Chikungunya disease is a mosquito-borne viral infection that is endemic in parts of Africa, Asia, and the Americas. High fever and intense muscle and joint pain are the main symptoms of chikungunya, which can also be accompanied by fatigue, headache, and nausea. There are no medications capable of preventing chikungunya virus (CHIKV) infection and there is no specific treatment either, so patients are given pain relievers and fever reducers.
The results of a phase 3 clinical trial in which the candidate vaccine against chikungunya VLA1553 developed by the French company Valneva has been tested open a new avenue of hope in the fight to prevent its spread and the risks it implies for the population more vulnerable (newborn babies and the elderly), since they show that it is safe and that it has induced an immune response in 99% (263/266) of those vaccinated, as explained in the article published in The Lancet.
“This could be the first chikungunya vaccine available to people living in endemic regions, as well as travelers to areas that are endemic or at risk of a next outbreak. Our promising results showed good persistence of antibody levels after vaccination, which is important considering that chikungunya outbreaks can suddenly reappear. Given that age is a risk factor for chikungunya disease severity and mortality, the strong immune response seen in older participants could be particularly beneficial,” said Dr. Martina Schneider, Clinical Strategy Manager at Valneva. and lead author of the study.
A single dose of VLA1553 generated antibodies against chikungunya
To carry out the research, 4,115 healthy adults from 43 study areas in the United States were recruited. 3,082 of them received a dose of VLA1553 (by injection in the arm) and 1,033 received a placebo. All participants were included in the safety analysis, but the immune response was only tested in a subgroup of 362 participants, of whom 266 received the vaccine and 96 received the placebo. Immune responses were assessed one week, 28 days, three months and six months after vaccination.
“Climate change is driving the spread of chikungunya-carrying mosquitoes to new areas of the world, so having an effective vaccine is important to deal with future outbreaks”
In addition, these people recorded adverse effects in an electronic diary for 11 days after vaccination. Individuals who experienced adverse events within 21 days of vaccination, such as fever and joint pain, back pain, neurological symptoms, heart problems, rash, or swelling, were closely monitored.
After a single dose, the experimental vaccine induced levels of antibodies considered protective against the disease in 99% (263/266) of the participants, and no differences in immune response were observed based on age. VLA1553 was generally well tolerated in all age groups and most side effects were mild or moderate, the most frequent being: headache (in 32% of vaccinated participants), fatigue (29%), pain muscle (24%), joint pain (18%) and injection site pain (13%).
Six months after vaccination, more adverse events were reported in those who received VLA1553 than in those who received placebo. Overall, 51% (1575/3082) of participants who received VLA1553 and 31% (322/1033) of those who received placebo experienced at least one adverse event judged to be related to vaccination.
Limitations of the trials with the VLA1553 vaccine
The researchers have indicated that their study has some limitations, since it was not carried out in an endemic region, so the pre-existing immunity of the participants to the chikungunya virus is unknown, as well as the safety of the vaccine in this population. Also, the vaccine is made from a weakened version of the live virus, so it may not be suitable for people with weakened immune systems or pregnant women.
They also recognize that for it to be highly effective in the control of endemic diseases, it will be necessary for children to also receive a vaccine against chikungunya, for which reason a study is currently being carried out in adolescents in endemic areas of Brazil to determine the safety and efficacy of the chikungunya vaccine. efficacy of the drug in this age group.
Despite this, as study author Katrin Dubischar, director of the chikungunya vaccine program at Valneva, points out: “Currently, there is no specific treatment or vaccine available against chikungunya, which is a debilitating disease whose symptoms are they can persist in the long term. It is also considered one of the viruses most likely to spread globally, and studies have shown that climate change is driving the spread of mosquitoes that transmit it to new areas of the world. Therefore, having an effective vaccine is important to be prepared for future outbreaks.”
.
