World's first chikungunya vaccine also authorised in Europe

This expands the fight against the infection caused by invasive mosquito species, which could rise in Europe as average temperatures rise.

Chikungunya cases are increasing dramatically

According to current data, a total of 64 chikungunya infections were reported in the EU/EEA member states in 2022, with a high number of unreported cases. In 2024, the number of chikungunya infections worldwide amounts to around 320000 CHIKVD cases. 120 of these were fatal. The disease, which is acute in most cases, can become chronic in some people and even result in multi-organ failure.1,2

Various factors could exacerbate the current situation. On the one hand, we live in an ageing society and, on the other, tropical infectious diseases could also become part of our everyday lives in this country as a result of climate change. Aedes aegypti is the main vector of the four viruses that have the greatest impact on human health: Yellow fever, dengue fever, chikungunya and Zika fever. If temperatures continue to rise in Europe, these four diseases could also become native to us.3,4

The transmission of the Chikungunya virus by tiger mosquitoes

The chikungunya virus (CHIKV) can be transmitted to humans by infected Aedes mosquitoes. The transmission is primarily from person to person. Unlike the mosquito species known to date, Aedes mosquitoes feed during daylight hours. They bite in the early morning and late afternoon. There are different Aedes mosquito species, with the Asian tiger mosquito (Ae. albopictus) being responsible for the majority of disease outbreaks.

However, the presence of the Asian tiger mosquito in Europe is not new: it was discovered in this country as early as 1979. The Asian tiger mosquito can be found in the Canary Islands, Madeira, Cyprus, southern Russia and Georgia. It is already known that climate change in recent years has led to the known vector of chikungunya and dengue viruses spreading to areas of Europe that were previously unaffected.5

An unpleasant "holiday souvenir"

Until now, the chikungunya virus has mainly been spread in Europe by travellers. The chikungunya virus can be accompanied by fever and joint pain when the disease occurs. Patients are often misdiagnosed as the symptoms overlap with other viral diseases. The overall burden of the disease and the associated socio-economic impact may still be underestimated.6

Serious chikungunya complications meet demographic change

Chikungunya can be acute (recovery in under 2 weeks) or chronic (weeks to years) and is associated with a high morbidity rate. The disease usually begins 4-8 days after the mosquito bite. Those affected suffer from acute onset of high fever and joint pain. Other symptoms include headaches and muscle aches, skin rashes, swollen ankles/wrists, nausea and fatigue. A severe course of the disease is characterised by neurological infections, pericarditis, hepatitis, severe skin rashes and multi-organ failure. For young children and elderly patients, these serious complications can be life-threatening.7,8

Seroprotective, neutralising antibody level against the chikungunya virus measurable after just 28 days

The chikungunya vaccine approval is based on the results of the double-blind, multicentre, randomised phase 3 study published in 2023 (DOI: 10.1016/S0140-6736(23)00641-4). This was conducted at a total of 43 vaccine study centres in the USA. Healthy volunteers aged ≥ 18 years took part in the study. Those with immune-mediated or chronic arthritis/arthralgia, a known or suspected immune system defect and a history of Chikungunya virus infection were excluded.

Study participants were randomised in a 3:1 ratio (VLA1553 or placebo). The primary endpoint was a positive chikungunya virus antibody level on day 28 after VLA1553 administration. A seroprotective, neutralising antibody level against the chikungunya virus was measured in almost 99% of the people in the VLA1553 group 28 days after VLA1553 administration. These results were independent of age. VLA1553 showed an adequate safety profile. The side effect profile was similar to that of other authorised vaccines. VLA1553 was equally well tolerated by both younger and older adults in the study.9

Advice for medical practice: vaccine protects before travelling

The world's first chikungunya vaccine has now also been authorised in Europe. Mosquito attacks by infected Aedes mosquitoes are still limited. But as the saying goes: better safe than sorry.10

Sources
  1. https://valneva.com/press-release/valneva-receives-marketing-authorization-in-europe-for-the-worlds-first-chikungunya-vaccine-ixchiq/?lang=de
  2. https://www.ecdc.europa.eu/en/chikungunya-monthly
  3. https://de.statista.com/statistik/daten/studie/1295906/umfrage/chikungunya-fallzahl-in-europa/
  4. Souza-Neto JA, Powell JR, Bonizzoni M. Aedes aegypti vector competence studies: A review. Infect Genet Evol. 2019 Jan;67:191-209. 
  5. Miranda MÁ. et al. (2022). AIMSurv: First pan-European harmonized surveillance of Aedes invasive mosquito species of relevance for human vector-borne diseases. GigaByte. 2022 May 31;2022:gigabyte57.
  6. Kam YW. Et al. (2015). Sero-prevalence and cross-reactivity of chikungunya virus specific anti-E2EP3 antibodies in arbovirus-infected patients. PLoS Negl Trop Dis. 2015 Jan 8;9(1):e3445.
  7. Burt FJ. et al. (2017). Chikungunya virus: an update on the biology and pathogenesis of this emerging pathogen. Lancet Infect Dis. 2017 Apr;17(4):e107-e117.
  8. https://climate-adapt.eea.europa.eu/en/observatory/evidence/health-effects/vector-borne-diseases/chikungunya-factsheet
  9. Schneider M. et al. (2023). Safety and immunogenicity of a single-shot live-attenuated chikungunya vaccine: a double-blind, multicentre, randomised, placebo-controlled, phase 3 trial. Lancet. 2023 Jun 24;401(10394):2138-2147. 
  10. https://valneva.com/press-release/valneva-receives-marketing-authorization-in-europe-for-the-worlds-first-chikungunya-vaccine-ixchiq/