The Food and Drug Administration has approved the world’s first vaccine to prevent chikungunya, a mosquito-borne illness that can cause debilitating joint pain for months to years.
The vaccine, sold under the brand name Ixchiq, comes at a time when public health experts are increasingly worried about vector-borne illnesses spreading to new regions due to climate change, posing an increased risk to human health.
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“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,” Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, said in a statement.
Chikungunya is a viral disease spread to humans through the bites of infected Aedes mosquitoes, specifically Aedes aegypti and Aedes albopictus. Its symptoms include high fever, severe joint and muscle pain, headaches and rash. Cases of chikungunya have been identified in more than 110 countries in Asia, Africa, Europe and the Americas. There have been more than 2 million cases reported worldwide since 2005, according to the World Health Organization.
Before 2006, the virus was rarely identified in U.S. travelers, according to the Centers for Disease Control and Prevention. But since then, there has been an average of 28 people per year who test positive for the disease. In 2022, the CDC reported 81 travel-related cases.
Public health experts worry that the number of cases will continue to rise because warmer temperatures are optimal for the mosquitoes that carry the virus to multiply and thrive.
“This is very much a vaccine for the future because chikungunya is not here in a big way yet, but it looks like it will be in the coming decades,” said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and co-director of the Texas Children’s Hospital Center for Vaccine Development.
Hotez says climate change and urbanization are the main culprits for the increasing prevalence of vector-borne illnesses such as chikungunya. He added that the approval of Ixchiq lays the groundwork for other vaccines to treat mosquito-related diseases.
The FDA approved Ixchiq, manufactured by biotech company Valneva Austria GmbH, as a single-dose shot for people 18 years and older who are at increased risk of exposure to the disease.
Approval was granted through the FDA’s accelerated approval process, which is designed to expedite “reasonably likely” treatments for serious or life-threatening diseases. Under this process, the FDA evaluated the vaccine’s safety in two clinical studies, and tested its efficacy based on the levels of antibodies present in 266 participants who were given the vaccine. The FDA reported that almost all the participants had the same antibody levels as those shown to be protective in nonhuman primates.
More data on the vaccine is needed to confirm its efficacy and the seriousness of its side effects, which include headaches, muscle pain, fever and tenderness at the injection site. As part of the approval process, the FDA is requiring the manufacturer to conduct additional studies after the shots have been administered.
“As this vaccine is rolling out, it’s going to be important to know that this vaccine prevents disease, and those are the kinds of steps that need to be done to confirm that this is going to be a public health success,” said Albert Ko, an infectious-disease physician and epidemiologist at the Yale School of Public Health.
There are no specific antiviral treatments or other preventive interventions for chikungunya. Most acute symptoms resolve in a few days, but some people can develop long-term arthritic pain. Those most at risk for developing severe disease are newborns who were infected around the time they were born and people older than 65.
