
The U.S. Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) issued an advisory last week for pausing the use of Chikungunya vaccine ‘Ixchiq’ in adults aged 60 years or older. This decision was made after reports of serious neurological and cardiac complications were found in 17 adults worldwide — six of whom were in the US — within one week of vaccine administration.
Status of Chikungunya cases in the U.S.
Chikungunya is a mosquito-borne viral disease transmitted to humans through the bite of infected Aedes mosquitoes. It typically presents with sudden onset of fever and severe joint pain, which can last for months in some cases. Other symptoms may include muscle pain, nausea, headache, rash and fatigue. While serious complications are uncommon, prolonged joint pain and, in some cases, severe illness or death can occur, mostly in children below the age of one or older adults. [1]
In the United States, locally transmitted cases of Chikungunya are rare. Most cases occur in travellers returning from regions with a high risk of Chikungunya, particularly tropical and subtropical areas such as parts of the Caribbean, Central and South America, Africa, Southeast Asia, and the Indian subcontinent. According to multiple news reports, 100 to 200 new cases are reported every year in U.S. travellers.
Ixchiq Vaccine
To address rising cases, the U.S. Food and Drug Administration approved the Ixchiq vaccine in November 2023, developed by the company Valneva for individuals over the age of 18 or more who are at risk of exposure to Chikungunya. Ixchiq was made with the weakened live strain of the virus, administered into muscle as a single dose injection, and may cause symptoms similar to the disease in the recipients.
Ongoing concern
Recent neurological and cardiac complications reported in older adults following vaccination has prompted officials to pause and investigate further. While a direct link to the vaccine is not confirmed, it has been reported that many affected individuals had underlying medical conditions.
What’s next?
The officials are planning to conduct an updated safety risk assessment in individuals above the age of 60 or more before administering the vaccine. Vaccines are put on hold for this age group till further investigations regarding the safety are going on. European officials are also evaluating the issue. In the meantime, Vimkunya by Bavarian Nordic — an alternative to the Ixchiq vaccine has been suggested as a safer option but CDC is yet to follow in practice.
Reference:
“Transmission of Chikungunya Virus.” Centers for Disease Control and Prevention. Accessed May 14, 2025. https://www.cdc.gov/chikungunya/php/transmission/index.html.
(Input from various sources)
(Rehash/Pooja Bansal/MSM)