The U.S. Food and Drug Administration approved Ixchiq, the chikungunya vaccine. Ixchiq is approved for individuals 18 years of age and older who are at increased risk of exposure to chikungunya virus.
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 post marketing study to assess the serious risk of severe chikungunya-like adverse reactions following the 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 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.
