The current advice against the use of IXCHIQ® live attenuated chikungunya vaccine in adults aged 60 years and older is precautionary and will be reviewed when further safety data is available.

This cautious approach was based on the report of an individual aged 62 years experiencing serious adverse effects, and an opportunity to align operationally with current advice on caution on the use of yellow fever vaccine in individuals aged 60 years and older. To further align the yellow fever vaccine and IXCHIQ® advice, JCVI also advises that the IXCHIQ® vaccine should not be offered to individuals with a history of thymus disorder or thymectomy.

Currently there is no evidence of a safety signal with the use of Vimkunya® in older adults. Given the safety signal has only been associated with the live-attenuated vaccine and the nature of the adverse events reported, the committee did not consider it necessary to restrict the use of the VLP product (Vimkunya®) at this time, but note that this vaccine has not been used extensively.

References

1. Kang H and others. ‘Chikungunya seroprevalence, force of infection, and prevalence of chronic disability after infection in endemic and epidemic settings: a systematic review, meta-analysis, and modelling study’ Lancet Infectious Diseases 2024: volume 24, issue 5, pages 488 to 503 ↩

2. Schneider M and others. ‘Safety and immunogenicity of a single-shot live-attenuated chikungunya vaccine: a double-blind, multicentre, randomised, placebo-controlled, phase 3 trial’ The Lancet 2023: volume 401, issue 10394, pages 2138 to 2147 ↩

3. Richardson JS and others. ‘Chikungunya virus virus-like particle vaccine safety and immunogenicity in adolescents and adults in the USA: a phase 3, randomised, double-blind, placebo-controlled trial’ The Lancet 2025: volume 405, issue 10487, pages 1343 to 1352 ↩

4. Tindale LC and others. ‘Chikungunya virus virus-like particle vaccine safety and immunogenicity in adults older than 65 years: a phase 3, randomised, double-blind, placebo-controlled trial’ The Lancet 2025: volume 405, issue 10487, pages 1353 to 1361 ↩