A newly developed single-dose vaccine for the chikungunya virus has shown efficacy in a large U.S.-based clinical trial involving over 3,200 adolescents and adults aged 12 to 64 years.
The vaccine, called Vimkunya, is based on a virus-like particle (VLP) platform and was tested in a randomized, double-blind, placebo-controlled phase III study. Among 3,258 participants across 47 sites, 2,790 of them received the vaccine and 464 received placebo.
“At day 22, 2,503 (97.8%) of 2,559 participants in the [vaccine] group had a seroresponse compared with five (1.2%) of 424 participants in the placebo group for the immunogenicity evaluable population,” said lead study author Jason S. Richardson, PhD, of Bavarian Nordic Canada, and his colleagues.
The immune response was rapid. At day 8, 46.6% of the vaccine recipients had already reached the protective threshold. This rose to 96.8% by day 15. Six months postvaccination, 85.5% still had antibody levels above the target threshold.
Age differences were also noted. Adolescents aged 12 to 17 years had a quicker and more durable response, with 70.9% showing protective antibodies by day 8 and 94.8% maintaining them at 6 months. Adults aged 18 to 45 years had an 85.0% 6-month response rate, whereas those 46 to 64 years reached 84.1%.
Researchers also confirmed that the vaccine performed consistently across all three production lots. Antibody levels were similar regardless of the manufacturing batch.
Participants with preexisting immunity to chikungunya virus—those with detectable antibodies prior to vaccination—showed even stronger responses. Their antibody levels were substantially higher following vaccination compared with those who were antibody-negative at baseline.
The vaccine was well tolerated overall. Common side effects included injection-site pain (23.7%), fatigue (19.9%), headache (18.0%), and muscle pain (17.6%). These were mostly mild or moderate, resolving in about 2 days. Serious adverse events were rare (0.8%) and none were linked to the vaccine.
One pregnancy during the trial resulted in a birth defect, but the researchers determined it was unrelated to the vaccine as a result of preexisting maternal conditions. No other safety concerns were identified.
The novel vaccine doesn't contain live virus and cannot replicate in the body, making it a potential option among patients with weaker immune systems. It is administered as a single, pre-filled syringe for easier use and faster preparation.
The findings supported the use of the novel vaccine to protect individuals aged 12 years and older against chikungunya virus. The researchers plan to evaluate its real-world effectiveness in regions where chikungunya is endemic.
Full author disclosures are provided in the original study.
Source: The Lancet
