By Zachary Stieber
Contributing Writer
U.S. officials are recommending that adults aged 60 and up not receive the only available chikungunya vaccine after reports that older individuals who received the shot suffered severe symptoms typically associated with the chikungunya virus.
Two of the patients died.
The Food and Drug Administration and the Centers for Disease Control and Prevention said in a Friday alert that they are advising a pause in vaccinating adults aged 60 and up “while the agencies investigate postmarketing reports of serious adverse events, including neurologic and cardiac events, in individuals who have received the vaccine.”
The vaccine, known as Ixchiq and made by Valneva, contains a live, weakened version of the chikungunya virus and can, in some cases, cause symptoms similar to those caused by the virus, according to the FDA’s label for the shot.
After the FDA licensed the vaccine in 2023 and the CDC recommended it in 2024 for adults traveling to certain foreign countries, problems following vaccination began being reported to the health agencies.
As of May 7, those reports include 17 serious adverse events, two of which resulted in death, in people aged 62 and older who received Ixchiq, the agencies said. Six of the serious issues manifested in the United States.
One report detailed how an 86-year-old man who received the vaccine ahead of a trip to South Asia began experiencing problems three days later. He spent 23 days in the hospital, including time in intensive care, before being discharged.
The FDA is going to conduct an updated assessment of the benefits and risks of the vaccine for people aged 60 and older, while the agency and the CDC will keep evaluating reports of problems.
“While the safety of Ixchiq for use in individuals 60 years of age and older is being further assessed, FDA and CDC are recommending a pause in use of the vaccine in this age group. FDA and CDC will update the public when the agencies complete their evaluation of this safety issue,” the agencies said.
“At FDA we take vaccine safety seriously,” Dr. Marty Makary, the FDA’s commissioner, wrote on social media platform X.
Chikungunya virus is transmitted by mosquitoes and primarily present in tropical and subtropical locales. Two hundred and twenty-three Americans reported cases in 2024. Officials estimate some extent of underreporting.
Symptoms include fever and vomiting. The virus, in rare cases, results in death, primarily in the elderly and infants.
The Advisory Committee on Immunization Practices, which advises the CDC on vaccines, recommended in April that the agency update its recommendations to state that, in general, people aged 65 and up should not take Ixchiq. Advisers expressed concerns over the postmarketing reports of problems.
CDC officials said at the time that factors supporting a link between the vaccine and the serious adverse events included all symptoms beginning within five days of vaccination and estimated that every 1,220 doses in elderly individuals would result in a serious adverse event.
In a clinical trial run by Valneva, 11.7% of vaccine recipients experienced issues that are typically caused by the virus, compared to just 0.6% of placebo recipients. In addition, 1.6% of vaccine recipients experienced severe reactions, and 0.5% of the vaccinated suffered from prolonged reactions lasting at least 30 days, versus 0% of participants who received a placebo.
European authorities said on May 7 that they are also reviewing Ixchiq for older individuals. During the review, people aged 65 and older may not take the vaccine, the European Medicines Agency stated.
Valvena said on Monday that it “is committed to upholding the highest safety standards.”
“As highlighted by FDA/CDC, adverse events may not be causally related to vaccination, yet thorough evaluation of these cases is critical to ensure the safe use of Ixchiq, of which over 40,000 doses are estimated to have been utilized to date, worldwide,” the company said.
“Valneva is working with the health authorities and anticipates formal reviews of the post-marketing safety reports in all territories where Ixchiq is approved.”
