FDA Approves First Chikungunya Vaccine, Ixchiq, for Adults

The US Food and Drug Administration (FDA) has approved the first-ever vaccine for chikungunya, a mosquito-borne virus known for causing fever and debilitating joint pain. Announced on November 09, 2023, it will offer a new shield against a disease that has increasingly threatened global health.

Named Ixchiq, the vaccine has been fast-tracked through the FDA’s approval process — receiving both fast-track and breakthrough-therapy designations earlier in June, followed by a priority review. 

The FDA’s approval of Ixchiq is specifically for adults aged 18 and older who are at increased risk of exposure to the virus. Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, highlighted the vaccine’s importance, stating that it addresses an unmet medical need and offers a significant advancement in preventing a disease that has limited treatment options.

Chikungunya, characterized by fever and severe joint pain, has been a persistent threat in tropical and subtropical regions, particularly in parts of Africa, Southeast Asia, and the Americas. The virus, carried by mosquitoes, has seen a worrying spread in geographical reach, heightening the urgency for an effective preventive measure. Over the past 15 years, the global case count has soared to at least 5 million, underscoring the critical need for this vaccine.

Chikungunya’s symptoms extend beyond fever and joint pain, often including rash, headache, and muscle pain. In severe cases, especially in newborns, it can be fatal.

The vaccine, administered as a single-dose injection, contains a live, weakened version of the virus. This composition, while effective, means it can induce mild chikungunya-like symptoms. The FDA’s approval comes with a cautionary note about these potential side effects, which were observed in clinical trials involving approximately 3,500 adults in North America. The most common side effects reported were headache, fever, fatigue, muscle and joint pain, nausea, and injection-site tenderness. Notably, severe chikungunya-like adverse reactions occurred in 1.6% of Ixchiq recipients, with two cases leading to hospitalization.

Given the potential for side effects, the FDA has required Valneva Austria GmbH, the vaccine’s manufacturer, to conduct a postmarketing study. This study will further evaluate the vaccine’s safety and efficacy.

The vaccine’s effectiveness was determined based on immune responses observed in a U.S. clinical study. This study compared the immune response of 266 vaccinated participants against 96 who received a placebo. The level of antibody response was benchmarked against a level shown to be protective in non-human primates.

This FDA approval of Ixchiq marks a critical step in the global fight against chikungunya, offering hope and protection to millions at risk of this virus.