Valneva SE announced positive two-year antibody persistence and safety data for its single-dose, live-attenuated chikungunya virus vaccine (VLA1553) in adults aged 18 years and above. The data comes from the ongoing VLA1553-303 study, an open-label Phase 3b trial designed to evaluate the long-term immunogenicity and safety of the vaccine.
The VLA1553-303 trial enrolled 363 participants who had previously participated in the pivotal Phase 3 clinical trial VLA1553-301. The primary objective of the study is to evaluate the persistence of antibodies annually for up to 10 years after a single immunization with VLA1553. The secondary objective is to evaluate long-term safety through two years, including monitoring for new-onset serious adverse events and any ongoing adverse events of special interest from the VLA1553-301 trial.
Chikungunya: A Growing Global Threat
Chikungunya virus (CHIKV) is a mosquito-transmitted disease that poses a significant public health threat. The virus, transmitted by Aedes mosquitoes, can cause acute chikungunya, characterized by sudden onset of high fever and joint pain in approximately 75% of those infected. CHIKV outbreaks can be large and explosive, affecting a substantial portion of the population, and are difficult to predict.
Beyond the acute phase, chikungunya can lead to chronic incapacitation in a high proportion of patients, with symptoms lasting months to years. Studies have shown that a significant percentage of patients continue to experience disease effects more than two years post-infection. Chronic chikungunya can negatively impact quality of life, leading to persistent rheumatologic disease, long-term joint pain, and stiffness, affecting daily activities and mobility.
VLA1553: A First-in-Class Vaccine
VLA1553 is the world's first and only approved vaccine against chikungunya. Given the challenges of conducting classical efficacy studies for chikungunya vaccines due to unpredictable outbreaks, regulatory pathways, including the FDA's accelerated approval pathway, rely on serological endpoints. The FDA-agreed surrogate endpoint is the seroresponse rate, supported by evidence demonstrating that neutralizing antibodies confer sterilizing immunity in non-human primates.
Valneva is also pursuing label extensions for its chikungunya vaccine, Ixchiq®, with submissions to the EMA and Health Canada.
