Chikungunya Virus VLP Vaccine: Phase 3 Trial in Adolescents and Adults

Chikungunya disease is a growing global public health concern. Chikungunya virus (CHIKV) virus-like particle (VLP) vaccine is a single dose, pre-filled syringe for intramuscular injection.

A pivotal phase 3 randomized, double-blind, placebo-controlled trial was conducted in healthy adolescents and adults 12-64 years of age. Participants received either CHIKV VLP vaccine or placebo on Day 1. Immunogenicity objectives assessed CHIKV serum neutralizing antibody (SNA) titers (NT80) at selected timepoints. Safety was assessed through Day 183 postvaccination.

A total of 2790 participants received CHIKV VLP vaccine and 464 received placebo (n=3454). Coprimary endpoints were met including 1) immunologic superiority to placebo and 2) geometric mean titer at Day 22. Results demonstrated that CHIKV VLP vaccine induced a protective seroresponse (SNA NT80 ≥100; considered the presumptive seroprotective antibody response), in 97% of individuals at Day 15 (2 weeks), in 98% of individuals at Day 22, and in 86% of individuals at Day 183 (6 months). CHIKV VLP vaccine demonstrated a favorable safety profile. The majority of adverse events were self-limited and grade 1 or 2 in severity. The most common adverse events were injection site pain, fatigue, headache, and myalgia.

CHIKV VLP vaccine induces a rapid and robust immune response by Day 15 that lasts through Day 183 postvaccination. These findings support the potential for this vaccine to protect individuals 12-64 years of age from disease caused by CHIKV. (Funded by Emergent BioSolutions Inc. and Bavarian Nordic A/S [as successor in interest to Emergent BioSolutions Inc.]; ClinicalTrials.gov number, NCT05072080). Competing Interest Statement All authors are current or previous employees/contractors of Bavarian Nordic and/or Emergent BioSolutions. Clinical Trial NCT05072080 Clinical Protocols https://clinicaltrials.gov/study/NCT05072080 Funding Statement This study was funded by Emergent BioSolutions Inc. and Bavarian Nordic A/S [as successor in interest to Emergent BioSolutions Inc.] Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: WCG (Western-Copernicus Group) Institutional Review Board gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Footnotes ↵* A complete list of the EBSI-CV-317-004 Study Group is provided in the Supplementary Appendix. Data Availability De-identified data produced in the present study are available upon reasonable request to the authors.