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  • A first of its kind vaccine has been approved by the FDA to prevent infections with the chikungunya virus.
  • The virus is most prevalent in semi-tropical and tropical areas, such as Central and South America, Southeast Asia, and Africa.
  • Tropical diseases could spread more widely in the U.S. as the climate changes.

This month the U.S. Food and Drug Administration (FDA) announced the approval the first vaccine to treat Chikungunya, a tropical disease.

The drug, named Ixchiq and produced by Austrian firm Valneva, is to be used to prevent infections with Chikungunya virus, which predominantly occur in semi-tropical and tropical areas like South and Central America, Africa, and Southeast Asia.

Chikungunya virus is carried by mosquitoes and was first identified in the 1950’s, according to the World Health Organization (WHO). It’s characterized by symptoms that are similar to other mosquito-borne viruses like Zika and dengue.

Those symptoms include muscle soreness, fever, fatigue, and joint pain.

Ixchiq was approved after being put on the fast track by the FDA. It was also given priority review.

According to the European Centre for Disease Prevention and Control, the countries currently experiencing the highest cases include Brazil, Paraguay, Argentina, and Bolivia.

Brian Labus (MPH, PhD), assistant professor at the UNLV School of Public Health and an infectious disease epidemiologist, says that in the US the primary focus is to protect travelers and those who work in laboratories that handle the virus.

“This is not a vaccine for the average person, this is not something we’re going to recommend that the general public goes out and gets anytime soon,” Labus said. “This vaccine will be specifically used for people who are traveling to countries where they’re seeing outbreaks of this disease. So it’s a protective step if you’re heading into a high risk area.”

The WHO notes that chikungunya virus rarely leads to death. According to the European Centre for Disease Prevention and Control, the countries currently experiencing the highest cases include Brazil, Paraguay, Argentina, and Bolivia.

The last time any cases were reported to be transmitted locally in the U.S. was in 2014 and 2015. From 2015 to 2022, the US reported 1,757 travel-associated cases in total, according to the CDC.

Dr. William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center, says that developing this vaccine may also help protect people in the U.S. as the climate changes.

The primary concern is that, as the planet warms, the mosquitos that carry viruses like chikungunya could move north into the U.S.

“Should there be spread of Chikungunya virus in areas of the United States, for example, Puerto Rico, or South Florida or someplace like that, where it begins to get a hold, then we have the vaccine readily available,” Schaffner said. “It would be licensed and we could start using it more widely, if needed. So, this is an important vaccine to have on the shelf ready to go.”

Ixchiq is a live-attenuated vaccine. These types of vaccines are modified so that the virus is weakened and unlikely to cause a full infection.

Antigens in the vaccine, in this case the weakened virus, help prompt an immune response in the body where antibodies and white blood cells are created to fight the perceived infection. Once this occurs, the immune system has the ability to quickly create these antibodies when exposed to the virus in the future.

Since chikungunya is not predictable in terms of when outbreaks occur, in this case immune responses and lab tests allowed the FDA to be confident that the vaccine is safe and effective.

Schaffner says that we can look at other rare conditions, like adolescent meningococcal disease (which leads to bacterial meningitis), as an example of how scientists can create a vaccine without needing widespread studies. Part of that process is by immunizing a thousand people or more and testing the immune response.

“If you didn’t have that sort of flexibility, a vaccine against a rare disease could never be licensed.”

Labus points to conditions like MERS and SARS as examples where a similar approach had to be taken.

“You can’t plan your clinical trial on the hope that there’s an outbreak in the specific area you’re working in. So it’s just very difficult because you’re really chasing the virus rather than looking at diseases like influenza that we know we have a flu season. We know we’re going to have a lot of cases every year.”

Labus says that while many countries have faced outbreaks of the virus in the past, the key is to find out if the location that you are going to is currently facing an influx of cases. He recommends looking at the CDC’s travelers’ health site to identify the preventive steps you need to take rather than relying on a simple list of case numbers.

“So, even though you can list the countries that have had it in the past, where there’s some potential for risk, it’s still not recommended just traveling to those countries to get the vaccine. It’s traveling to countries that are seeing current outbreaks.”

Traveling to an area where chikungunya is a concern could also cause a hit to your wallet. Schaffner says that the newer a vaccine is, the more costly it is likely to be. He puts the cost of Ixchiq at approximately $350.

“Because these travelers’ vaccines are not usually paid for by your routine medical insurance… it will not be inexpensive but all these new vaccines that are now being developed tend to be a bit pricey.”