Chikungunya Vaccine Shows Promise in Adults

TOPLINE:

The chikungunya virus virus-like particle (CHIKV VLP) vaccine achieved 100% seroconversion in adults who had previously received alphavirus vaccines and alphavirus vaccine–naive control individuals, with the previous recipients showing a faster immune response. Moreover, both groups had similar safety profiles.

METHODOLOGY:

• Researchers conducted an open-label, phase 2, randomized controlled trial at two clinical sites in the United States to assess the immunogenicity and safety of CHIKV VLP among previous recipients of alphavirus vaccines and alphavirus vaccine–naive control individuals.
• They enrolled 60 participants (median age, 47 years; 33% women), of whom 30 were previous recipients of alphavirus vaccines and 30 were age- and sex-matched alphavirus vaccine–naive control individuals.
• The study included a 60-day screening period followed by 29-day treatment and observation period, wherein the participants received a single 40-μg intramuscular dose of CHIKV VLP vaccine and aluminum hydroxide adjuvant on day 1. Follow-up continued until day 182.
• The primary endpoint measured was the anti-CHIKV seroconversion rate at day 22 in both the groups; seroconversion was defined as a fourfold or higher increase in anti-CHIKV neutralizing antibody concentration from the baseline.
• Secondary endpoints included anti-CHIKV neutralizing antibody seroconversion rates on days 8, 29, 57, and 182 and geometric mean titers.

TAKEAWAY:

• Seroconversion was achieved by 100% (95% CI, 88.6-100) of participants by day 22.
• A higher proportion of previous recipients of alphavirus vaccines seroconverted at the earliest time point of 8 days postvaccination compared with alphavirus vaccine-naive control individuals (93.3% vs 66.7%; P =.021).
• Anti-CHIKV total immunoglobulin G antibody seroconversion occurred in all participants in each group and persisted up to day 182 in 93.3% of previous recipients of alphavirus vaccines and 96.7% of control individuals.
• No significant differences were noted in solicited adverse events between the groups, and no serious or potentially life-threatening adverse events related to vaccine were reported.

IN PRACTICE:

“The findings suggest an enhanced anti-CHIKV immune response in previous alphavirus vaccine recipients, given the more rapid development of neutralising and binding antibodies. CHIKV VLP vaccine appears to be well tolerated and immunogenic in previous recipients of heterologous alphavirus vaccines,” the authors wrote.

SOURCE:

This study was led by Melinda J. Hamer, MD, Walter Reed Army Institute of Research in Silver Spring, Maryland, and James M. McCarty, MD, Stanford University School of Medicine in Stanford, California. It was published online on February 12, 2025 in The Lancet Microbe.

LIMITATIONS:

This study was limited by its small size, open-label nature, missed visits due to COVID-19 restrictions, and racial imbalance between groups. The duration between alphavirus and CHIKV VLP vaccinations was not standardized, thus preventing the assessment of the impact of timing on immunogenicity.

DISCLOSURES:

This study received funding from the Defense Health Program, Emergent Travel Health, and Bavarian Nordic A/S. Two authors reported being employees of Bavarian Nordic A/S. One author reported receiving consulting fees from Emergent Travel Health Inc. and Bavarian Nordic A/S and receiving payment or honoraria for presentations, speakers’ bureaus, manuscript writing, or educational events. Some other authors reported having stocks and stock options in Emergent BioSolutions.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.