ACIP: Chikungunya Vaccine Recommended for Some Travelers, Lab Workers

Adults should get the chikungunya vaccine (Ixchiq) if they are traveling to a country or territory where there is an outbreak of the mosquito-borne viral illness, according to a unanimous vote by the CDC’s Advisory Committee on Immunization Practices (ACIP).

The committee also recommended that the chikungunya vaccine may be considered when traveling to a country or territory without an outbreak but with evidence of chikungunya viral transmission within the last 5 years for the following groups:

• People over the age of 65, particularly those with underlying medical conditions like diabetes or heart disease, who are likely to have at least moderate (2 weeks or more) exposure to mosquitoes in indoor and outdoor settings
• People staying in such an area for 6 months or more

In a separate unanimous vote, the committee recommended chikungunya vaccination for selected laboratory workers who might be exposed to live chikungunya virus. Such individuals include those undertaking research or very specific diagnostic work using the live virus, such as plaque reduction neutralization tests, the committee indicated. The vaccine was not deemed necessary for workers handling routine clinical samples.

The chikungunya virus is an alphavirus transmitted by mosquitoes that is widespread in tropical and subtropical regions. There have been at least 5 million cases of chikungunya virus infection reported during the past 15 years globally, Susan Hills, MBBS, of CDC’s Arboviral Diseases Branch Division of Vector-Borne Diseases in Fort Collins, Colorado, told the committee during the second day of the two-day ACIP meeting.

The CDC posts information about outbreaks on its Traveler’s Health website. For chikungunya, it currently lists only a Level 2 warning for enhanced precautions in Timor-Leste.

Since 2019, there have been outbreaks in Djibouti, Myanmar, and Congo in addition to ongoing incidence in Mexico and most countries in Central and South Americas that would put higher-risk travelers in line for the vaccine. These areas with recent viral transmission include a scattering of countries along the equator in Africa, across India and adjacent countries, and through the island nations around Indonesia, Malaysia, and the Philippines.

Approximately 100 to 200 cases of chikungunya are reported among U.S. travelers every year, and infection is most commonly acquired in Asia and the Americas.

Chikungunya disease typically causes a self-limiting febrile illness with severe, often debilitating arthralgia, Hills explained, but ongoing arthralgia remains in up to half of patients at 3 months and up to 30% at 12 months. Serious complications can occur and include myocarditis, hepatitis, acute renal disease, and neurologic illness. Deaths are rare and occur mostly in older adults, particularly those with comorbidities.

In November 2023, the FDA granted accelerated approval of the first vaccine for chikungunya virus for adults. According to recent data, the single-dose, live-attenuated vaccine is highly effective in the short-term and at least 12 months after protection, Hills said.

However, about 12% of recipients have chikungunya-like reactions to the vaccine, 1.6% of recipients have severe reactions, and about 0.5% have prolonged reactions of 30 days or longer. The vaccine is contraindicated for use in immunocompromised people and anyone with a history of a severe allergic reaction to any component of the vaccine.

Recommendations from ACIP are not considered final until they are published in the Morbidity and Mortality Weekly Report.

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