EMA Expedites Adolescent Chikungunya Vaccine Recommendation

In its first meeting of 2025, the European Medicines Agency (EMA) Committee for Medicinal Products for Human Use (CHMP) gave the green light for the first vaccine in the EU to protect adolescents from the age of 12 years and up against the viral disease chikungunya.

The review of the vaccine, called Vimkunya, was expedited under the EMA’s accelerated assessment program because it is considered to be of major public health interest, the agency said in a press release today.

Chikungunya, also called CHIK fever, is a viral disease caused by the chikungunya virus (CHIKV), transmitted to humans by infected mosquitoes, primarily Aedes aegypti and Aedes albopictus. When an uninfected mosquito feeds on a person who has CHIKV circulating in their blood, the mosquito can ingest the virus, which then replicates and can be transmitted into a new human host, who can further infect other mosquitoes and perpetuate the transmission cycle. 

The vaccine — which is also intended for adults — is an adjuvanted recombinant vaccine containing CHIKV-like particles adsorbed on aluminum hydroxide. The virus-like particles consist of CHIKV capsid protein and envelope proteins derived from CHIKV Senegal strain 37997. Given as a single dose, it triggers the production of neutralizing antibodies at 22 days and up to 183 days post-vaccination. 

Disease Outbreaks More Frequent and Widespread

The disease was first identified in the United Republic of Tanzania in 1952, and the name chikungunya derives from a word in the Kimakonde language meaning “to become contorted”. CHIKV has now been identified in more than 110 countries in Asia, Africa, Europe, and the Americas. 

Since 2004, outbreaks of CHIKV have become more frequent and widespread. This has been partly due to viral adaptations allowing the virus to spread more easily via Aedes albopictus mosquitoes. Transmission often persists in countries where large parts of the population have not yet been infected.

In 2024, approximately 480,000 cases of chikungunya and more than 200 deaths were reported worldwide. CHIKV infections affect people mostly in the tropics and subtropics.

Countries reporting the highest number of cases are Brazil, Paraguay, Argentina, and Bolivia. Chikungunya is not endemic in Europe, with the majority of EU cases involving travelers who were infected elsewhere. However, in 2024, one locally acquired CHIKV case was reported in mainland Europe by France. Spread of the mosquito due to climate change could lead to cases of chikungunya in regions so far spared, warned the EMA. 

No Antiviral Treatment

CHIKV disease onset is typically 4-8 days after the bite of an infected mosquito and is characterized by abrupt fever onset that is frequently accompanied by severe joint pain. Other common signs and symptoms include joint swelling, muscle pain, headache, nausea, fatigue, and rash. The disease can be difficult to diagnose as its symptoms overlap with other infections, including those of dengue and Zika viruses. Most patients recover within a week, but some develop joint pain for several months or longer, and a small proportion of patients may develop severe acute disease, which can lead to multiorgan failure.

There is no specific antiviral drug treatment for CHIKV infections. Clinical management includes treatment of fever and joint pain, sufficient fluid intake, and rest. Most patients recover fully from the infection, however occasional cases of eye, heart, and neurological complications have been reported. 

The CHMP said that its opinion regarding the granting of a marketing authorization was largely based on data from two placebo-controlled studies. One study assessed the immunogenicity and safety of the vaccine in 3258 individuals from 12 to 64 years of age, and the other in 413 older adults. The immune response was evaluated in 3355 participants: 2748 with Vimkunya and 607 with placebo. Eight days after vaccination, the difference in sero-response rates (SRRs) between those vaccinated with Vimkunya and those with placebo in the first study was 46.1%. This rose to 96% at day 15, 96.6% at day 22, and 84% at day 183. In the second study, the difference in SRRs was 79.5% at day 15, 86.2% at day 22, and 74.4% at day 183.

The CHMP has requested a post-authorization efficacy study to confirm the effectiveness of Vimkunya in preventing chikungunya in adolescents and adults. The 

vaccine is expected to launch in Europe later this year.

In May last year, the EMA recommended granting a marketing authorization in the EU for Ixchiq, the first vaccine in the EU to protect adults 18 years and older against chikungunya. 

Dr Rob Hicks is a retired NHS doctor. A well-known TV and radio broadcaster, he has written three books and has regularly contributed to national newspapers, magazines, and online. He is based in the UK.