Vaccine Candidate VLA1553 Highly Protective Against Chikungunya Virus

A single dose of VLA1553, a live-attenuated vaccine candidate for protection against Chikungunya virus infection, was found to be safe and highly immunogenic, according to research presented at the annual meeting of the American Society of Tropical Medicine and Hygiene, held from October 30 to November 3, 2022, in Seattle, Washington.¹

In a double-blinded, randomized, multicenter, pivotal phase 3 study (ClinicalTrials.gov Identifier: NCT04546724), researchers evaluated the immunogenicity and safety of VLA1553, a vaccine candidate manufactured by Valneva, for protection against Chikungunya virus infection. Healthy adult individuals (N=4115) were enrolled at 43 sites across the United States and randomly assigned in a 3:1 fashion to receive either a single dose of VLA1553 or placebo. The researchers evaluated the immunogenicity and safety of VLA1553 at day 28 following vaccination. The study volunteers were observed for up to 180 days.

Among a subgroup of 266 individuals included in the per-protocol analysis, 98.9% achieved seroprotection following VLA1553 vaccination. The highest geometric mean concentration of neutralizing antibody (nAb) titers was observed at 29 days postvaccination.

Further analysis of immunogenicity among a subset of study participants (n=242) showed nAb titers remained above seroprotective levels in most individuals (96.3%) through 180 days postvaccination.

The VLA1553 vaccine was highly immunogenic among both younger (<65 years) and older adults (≥65 years), with equally high seroprotection rates and nAb titers observed among these 2 groups.

Overall, VLA1553 vaccination was found to be safe and well tolerated.

“If our investigational vaccine is approved, we are confident that it can help address this major, growing and unmet public health threat,” noted Valneva’s chief medical officer, Juan Carlos Jaramillo, MD.²