A single dose of the VLA1553 chikungunya virus vaccine candidate triggered neutralizing antibody production in 98.9% of recipients 28 days later, finds a phase 3 randomized, controlled trial published yesterday in The Lancet.
Chikungunya is a mosquito-borne virus that causes periodic outbreaks of an illness featuring severe joint and muscle pain that can lead to chronic rheumatic (inflammatory) disease.
A team led by vaccine manufacturer Valneva in Vienna evaluated immune responses to VLA1553 in 362 adults (266 vaccine recipients and 96 placebo recipients) at 43 US trial sites from September 17, 2020, to April 10, 2021, and a larger safety cohort.
Safety profile similar to other vaccines
One dose of VLA1553 generated chikungunya virus neutralizing antibodies in 263 (98.9%) of 266 recipients (95% confidence interval [CI], 96.7% to 99.8%) 28 days later, regardless of age.
In the safety analysis involving 3,082 VLA1553 recipients and 1,033 placebo recipients, serious adverse events occurred in 1.5% and 0.8%, respectively, for a similar safety profile to other licensed vaccines. Two serious adverse events were considered related to VLA1553, but both recipients recovered fully.
In a Lancet news release, lead study author Martina Schneider, PhD, of Valneva, said VLA1553 could be the first chikungunya vaccine available for people living in areas where the virus is endemic, travelers to these areas, and regions at risk for an outbreak.
"Our promising results showed good persistence of antibody levels after vaccination, which is important considering that chikungunya outbreaks may recur suddenly," she said. "As age is a risk factor for severity and mortality of chikungunya disease, the strong immune response observed in older participants might be particularly beneficial."
In a related commentary, Kathryn Stephenson, MD, MPH, of Beth Israel Deaconess Medical Center, said that, despite the need for studies on VLA1553 in adolescents and on real-world effectiveness, the vaccine will help chikungunya pandemic preparedness efforts. "Chikungunya virus and other arboviral infections continue to be global threats, spurred on by the expansion of mosquito habitats because of climate change and globalisation of trade and travel," she wrote.
Our promising results showed good persistence of antibody levels after vaccination, which is important considering that chikungunya outbreaks may recur suddenly.