New Japanese Encephalitis Vaccination Guidelines for International Travelers 

Valneva Japanese encephalitis vaccine Ixiaro was approved in the USA during 2009
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Japan (Vax Before Travel)

The Centers for Disease Control and Prevention (CDC) published updated recommendations from its Advisory Committee on Immunization Practices (ACIP) for the Japanese encephalitis (JE) vaccine.

These 3 new CDC recommendations from the Advisory Committee on Immunization Practices (ACIP) committee published on July 19, 2019, clarify the types of international travelers who are at risk for Japanese encephalitis.

This is an important update since Japanese encephalitis (JE) is a vaccine-preventable disease, and about 1 in 4 JE cases is fatal, says the CDC.

1. The new JE recommendation for U.S. travelers are as follows:

  • JE vaccination is recommended for persons moving to a JE-endemic country to take up residence more than 1-month in JE-endemic areas, and frequent travelers to JE-endemic areas.
  • JE vaccine should also be considered for shorter-term travelers with an increased risk of JE based on planned travel duration, season, location, activities, and accommodations.
  • JE vaccine is not recommended for travelers with very low-risk itineraries, such as urban travel only for a short duration, or travel outside of a well-defined JE virus transmission season.

2. Recommendation for an accelerated primary vaccination series for adults between 18-65 years of age:

  • In adults 18‒65 years, the recommended primary vaccination schedule is 2 doses administered intramuscularly on days 0 and 7‒28.
  • Please note that these recommendations differ from the label for IXIARO ®. According to the Prescribing Information for IXIARO in adults 18-65 years, two doses should be administered 7 days apart (accelerated schedule) or 28 days apart (standard schedule), and vaccination should be completed seven days before departure

3, New recommendation for JE booster vaccine dose:

  • For adults and children, a booster dose (3rd dose) is recommended ≥ 1 year after completion of the primary JE vaccination series if ongoing or re-exposure to the JE virus is expected. 

The Japanese encephalitis virus is the leading cause of vaccine-preventable encephalitis in Asia and the western Pacific. This disease is spread through mosquito bites.

Most people infected with JE do not have symptoms or have only mild symptoms. 

However, a small percentage of infected people develop inflammation of the brain, with symptoms including sudden onset of headache, high fever, disorientation, coma, tremors, and convulsions. 

Japanese encephalitis CDC disease insights

  • The JE risk to USA based international travelers is minimal. During 1993–2017, after the first licensure of a JE vaccine in the United States in 1992, a total of 12 cases were reported among U.S. travelers. During this 25-year period, and approximately 4–5 million U.S. citizen trips to Asia annually, the overall incidence of JE among U.S. travelers is estimated to be less than 1 case per million trips to Asia.
  • The proportion of U.S. travelers who receive JE vaccine is unknown and assumed to be very low. A 2007 survey of adult travelers on direct flights from the United States to Asia determined that 415 (25%) of 1,691 participants described itineraries for which JE vaccination should have been considered, including 330 (20%) who planned to spend ≥30 days in a JE-endemic country and another 85 (5%) shorter-term travelers who planned to spend at least 50% of their time in JE-endemic rural areas (181). Of these higher-risk travelers, 47 (11%) reported receiving at least 1 dose of JE vaccine. 
  • Among 164 unvaccinated higher-risk travelers who had visited a healthcare provider to prepare for their trip, 113 (69%) indicated that their healthcare provider had not offered or recommended JE vaccine.
  • The main reasons noted for vaccine non-administration included that JE vaccine was not indicated (55%), the patient declined (23%), or insufficient time to complete the vaccination series (17%) (182).
  • Two studies have investigated the frequency of subclinical JE virus infection. Among 1,000 unvaccinated U.S. infantry soldiers deployed to Korea for at least 330 days during 2008–2011, predeployment and postdeployment serologic testing suggested one possible subclinical infection. 

The CDC says there are 4 types of JE vaccines manufactured and available in different countries, including a live attenuated vaccine, a live recombinant (chimeric) vaccine, inactivated mouse brain-derived vaccines, and inactivated Vero cell culture-derived vaccines. 

Ixiaro is the only JE vaccine licensed and available in the United States. JE-MB, manufactured as JE-VAX, was previously available in the USA, but the production was discontinued and all doses expired in May 2011.

To schedule a pre-trip vaccine and medication counseling session with a local pharmacy, please visit Vax-Before-Travel.

Vaccine financial support programs can be found at Vaccine Discounts.

Japanese Encephalitis news

Any vaccine can cause side effects, which should be reported to a healthcare provider or the CDC.

Published by Vax Before Travel

Article by
Dani Reiter