Chikungunya vaccine shows 99% immune response, says study
“The VLA1553 vaccine candidate for chikungunya disease was generally well tolerated and produced an immune response in 99% (263/266) of participants,” said the research paper
In what could be a major breakthrough, a human clinical trial of a vaccine candidate to prevent chikungunya has returned a 99% immune response, according to a research paper published in the Lancet journal on Monday.
“The VLA1553 vaccine candidate for chikungunya disease was generally well tolerated and produced an immune response in 99% (263/266) of participants, according to a phase 3 randomised controlled trial,” said the research paper published in the peer-reviewed medical journal.
Chikungunya is a mosquito-borne viral disease endemic in some regions of Africa, Asia and the Americas. The debilitating disease causes fever in patients four to eight days after they have been bitten, accompanied by headache, fatigue, nausea and severe muscular and joint pain. The joint pain can be prolonged, lasting for weeks, months or even years.
“This could be the first chikungunya vaccine available for people living in endemic regions, as well as for travellers to endemic areas or areas at risk for an upcoming outbreak,” said lead author Dr Martina Schneider, clinical strategy manager at Valneva, a French biotech company.
“Our promising results showed good persistence of antibody levels after vaccination, which is important considering that chikungunya outbreaks may recur suddenly,” Dr Schneider 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.”
There are currently no vaccines for chikungunya, nor is there any effective antiviral treatment for the disease that afflicts millions every year in India and elsewhere in the world.
Researchers, however, said that because the study was not conducted in regions where chikungunya is endemic, they were unable to investigate whether the vaccine protects against subsequent disease. “Instead, the study tested for an immune response at levels that are thought to protect against the disease if infected with the virus,” the paper said.
“At present, there is no dedicated treatment or vaccine available against chikungunya, which is a debilitating disease whose symptoms can persist on a long-term basis,” said co-author Katrin Dubischar, programme director, chikungunya vaccine at Valneva. “Moreover, it is currently regarded as one of the viruses most likely to spread globally, and studies have shown that climate change is driving the spread of the mosquitoes that carry it into new areas of the world. Therefore, having an effective vaccine is important for preparedness for future outbreaks.”
The study enrolled 4,115 healthy adults across 43 sites in the US. Out of these, 3,082 participants were given one dose of VLA1553 via an injection in the arm, and 1,033 were given a placebo. All participants were included in the safety analysis, but the immune response was only tested in a subgroup of 362 participants. Of these 362, 266 given the vaccine and 96 given the placebo.
Participants had their immune responses assessed for one week, 28 days, three months and six months after their vaccination. They also recorded adverse events in an electronic diary for 11 days after vaccination. Those who did experience adverse events within 21 days of vaccination (fever and joint pain, back pain, neurological symptoms, heart problems, rash, or swelling) were monitored more closely.
After a single vaccination, VLA1553 induced antibodies at levels considered to protect against disease was among 99% (263/266) of the participants, the study said. There was no difference in immune response relatd to age.
“VLA1553 was generally well tolerated across all age groups with most adverse events being mild or moderate. In those given the vaccine, the most common adverse events were headaches (experienced in 32% of vaccinated participants), fatigue (29%), muscle pain (24%), joint pain (18%), and pain at the injection site (13%),” the paper said.
After six months, there were more adverse events recorded for those given VLA1553 than those given the placebo. Overall, 51% (1,575/3,082) of participants who were given VLA1553 and 31% (322/1,033) of those who received the placebo experienced at least one adverse event that was considered related to the vaccination. The safety profile in older adults was similar to that of other adults.
Serious adverse events were reported in 2% (46/3,082) of participants exposed to VLA1553 and 1% of participants in the placebo arm (8/1,033). Two of these were classified as related to the vaccine. One was a case of mild muscular pain in a woman with a medical history of fibromyalgia, and the other was a fever, which resulted in hospitalisation. Neither of these cases resulted in death.
“An independent Data Safety Monitoring Board (DSMB) evaluated safety data during the study and did not identify any safety concerns after evaluating all reported adverse events,” said Juan Carlos Jaramillo, chief medical officer at Valneva. “The two related serious adverse events reported during the study both recovered fully and were reviewed by the DSMB who did not raise concerns or consider that there were serious risks caused by the vaccination in general.”
