Where are we in 2025?

Retain – Where we 2025? new

• Chikungunya is a viral infection transmitted by mosquitoes Aedescausing fever and joint pain with persistent symptoms in more than a third of people, especially those over 65.
• In France, there is an epidemic recovery in Reunion and Mayotte and an already high number Aboriginal cases in mainland France.
• Two vaccines are authorized in Europe: IXCHIQ (alive attenuated) and Vimkunya (recombinant), but only 18–64 year olds are currently targeted.

Le chkwunka is a viral infection transmitted by mosquitoes of the genre Aedes and caused by the Chikv virus. Similarly, After an incubation of 3 to 7 days, the disease causes abrupt fever, joint and muscle pain.

About 30 to 40 % of patients present persistent symptomsincluding disabling chronic arthralgia beyond three months.

Age is the main gravity factor : The over 65s are the most exposed to severe and chronic forms.

Mortality Remains weak, especially affecting the elderly or with comorbidities.

In pregnant womenthe infection does not have a direct danger. but a transmission to the newborn is possible during childbirth that can lead to serious shapes of the newborn.

It is an infection that gives a sustainable immunity.

What are the recent epidemiological trends?

Chikungunya is a emerging threatfavored by climate change contributing to the expansion of vectors mosquitoes.

In France. after a major epidemic in Reunion between 2005 et 2007 (266,000 cases), where we 2025? new a new outbreak exceeds 54,000 cases to date and also reaches Mayotte with 969 cases.

In mainland France645 imported cases and 8 indigenous are identified, a record in number and precocity.

In the absence of viral treatment, what are the means of prevention?

Epidemiological surveillance is a key tool.

Public health France Coordinates epidemiological surveillance with a reinforced system in mainland France from May 1. to November 30 in the colonized areas by Aedes albopictus (« Tiger mosquito ) And specific overseas devices.

Any imported case Or indigenous must be declared, which triggers investigations and demustication operations. Prevention Based on the anti -actoral struggle (elimination of stagnant waters, repellents, mosquito nets).

Two vaccines are authorized in Europe, marking a new stage in where we 2025? new prevention.

The IXCHIQ vaccine (Valneva) refunded Since March 2025 has been available in France.

It has several key characteristics:

• Living attenuated vaccine, obtained by genetic engineering from an isolated strain in Reunion (2006).
• Indicated from 12 to 64 years.
• Single dose intramuscularly.
• Immunological efficiency:

• Seroconversion rate: 98.9 % in adults ≥ 18 years with protective antibodies 28 days after vaccination;

• Persistence of antibodies up to 2 years.

• Frequent side effects: headache, fatigue, myalgia, arthralgia, fever, nausea.
• Clinical efficiency (against infections, symptomatic forms, hospitalizations, deaths) not demonstrated.
• Constraints:
  • Contraindicated in immunocompromised people (alive vaccine attenuated).
  • Vaccination in pregnant women to consider on a case -by where we 2025? new -case basis, depending on the risk of exposure and gestational age.
  • Possible symptoms close to natural infection.
  • Protection after a period of 14 days involving the maintenance of measures to protect mosquitoes.

In the context of the epidemic in Reunion. the High Health Authority (HAS) published recommendations in March 2025 for the use of the IXCHIQ vaccine, targeting people aged 65 and over, in particular with comorbidities, 18–64 year olds with comorbidities and exposed professionals. After serious neurological effects reported in those over 65, This age group was excluded from the campaign on April 25.

The vaccine Vimkya (Bavarian Nordic) not reimbursed is also available.

He defines himself as:

• A recombinant vaccine based on pseudo-viral particles.
• Contains structural proteins E1, E2 where we 2025? new and capsidic of the virus.
• Indicated among 12 years old and over.
• A single intramuscular dose.
• Immunological efficiency:
  • In 12-64 year olds: 98 % seroconversion rate with protective antibodies 22 days after injection.
  • Among 65 and over: seroconversion rate of 87 %.
  • Persistence of antibodies up to 6 months.
• Frequent side effects: pain in injection, fatigue, headache, myalgia.
• No data on actual clinical efficiency yet

It does not present the constraints of a living vaccine attenuated as Ixchiq such as contraindication in immunocompromised people and development of undesirable effects close to a natural infection.

In a notice of June 6. 2025, You have does not recommend the use of the Vimkunya vaccine in Mayotte and Reunion, for lack where we 2025? new of sufficient data on its effectiveness and safety in vulnerable populations.