Vaccine Info

Ixiaro Japanese Encephalitis Vaccine


Ixiaro is an inactivated, adsorbed Vero cell culture-derived vaccine. It is prepared by propagating JEV strain SA14-14-2 in Vero cells.

Multiple viral harvests are pooled, clarified and concentrated. The virus suspension is treated with protamine sulfate to remove contaminating DNA and proteins.

The resulting partially purified virus is processed through a sucrose density gradient centrifugation step and fractionated. Each fraction is analyzed for the presence of virus, and fractions with the highest virus activity are pooled to give a purified virus suspension.

The purified virus is then inactivated by treatment with formaldehyde. The preparation is adjusted to a specified protein concentration and formulated by addition of aluminum hydroxide.


Ixiaro is indicated for active immunization for the prevention of disease caused by Japanese encephalitis virus (JEV) and is approved for use in individuals 2 months of age and older.


Ixiaro is administered as an intramuscular injection.

  • Primary Series:
    • Children 2 months to <3 years of age: Primary immunization with IXIARO consists of two (2) 0.25 mL doses, administered 28 days apart.
    • Individuals 3 years of age and older: Primary immunization with IXIARO consists of two (2) 0.5 mL doses, administered 28 days apart.
    • Complete the primary immunization series at least 1 week prior to potential exposure to JEV.
  • Booster Dose:
    • Individuals 17 years of age and older: If the primary series of two doses was completed more than 1 year previously, a booster dose may be given if ongoing exposure or re-exposure to JEV is expected.
    • Infants, children and adolescents 2 months to <17 years of age: The safety and immunogenicity of a booster dose has not been evaluated.

Ixiaro was approved in the US on March 30, 2009, which is also its international birthdate.

Currently, Ixiaro is licensed in Australia, New Zealand, Europe, Canada, Switzerland, Hong Kong, Singapore, and Israel.

Japanese encephalitis (JE) virus is the leading cause of vaccine-preventable encephalitis in Asia and the western Pacific.

For most travelers to Asia, the risk for JE is very low but varies based on the destination, length of travel, season, and activities.


November 29, 2019: The European Medicines Agency (EMA) has approved the extension of the shelf life the Japanese encephalitis vaccine IXIARO from 24 months to 36 months.

Clinical Trials

Clinical Trial NCT00604708: Immunogenicity Study of the Japanese Encephalitis Vaccine IC51

  • The objective of this Phase 3 study is to demonstrate the non-inferiority of the Japanese Encephalitis vaccine IC51 compared to JE-VAX in healthy subjects aged > or = 18 years


November 29th, 2019