Lyon, France, November 10, 2026
Valneva SE, a specialty vaccine company, has announced positive five-year antibody persistence results for its single-dose IXCHIQ® chikungunya vaccine, demonstrating that 94% of evaluated participants maintained a seroresponse five years after vaccination. The findings provide additional evidence of the vaccine’s long-term immunogenicity and support its potential value in preventing chikungunya, a mosquito-borne viral disease associated with fever, severe joint pain and other debilitating symptoms. The five-year results were obtained from the ongoing VLA1553-303 clinical follow-up study, which is monitoring antibody responses for up to ten years after a single vaccination. Among the 221 healthy adults evaluable at Year 5, 94% maintained neutralizing antibody levels above the established seroresponse threshold. Valneva also reported comparable antibody persistence in older adults aged 65 years and above and younger adults aged 18 to 64 years. The findings are consistent with earlier follow-up results and add to the growing clinical evidence supporting the durability of immune responses generated by IXCHIQ. The announcement highlights the importance of long-lasting immunity against chikungunya, particularly because outbreaks can be difficult to predict and vaccination opportunities may be limited in regions where the disease is endemic.
Five-Year Study Shows Sustained Antibody Persistence
The five-year findings come from the VLA1553-303 long-term antibody persistence study, which follows participants who previously received a single dose of IXCHIQ. At the Year 5 assessment, 221 healthy adults were evaluable for antibody persistence. According to Valneva, 94% maintained neutralizing antibody titres above the seroresponse threshold five years after vaccination. The threshold was defined as a neutralizing antibody titre of at least 150, measured using the micro plaque reduction neutralization test (µPRNT50). This measurement evaluates the ability of antibodies to neutralize the chikungunya virus in laboratory testing. The company also reported that antibody persistence was comparable between participants aged 65 years and older and those aged 18 to 64 years, with similar geometric mean titres and seroresponse rates. These results build on previously reported 12-month, 24-month, three-year and four-year antibody persistence findings. The sustained response is particularly relevant for a disease such as chikungunya, where exposure risk can vary geographically and outbreaks may occur unpredictably. However, antibody persistence is an immunological measure and should not be interpreted as direct proof of five-year clinical protection against infection. Further epidemiological and post-marketing effectiveness studies will help establish how these antibody responses translate into real-world protection.
IXCHIQ Supports Long-Term Chikungunya Prevention Research
IXCHIQ is Valneva’s single-dose live-attenuated chikungunya vaccine, developed to stimulate an immune response against the chikungunya virus. The disease is transmitted primarily through the bites of infected Aedes mosquitoes and can cause fever, severe joint and muscle pain, headache, nausea, fatigue and skin rash. In some affected individuals, joint pain can persist for months or even years, creating a substantial health burden. Chikungunya has been identified in more than 110 countries across Asia, Africa, Europe and the Americas. Its geographical spread and the expansion of mosquito populations have increased concerns about the public health impact of the infection. Valneva stated that the five-year antibody persistence findings reinforce the potential value of a single-dose vaccination strategy, particularly for travellers and populations living in endemic regions. The company also highlighted the importance of vaccine access in low- and middle-income countries, where healthcare infrastructure and vaccination availability may be more limited. The long-term follow-up study will continue monitoring participants for up to ten years after vaccination, providing further information about the durability of the immune response over time.
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Brazil Vaccination Campaign Strengthens Real-World Evidence
Alongside the long-term clinical follow-up, Valneva is generating additional evidence through post-marketing studies and real-world vaccination initiatives. One important initiative is a large-scale Pilot Vaccination Strategy in Brazil, conducted between February and October 2026 by the Brazilian Ministry of Health and Instituto Butantan, with support from Valneva. The campaign vaccinated nearly 80,000 adults aged 18 to 59 years, representing the first large-scale public vaccination campaign using IXCHIQ. The initiative is serving as a foundation for further post-marketing investigations designed to evaluate vaccine effectiveness and safety under real-world conditions. These studies are expected to complement the long-term antibody persistence findings and provide additional information about the vaccine’s public health value. The five-year results also received funding support through the Coalition for Epidemic Preparedness Innovations (CEPI) and the European Union’s Horizon Europe programme. Valneva continues to develop and commercialize vaccines targeting infectious diseases with significant unmet medical needs. The latest findings strengthen the clinical evidence for IXCHIQ’s sustained immunogenicity, while ongoing follow-up and real-world research will be important in understanding its longer-term effectiveness and safety across different populations.
Source: Valneva press release
