Final analyses from a phase 3 trial evaluating the chikungunya vaccine candidate, VLA1553, showed that the study met all primary and secondary endpoints.

Chikungunya is a mosquito-borne viral disease caused by the chikungunya virus (CHIKV), a Togaviridae virus. While the mortality rate is very low with CHIKV infection, morbidity is high with clinical symptoms that include fever, debilitating joint and muscle pain, joint swelling, headache, nausea, and rash. VLA1553 is a live-attenuated, single dose vaccine candidate designed to delete a part of the chikungunya virus genome. 

The prospective, double-blind, multicenter, randomized phase 3 trial (ClinicalTrials.gov Identifier: NCT04546724) evaluated the safety and immunogenicity of a single shot of VLA1553 in 4115 adults aged 18 years and older. Patients were randomly assigned to receive a single intramuscular vaccination of VLA1553 or placebo. The primary endpoint was the proportion of patients with a seroprotective CHIKV antibody level determined by µPRNT (Micro Plaque Reduction Neutralization Test) at 28 days post-vaccination.  

Findings showed that 98.9% (n=263/266; 95% CI, 96.7-99.8) of participants who received VLA1553 achieved protective levels of CHIKV neutralizing antibodies at 28 days post vaccination. After 6 months post vaccination, 96.3% (n=233/242; 95% CI, 93.1-98.3) of participants maintained the protective CHIKV antibody titers. The vaccine was also found to be equally effective in participants 65 years of age and older. 

The vaccine candidate was generally well tolerated, with the majority of solicited adverse events being mild or moderate in severity. The most common solicited adverse events experienced by approximately 50% of participants were headache, fatigue and myalgia.

“These final pivotal phase 3 results confirm the compelling profile of our single shot vaccine candidate across all age groups,” said Juan Carlos Jaramillo, MD, Chief Medical Officer of Valneva. “Delivering these first ever final phase 3 results for a chikungunya vaccine candidate means that we are a step closer to addressing a major, growing and unmet public health threat.”

The Company expects to begin the presubmission process with the Food and Drug Administration (FDA) in the second quarter of 2022. The FDA previously granted Breakthrough Therapy designation to VLA1553 for this indication.

Reference

Valneva successfully completes pivotal phase 3 trial of single-shot chikungunya vaccine candidate. News release. Valneva SE. Accessed March 8, 2022. https://www.globenewswire.com/news-release/2022/03/08/2398469/0/en/Valneva-Successfully-Completes-Pivotal-Phase-3-Trial-of-Single-Shot-Chikungunya-Vaccine-Candidate.html