The first vaccine for chikungunya, an emerging mosquito-borne global health threat marked by fever and joint pain, has been granted accelerated approval by the US Food and Drug Administration (FDA).
The vaccine, called Ixchiq, was granted fast-track and breakthrough-therapy designations in June, and the application has now received a priority review designation.
The risk for chikungunya infection is highest in the tropical and subtropical regions of Africa, Southeast Asia, and parts of the Americas, where chikungunya virus-carrying mosquitos are endemic, according to the FDA. However, the chikungunya virus has been spreading geographically, increasing its global prevalence.
At least 5 million cases have been reported globally in the past 15 years, the agency reported yesterday.
The new vaccine is approved for adults 18 years or older who are at increased risk for exposure to the virus.
“Infection with chikungunya virus can lead to severe disease and prolonged health problems, particularly for older adults and individuals with underlying medical conditions,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said in a statement. The “approval addresses an unmet medical need and is an important advancement in the prevention of a potentially debilitating disease with limited treatment options.”
In addition to fever and joint pain, common symptoms include rash, headache, and muscle pain. It can be fatal for newborns.
“Some individuals may experience debilitating joint pain that persists for months or even years. Treatment includes rest, fluids, and over-the-counter medications for pain and fever,” the FDA states.
The virus name chikungunya comes from the Kimakonde language, which is spoken in southeast Tanzania and northern Mozambique, and means “to become contorted,” according to the World Health Organization.
Warnings About Side Effects
The new vaccine is administered as a single-dose injection into the muscle. Because it contains a live, weakened version of the chikungunya virus, it can cause chikungunya-like symptoms, the FDA notes. The prescribing information includes a warning to that effect.
The safety of the vaccine was assessed in two clinical trials conducted in North America. About 3500 adults received a dose of the vaccine and, in one study, about 1000 participants received placebo.
The most reported side effects of the vaccine were headache, fever, fatigue, muscle and joint pain, nausea, and injection-site tenderness.
“Although not commonly reported, severe chikungunya-like adverse reactions that prevented daily activity or required medical intervention occurred in 1.6% of Ixchiq recipients and none of the placebo recipients. Two recipients with severe chikungunya-like adverse reactions were hospitalized,” the FDA states.
Some vaccine recipients had chikungunya-like reactions that lasted at least 30 days, the FDA adds. Considering the potential for adverse effects, the agency is requiring the manufacturer, Valneva Austria GmbH, to conduct a postmarketing study.
Disease Can Be Fatal in Newborns
When the virus is present in the blood of a pregnant person during delivery, chikungunya can be transmitted to the baby, as reported, and can cause severe, potentially fatal chikungunya in newborns.
Although the prescribing information warns that, “it is not known if the vaccine virus can be transmitted from pregnant individuals to newborns, nor is it known if the vaccine virus can cause any adverse effects in the newborn,” healthcare providers considering offering the vaccine to pregnant people should weigh that individual’s risk for exposure to chikungunya, gestational age, and potential risks to the fetus or neonate from disease caused by the virus.
The effectiveness of the vaccine is based on the immune response seen in a clinical study conducted in US adults. In that study, the immune response of 266 participants who received the vaccine was compared with that of 96 participants who received placebo.
“The level of antibody evaluated in study participants was based on a level shown to be protective in non-human primates that had received blood from people who had been vaccinated. Almost all vaccine study participants achieved this antibody level,” the FDA states.
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