New VLA1553 vaccine may prevent chikungunya infection: Lancet

43 accredited vaccination trial locations in the United States participated in this double-blind, randomized, multicentre, phase 3 study. Healthy volunteers who were at least 18 years old were eligible. VLA1553 or a placebo was given randomly (3:1) to each participant. The majority of patients having a baseline chikungunya virus antibody level that was seroprotective, as measured by a 50% plaque reduction in a micro plaque reduction neutralization test (μPRNT) with a PRNT50 titre of at least 150, 28 days after vaccination, was the main objective. Each and every person who received immunization was included in the safety analysis. At 12 pre-selected trial sites, immunogenicity studies were performed on a sample of subjects. For these subjects to be included in the per-protocol population for immunogenicity analysis, there may be no significant protocol violations. 

The key findings of this study were:

6100 persons underwent eligibility screening between September 17, 2020, and April 10, 2021. 

1971 individuals were eliminated, and 4093 participants were assigned to receive VLA1553, while 1035 received a placebo. 

Before the trial's conclusion, 358 VLA1553 participants and 133 placebo participants withdrew. 

There were 362 individuals in the per-protocol population for the immunogenicity analysis (266 in the VLA1553 group and 96 in the placebo group). 

Regardless of age, 263 (98%) of 266 individuals in the VLA1553 group developed seroprotective chikungunya virus-neutralizing antibodies 28 days after receiving a single injection of the vaccine. 

VLA1553 was usually well accepted by both younger and older individuals and had an adverse event profile similar to other licenced vaccines.

46 (1%) of the 3082 patients who received VLA1553, as well as eight (0.8%) of the 1033 participants in the placebo group, had serious side events. 

Only two severe adverse events were thought to be connected to the use of VLA1553. Both individuals made a full recovery.

Reference: 

Schneider, M., Narciso-Abraham, M., Hadl, S., McMahon, R., Toepfer, S., Fuchs, U., Hochreiter, R., Bitzer, A., Kosulin, K., Larcher-Senn, J., Mader, R., Dubischar, K., Zoihsl, O., Jaramillo, J.-C., Eder-Lingelbach, S., Buerger, V., & Wressnigg, N. (2023). Safety and immunogenicity of a single-shot live-attenuated chikungunya vaccine: a double-blind, multicentre, randomised, placebo-controlled, phase 3 trial. In The Lancet. Elsevier BV. https://doi.org/10.1016/s0140-6736(23)00641-4