First chikungunya vaccine, Ixchiq, approved by US FDA

Ixchiq, the first chikungunya vaccine, has been approved by the US Food and Drug Administration (FDA) for individuals 18 years of age and older who are at increased risk of exposure to mosquito-borne virus.

Containing a live, weakened version of the chikungunya-causing virus, Ixchiq is administered as a single dose by injection into the muscle and may cause symptoms in the recipient similar to those experienced by people having the viral disease, the FDA said in a statement.

"Infection with chikungunya virus can lead to severe disease and prolonged health problems, particularly for older adults and individuals with underlying medical conditions," said 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," said Marks.

The effectiveness of the vaccine was determined through a clinical study in individuals 18 years of age and older in the US, the agency's statement said.

The level of antibody generated in the 266 vaccinated participants was "based on a level shown to be protective in non-human primates that had received blood from people who had been vaccinated," it said.

The study had compared the immune response of these individuals with that of 96 participants receiving placebo.

The safety of Ixchiq was evaluated in two clinical studies conducted in North America in which about 3,500 participants 18 years of age and older received a dose of the vaccine with one study including about 1,000 participants who received a placebo, the FDA said.

The most commonly reported side effects were headache, fatigue, muscle pain, joint pain, fever, nausea and tenderness at the injection site, the federal agency said.

About 1.6 per cent of the recipients exhibited severe chikungunya-like adverse reactions that prevented daily activity and/or required medical intervention and two were hospitalised. In some, the adverse reactions lasted for at least 30 days, the agency said.

The FDA granted approval of Ixchiq to Valneva Austria GmbH, a biotechnology company in Vienna, Austria, it said.

The agency also said that Ixchiq was approved using the Accelerated Approval pathway, based on evidence of effectiveness obtained through clinical studies.

As a condition for approval for Ixchiq, the FDA requires confirmatory clinical studies to be conducted to verify clinical benefit, the agency said.

The agency also requires the biotechnology company to conduct a postmarketing study to assess the serious risk of severe chikungunya-like adverse reactions following administration of Ixchiq, it said.