Breakthrough Clinical Results
Valneva announced that the European Medicines Agency (EMA) has lifted the temporary restriction on using its single-dose chikungunya vaccine, IXCHIQ®, in individuals aged 65 and older. The EMA's safety committee (PRAC) conducted a thorough review following reports of serious side effects, primarily in elderly patients with multiple underlying conditions. While the vaccine remains contraindicated for those with weakened immune systems, the EMA concluded that IXCHIQ®'s benefits outweigh the risks for all age groups when a significant risk of chikungunya infection exists. The EMA noted the vaccine's effectiveness in producing antibodies against the virus, particularly beneficial for older adults at higher risk of severe disease. IXCHIQ® received EU authorization in June 2024 and a label extension for adolescents in March 2025.
Key Highlights
- EMA lifts temporary restriction on Valneva's IXCHIQ® chikungunya vaccine for use in people aged 65 and older.
- The decision follows a review by the EMA's safety committee (PRAC) of serious side effects, mainly in elderly patients with multiple underlying conditions.
- IXCHIQ® is now recommended for use in all age groups when there is a significant risk of chikungunya infection, after careful consideration of benefits and risks.
- The vaccine remains contraindicated for individuals with weakened immune systems.
Incidence and Prevalence
Global Epidemiology of Chikungunya Virus Infection
Incidence and Prevalence Estimates
The incidence of Chikungunya in Indonesia has been documented to range between 0.16-36.2 cases per 100,000 person-year according to a 2019 systematic review. In the same region, the median seroprevalence of anti-CHIKV IgM antibodies was 13.3%, with higher rates of 17.7% observed during outbreak scenarios compared to 7.3% in non-outbreak settings. For IgG antibodies, the median seroprevalence in Indonesia was 18.5% (range 0.0-73.1%) across both outbreak and non-outbreak settings.
In East Africa, a 2024 systematic review and meta-analysis revealed an overall pooled prevalence of chikungunya of 20.6% (95% CI: 18.8%-22.5%). Significant regional variations exist, with Rwanda and Djibouti exhibiting particularly high prevalence rates of 63.0% and 50.4% respectively, while Kenya and Somalia reported a moderate prevalence of 12.2%.
A 2024 seroprevalence survey conducted in Dire Dawa city, eastern Ethiopia found a high IgG seroprevalence for CHIKV of 44%, with less than 20% IgM seropositivity.
In southern Thailand, among 1466 febrile individuals studied, 398 (27.1%) had molecular or serological evidence of acute CHIKV infection. The proportions varied by year, with highest rates during epidemic periods (41.1% in 2018-2019, compared to 19.3% in 2012-2017).
A 2018 scoping review highlighted the heterogeneity of arboviruses seroprevalence between continents and within countries for Chikungunya virus, ranging from 0 to 76%.
Geographic Distribution and Regional Patterns
In Zambia, a sero-prevalence study in Lukanga swamps in 2016 found 36.9% (95% CI 30.5-43.8) of participants were sero-positive for Chikungunya, with those involved in fishing activities at greater risk.
Pakistan experienced a CHIKV outbreak in 2016-2017, with samples collected from 1,549 infected patients. Phylogenetic analysis showed Pakistani CHIKV strains belonged to Indian Ocean Lineage (IOL) of genotype ECSA and C1.3a clade.
In coastal Kenya, alphavirus exposure was common with ongoing interepidemic transmission of both ONNV and CHIKV, with women and adults more likely to be seropositive.
In Bandung, Indonesia, a study identified 135 (7.1%) CHIKV infections among non-dengue febrile illness patients, providing an incidence rate of 10.1/1,000 person years. Infections were identified year-round with increases during the rainy season (January to March).
In the United States, the CDC reported 171 travel-associated cases of Chikungunya in 2019. By October 2020, this number had decreased to 17 travel-associated cases across six states including California, Illinois, Missouri, North Carolina, Tennessee and Texas.
Current Trends and Outbreak Patterns
Massive nationwide outbreaks in Indonesia were reported during 2009-2010 with a total of 137,655 cases.
In Brazil, analysis of 608,388 cases of chikungunya showed that the disease demonstrated a decreasing trend of 13%, whereas clusters showed an increasing trend of 85%.
Since 2005, global Chikungunya outbreaks have occurred, inducing some fatalities and associated with severe and chronic morbidity. In late 2013, the first local transmission of Chikungunya was identified in Caribbean countries with subsequent spread throughout Central and South America.
In Madagascar, Aedes albopictus was found in 13 out of 15 sites sampled and has extended its geographical distribution, whereas Aedes aegypti has become rare. Six Ae. albopictus populations exhibited high dissemination infection rates for chikungunya virus ranging from 98 to 100%.
It's important to note that the true burden of chikungunya disease is most likely to be underestimated, particularly in developing countries, due to the lack of standard diagnostic assays and clinical manifestations overlapping with those of other endemic viral infections. This underreporting was specifically noted in Colombia, where the epidemiological surveillance system during the Chikungunya epidemic had low acceptability and flexibility.
Chikungunya is now considered an important re-emerging public health problem in both tropical and temperate countries, where the distribution of the Aedes mosquito vectors continues to expand.
Economic Burden
Economic Burden of Treating Chikungunya in USA and Europe
Based on recent publications, there is limited specific information about the precise economic burden of treating Chikungunya in the USA and Europe. However, available research provides some insights into the economic impact of this disease in these regions.
Presence in USA and Europe
A 2024 publication indicates that Chikungunya has been "acquired by international travelers in almost 100 destinations globally." More importantly, "viremic travellers with chikungunya infection have seeded chikungunya clusters (France, United States of America) and outbreaks (Italy in 2007 and 2017) in non-endemic countries where Ae. albopictus mosquitoes are present." This demonstrates that both the USA and Europe have experienced Chikungunya transmission.
General Economic Impact
According to a 2023 publication, "Reported costs associated with CHIKV diseases are substantial and vary by region, age group, and public/private delivery of healthcare services." The same source notes that "The chikungunya disease burden includes chronicity, severe infections, increased hospitalization risks, and associated mortality" and that "The disease can impact the economy in several spheres, significantly affecting the health system and national economies."
Comparative Data from Other Regions
While specific USA and European economic data is not detailed, studies from other regions provide context for potential economic impacts:
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A 2022 study from Brazil reported that in 2017, treatment of 2683 patients incurred an estimated cost of $383,514.40
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$174,322.91 (45.5%) were spent on emergency care
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$194,700.59 (50.8%) on hospitalizations
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The average cost of admissions was over $2400
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A 2018 study from Mexico estimated costs of disability due to chikungunya in the Instituto Mexicano del Seguro Social (IMSS) in Guerrero at 2,397,393.40 pesos
Indirect Economic Costs
The economic burden extends beyond direct medical costs. Chikungunya causes absenteeism and economic and social losses. In the Brazilian study: - 123 hospital professionals were infected with chikungunya - Sick leave duration ranged between 1 and 19 days - This generated 746 days of absence - The cost due to absenteeism was $14,490.90
Long-term Burden
The long-term economic impact is potentially significant as Chikungunya is characterized by an acute onset of fever with joint pain. While these symptoms generally resolve within 1-3 weeks, at least one-third of patients suffer from debilitating rheumatologic symptoms for months to years, which can contribute to substantial long-term economic burden through ongoing healthcare costs and lost productivity.
Despite documented outbreaks and clusters in the USA and Europe, current research does not provide specific recent estimates for the economic burden of treating Chikungunya in these regions.
Drug used in other indications
IXCHIQ® Clinical Indications Beyond Chikungunya
Based on the available information, there is no specific information about IXCHIQ® vaccine (also known as MV-CHIK or measles vector-based Chikungunya vaccine) being investigated for clinical indications besides Chikungunya virus infection.
The only confirmed information about IXCHIQ® is that it is the first licensed chikungunya vaccine approved by the: - US Food and Drug Administration in November 2023 - European Medicines Agency in May 2024 - Health Canada in June 2024
While there is mention of "a recombinant live attenuated measles virus-vectored vaccine" as one of two candidates that entered clinical phase II trials for Chikungunya, there is no information about this vaccine being investigated for other clinical indications.
None of the available information contains details about IXCHIQ®, MV-CHIK, or measles vector-based Chikungunya vaccine being tested for other clinical indications in any phase of clinical trials.