CHIKUNGUNYA VACCINE

KEY POINTS

1.       Chikungunya (CHK) is a viral illness transmitted by mosquito bite.

2.       Geography: Many Asian, European countries, West Africa, the Americas, and Australia.

Outbreaks regularly occur, and so travelers should check cdc.gov to get current disease activity information.

Recent outbreaks (2025),

China

India

Thailand

Indonesia

Singapore

Italy

West Africa

Brazil

Paraguay

Argentina

Boliva

Caribbean

Puerto Rico

3.       Disease: CHK viremia (virus in the bloodstream) develops within a 3-7 days of a mosquito bite. The virus directly infects joints, joint linings, and muscle, invoking an inflammatory response there which may sustain for some days to several weeks of infection. However, CHK RNA genetic material may persist in tissues for weeks to months, leading to chronic arthritis or joint pains, up to 3 months, in 70% of people, with a clinical picture resembling symmetrical rheumatoid arthritis.

                The acute illness is a non-specific viral syndrome: fever, headache, joint pains, malaise, muscle aches, and diffuse rash (starting on limbs 3 days or so after illness onset and lasting 3-7 days) in 40-75%. The rash is similar to dengue virus infection.

                Uncommonly/rarely severe complications occur, even causing death, most often in those over 65 yrs with diabetes mellitus and/or cardiovascular disease.  Such complications include respiratory failure, cardiovascular collapse, and neurological disorders.

                25-75% of patients develop chronic or relapsing, sometimes incapacitating, musculoskeletal disease and symptoms, most often joint pain and/or or stiffness. Duration is highly variable from many studies, from 20 months to 13 years, or more.

Prevalence: See above, “Geography”.

Transmission: Aedes aegypti or Aedes albopictus mosquito species carry the virus (as well as dengue and Zika virus which produce acute illness very similar to CHK). These mosquitoes feed mostly during daytime, but can at night. They are rural and urban. They are at highest levels during rainy, warm seasons, and wherever there is substantial standing water. So, they are most present in tropical/ subtropical aeras, but have expanded northward with climate change.  Current U.S. maps show A. aegypti as far north as Oregon, Michigan, and New York; A. albopictus up to Washington state, Michigan, and Vermont. They can be brought home with travelers.

 

4.       Treatment:

a.       There is no anti-viral medicine for CHK.

b.       Treatment is supportive with fluids, anti-inflammatory medications, pain control, and management of complications.

5.       Prevention

a.       Mosquito Barrier Methods,

1)       Clothing covering as much exposed skin as possible

2)       Mosquito nets (sleeping)

3)       DEET (30% or more) repellents on exposed skin

4)       Permethrin treatment of clothing

b.       Vaccines

1)       IXCHIQ: a LIVE vaccine; for those 18 yrs-old and older

a)       Contraindicated,

(1)     Pregnant or possibly pregnant

(2)     Immune-compromised by disease or medical treatments

b)       Given at least 2 weeks prior to exposure

c)       Single intramuscular injection

d)       Possibly lifelong

e)       Relatively contraindicated in those 60 yrs-old and older, especially with significant pre-existing medical problems such as diabetes mellitus and/or active or historical cardiovascular disorders.

Note: Those ≥60yrs-old must consider the risk-benefit of the vaccine vs. CHK disease.

f)        IXCHIQ can cause vaccine-related chikungunya-like disease, sometimes severe in anyone, but especially the elderly.

2)       KIMGUNYA: a killed vaccine; for those 12 yrs-old and older

All the above information on IXCHIQ is relevant to this vaccine, except,

a)       Not contraindicated in the immune-compromised

b)       Not absolutely contraindicated in pregnant or possibly pregnant individuals, though all vaccines are best avoided in pregnancy, especially during the first trimester or within 2 weeks of delivery. Any vaccination during pregnancy should be discussed with your personal physician and OB-GYN physician prior to receiving it.

c)       This vaccine may cause CHK-like illness, but not likely the severe form that can occur with IXCHIQ, though that has not yet been proven.

3)       It is clear that both IXCHIQ and KIMGUNYA produce neutralizing (protective?) antibody against CHK, but efficacy in preventing infection or decreasing disease severity or complications is still not established. It would seem likely that the antibody produced would provide benefit in these matters, but other immune system defenses may also be at work in prevention and moderation of the disease.

This will need to be followed over time by checking the vaccines manufacturers’ website for latest data on efficacy.

                It does appear the vaccines are about equal in producing CHK virus neutralizing antibody.

4)       NOTE: Currently, CDC suggests routine (brief-stay) tourist travel does not justify these vaccines, though the specific travel and medical facts of each individual must be considered in requesting or declining CHK vaccination.

 

Edward R. Rensimer, MD