FDA approves first vaccine against chikungunya virus for people over 18

The U.S. Food and Drug Administration on Thursday approved the first vaccine against chikungunya virus, a disease that is primarily transmitted to people through infected mosquito bites. 

The vaccine, Ixchiq, was approved for people 18 years and older who are at an increased risk of exposure to the virus, in what officials said is an emerging global health threat, with at least 5 million cases reported during the past 15 years. 

Experts said the highest risk of infection is in the tropical and subtropical regions of Africa, Southeast Asia, and parts of the Americas, where the virus-carrying mosquitoes are endemic. But chikungunya virus has spread elsewhere, causing more cases of the disease globally, officials said in a release.  

"Infection with chikungunya virus can lead to severe disease and prolonged health problems, particularly for older adults and individuals with underlying medical conditions," said Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research. "Today's approval addresses an unmet medical need and is an important advancement in the prevention of a potentially debilitating disease with limited treatment options."

Officials said Valneva, a French bio-tech company, was given "accelerated approval" by the FDA to create the Ixchiq vaccine due to the seriousness and life-threatening conditions caused by the disease. 

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Chikungunya symptoms

The most common symptoms of chikungunya are fever and debilitating joint pain, which may persist for months or years, according to the FDA. Other symptoms include rash, headache, and muscle pain.

The FDA also said that chikungunya virus is also severe and potentially fatal to newborn babies from pregnant individuals at delivery. Doctors recommend those infected to rest, drink fluids, and take over-the-counter medicine to treat pain and fever.

Today, people infected with chikungunya can receive a single-dose injection into the muscle to treat the sickness. The vaccine contains a live and weakened version of the virus that may cause people to experience symptoms similar to the disease, officials said. 

The FDA said the Ixchiq vaccine was evaluated in two clinical studies in North America with about 3,500 people 18 years or older, receiving a dose of the medicine and about 1,000 participants who received a placebo.

Officials said the most commonly reported side effects of the vaccine were headache, fatigue, muscle pain, joint pain, fever, nausea, and tenderness at the injection site. Experts said severe chikungunya-like reactions that prevent daily activity are uncommon, with only 1.6% of vaccine recipients and none of the placebo recipients requiring medical intervention. 

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Two vaccine recipients with severe adverse reactions were hospitalized, officials said. Some patients reported reactions that lasted for at least 30 days. In one study, most individuals were found to have the virus in their bloodstream one week after vaccination; the vaccine virus was undetected two weeks following inoculation, according to the FDA.

The vaccine includes caution labels about possible severe reactions, including a warning that says experts are unsure if the virus can be transmitted from pregnant people to newborns.

The FDA is requiring researchers to conduct a postmarket study of the medicine to assess potential risks.