(CTN News) – A phase 3 randomized controlled study published in The Lancet has shown that a single dose chikungunya vaccine developed by French biotech company Valneva is safe and produces an immune response.
VLA1553 induced antibody levels at a level that is considered protective against disease in 99 percent of participants (263/266) following a single vaccination. According to age, there was no difference in immune response.
In spite of the fact that antibody levels declined 28 days after vaccination, seroprotection persisted in more than 96% of participants (233/242) six months after vaccination.
As the lead author, Martina Schneider, Clinical Strategy Manager at Valneva, said, “This may be the first chikungunya vaccine available to people living in endemic regions, as well as travelers to endemic regions or areas at risk for future outbreaks.”
We found good persistence of antibodies after vaccination, which is important since chikungunya outbreaks may recur suddenly. Because age is a risk factor for severity and mortality of Chikungunya disease, the strong immune response observed in older participants might be particularly beneficial,” Schneider concluded.
VLA1553-301, however, was not tested in regions where Chikungunya is endemic, but in the United States. Thus, researchers were unable to test whether the vaccine protects against subsequent diseases.
Instead, the study examined immune responses at levels that are thought to protect against infection with the virus.
In some parts of Africa, Asia, and the Americas, chikungunya is an endemic mosquito-borne disease caused by the chikungunya virus (CHIKV).
Infected mosquito bites cause a fever in patients roughly four to eight days after they have been bitten. The most common symptoms include headaches, fatigue, nausea, and severe pain in the muscles and joints.
The disease caused by CHIKV infection is not currently prevented by vaccines, nor is it effectively treated with antiviral medications.
There were 4,115 healthy adults enrolled in the study throughout the United States. There were 3,082 participants who received one dose of VLA1553 (via an injection in the arm) and 1,033 who received a placebo.
In general, VLA1553 was well tolerated across all age groups, with the majority of adverse events being mild or moderate.
The most common adverse events experienced by those who received the vaccine were headaches (32 percent), fatigue (29 percent), muscle pain (24 percent), joint pain (18 percent), and injection site pain (13 percent).
There was at least one adverse event related to the vaccination experienced by 51 percent of participants who received VLA1553 and 31 percent of those who received a placebo after six months.
Observed miscarriages in the population receiving VLA1553 were slightly higher than expected in the general population (23 percent versus 11-16 percent). However, this could be the result of natural variation in the small sample size, according to the researchers.
Some limitations have been acknowledged by the researchers, such as the fact that the vaccine is made from a weakened version of the live virus, so it is likely not to be suitable for pregnant women and those with weakened immune systems.