Ixchiq: First FDA-Approved Chikungunya Vaccine

Today, the U.S. Food and Drug Administration approved Ixchiq, the first chikungunya vaccine. Ixchiq is approved for individuals 18 years of age and older who are at increased risk of exposure to chikungunya virus.

The chikungunya virus is primarily transmitted to people through the bite of an infected mosquito. Chikungunya is an emerging global health threat with at least 5 million cases of chikungunya virus infection reported during the past 15 years. The highest risk of infection is in tropical and subtropical regions of Africa, Southeast Asia, and parts of the Americas where chikungunya virus-carrying mosquitos are endemic. However, chikungunya virus has spread to new geographical areas causing a rise in global prevalence of the disease.

The most common symptoms of chikungunya include fever and joint pain. Other symptoms may include a rash, headache, and muscle pain. 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.

“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, M.D., Ph.D., 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.”

Ixchiq is administered as a single dose by injection into the muscle. It contains a live, weakened version of the chikungunya virus and may cause symptoms in the vaccine recipient similar to those experienced by people who have chikungunya disease.

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 most commonly reported side effects by vaccine recipients were headache, fatigue, muscle pain, joint pain, fever, nausea and tenderness at the injection site.

In addition, although not commonly reported, severe chikungunya-like adverse reactions that prevented daily activity and/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. In addition, some recipients had prolonged chikungunya-like adverse reactions that lasted for at least 30 days. The Prescribing Information includes a warning to inform that the vaccine may cause severe or prolonged chikungunya-like adverse reactions.

The FDA is requiring the company to conduct a postmarketing study to assess the serious risk of severe chikungunya-like adverse reactions following administration of Ixchiq.

Transmission of chikungunya virus to newborn babies from pregnant individuals with viremia (virus present in the blood) at delivery has been reported and can cause severe, potentially fatal chikungunya virus disease in newborns. In one study that evaluated whether the vaccine virus was present in the blood after vaccination, most individuals had vaccine virus detected in the blood within the first week following vaccination; the vaccine virus was not detected 14 days after vaccination. The Prescribing Information includes a warning to inform 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. The warning also conveys that when considering administration to pregnant individuals, healthcare providers should take into consideration the individual’s risk of exposure to chikungunya virus, gestational age and risks to the fetus or neonate from disease caused by chikungunya virus in the pregnant individual.

The effectiveness of Ixchiq is based on immune response data from a clinical study conducted in the United States in individuals 18 years of age and older. In this study, the immune response of 266 participants who received the vaccine was compared to the immune response 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.

Ixchiq was approved using the Accelerated Approval pathway. Accelerated approval allows the FDA to approve certain products for serious or life-threatening conditions based on evidence of a product’s effectiveness that is reasonably likely to predict clinical benefit. In the FDA’s evaluation of Ixchiq for accelerated approval, evidence of effectiveness is based on immune response data in clinical trial participants. As a condition for approval for Ixchiq, the FDA is requiring confirmatory clinical studies to be conducted to verify clinical benefit.

Ixchiq was granted Fast Track and Breakthrough Therapy designations and the application was granted Priority Review. In addition, the FDA awarded the manufacturer of Ixchiq a tropical disease priority review voucher, under a provision included in the Food and Drug Administration Amendments Act of 2007. This provision aims to encourage the development of new drugs and biological products for the prevention and treatment of certain tropical diseases.

The FDA granted approval of Ixchiq to Valneva Austria GmbH.