— Agency looks into adverse events, including deaths, in adults 62 years and up
Hold off on inoculating people ages 60 and older against chikungunya infection with the Ixchiq vaccine, the FDA and CDC jointly recommendedopens in a new tab or window amidst an investigation into adverse events.
Two fatalities have been reported among the 17 serious adverse events in vaccinated individuals, mainly neurologic and cardiac events. Six of the reports came from the U.S., while the rest occurred globally among the roughly 80,000 vaccine recipients worldwide.
Because all the events occurred in individuals ages 62 through 89, the FDA and CDC called for a pause in vaccination only in this older age group.
European regulators took similar action last week, calling for a temporary restriction on the use of the live attenuated chikungunya vaccine in those ages 65 and older, “given that studies on Ixchiq mainly involved people below 65 years of age and the vast majority of serious cases concerned people 65 years of age and above.”
One of the fatal cases was an 84-year-old man who developed encephalitis; the other was a 77-year-old man with Parkinson’s disease whose difficulty with swallowing worsened and may have caused aspiration pneumonia.
The FDA granted accelerated approvalopens in a new tab or window to the single-dose Ixchiq vaccine in November 2023 for adults who are at increased risk of exposure to chikungunya virus. The CDC’s Advisory Committee on Immunization Practices (ACIP) has recommendedopens in a new tab or window both Ixchiq and the virus-like particle chikungunya vaccineopens in a new tab or window (Vimkunya), approved in February, for lab workers and U.S. travelers going to a country or territory with a chikungunya outbreak or spending 6 months or more in an area that poses an elevated risk.
However, the six known serious adverse events in the U.S., all in individuals ages 65 and older, were enough for ACIP to revise its recommendationopens in a new tab or window for consideration of use of the live-attenuated vaccine to a “precaution” against use in those 65 and older — particularly those who have underlying medical conditions — when there is elevated risk of exposure without an active outbreak.
In its press releaseopens in a new tab or window, the European Medicines Agency reinforced the product label’sopens in a new tab or window contraindication for Ixchiq in immunocompromised individuals, stating that “persons with a weakened immune system are at greater risk of having complications from vaccines containing live attenuated viruses, regardless of age.”
The chikungunya virus is widespread in tropical and subtropical regions of Africa, Southeast Asia, and parts of the Americas where infected mosquitoes spread the virus to people. The most common symptoms are fever and joint pain, while muscle pain, headaches, rash, or joint swelling can also occur. Most cases aren’t severe, but infants and older adults are at higher risk of serious and fatal infection.
The agencies acknowledged that events reported to its Vaccine Adverse Event Reporting System (VAERS) are not necessarily caused by vaccines, although the live attenuated chikungunya vaccine product label warns that the vaccine may cause severe or prolonged chikungunya-like adverse reactions. Indeed, the FDA safety communication noted, “Some of the postmarketing reports include adverse events that are consistent with severe complications of chikungunya disease, resulting in hospitalization; one person died from encephalitis.”
In the two clinical trials with a total of about 3,500 participants that led to accelerated approval, severe chikungunya-like adverse reactions that prevented daily activity or required medical intervention occurred in 1.6% of Ixchiq recipients (including two hospitalizations) compared with none in the placebo group. Some recipients had prolonged chikungunya-like adverse reactions that lasted for at least 30 days.
FDA said it will conduct an updated benefit-risk assessment for the use of Ixchiq in individuals 60 years of age and older while continuing to watch postmarketing safety reports for the vaccine together with CDC.
