1. A novel vaccine based on virus-like particles (VLPs) was immunogenic and well-tolerated against chikungunya virus.
Evidence Rating Level: 2 (Good)
Study Rundown: Chikungunya virus is a mosquito-borne virus endemic to the tropical and subtropical regions of Africa and south and Southeast Asia. Although rarely lethal, infection with chikungunya virus is associated with significant long-term morbidities in a large number of patients, such as chronic arthritis. At this time, there are no drugs or vaccines for treatment or prevention. Results of a phase-1 open-label trial published in Lancet today showed that a novel virus-like particle (VLP) vaccine was immunogenic in a small trial involving 25 participants. The vaccine was well tolerated with no serious adverse events reported. If subsequent trials are successful, the vaccine may be of value in endemic areas of the world. No definitive safety and efficacy conclusions can be drawn due to the small sample size (n=25) of this phase 1 trial.
The study was funded by the Intramural Research Program of the Vaccine Research Center, National Institute of Allergy and Infectious Diseases, and National Institutes of Health.
In-Depth [phase 1 open-label trial]: This is a phase 1 open-label trial that assessed the safety and immunogenicity of a novel VLP vaccine against chikungunya virus. The vaccine consisted of chikungunya VLPs composed of the E1, E2 and capsid proteins from the chikungunya virus strain 37997. The vaccine was administered intramuscularly at weeks 0, 4, and 20 at the following doses: 10 ug (n=5), 20 ug (n=10) and 40 ug (n=10). Immunogenicity was measured by ELISA and by neutralization antibody assays.
Antibodies were detected by ELISA in most participants after the first vaccination (100% in the 10 ug and 40 ug groups, and 80% in the 20 ug group). Antibodies were boosted to peak titers at 4 weeks after the 3rd vaccination. The geometric mean titers were not significantly 4 weeks after the 2nd vaccination compared with 4 weeks after the 3rd vaccination (p≥0.10). Neutralizing antibodies against an outbreak strain, OPY1, were detected in all participants 4 weeks after the 2nd vaccination.
There were no serious adverse events. 10 (40%) participants reported mild systemic reactogenicity. There were 7 mild-to-moderate adverse events within 2-4 weeks after vaccination: 4 mild transient alanine aminotransferase increases, 2 mild and 1 moderate transient neutropenia. The mild-to-moderate adverse events all resolved without clinical sequelae.
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