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Vaccine

Japanese encephalitis vaccine

Brand names: Ixiaro, JEspect

Japanese encephalitis vaccine is an inactivated vaccine used to provide active immunisation against Japanese encephalitis virus for travellers to, and residents of, endemic areas of Asia.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It contains inactivated Japanese encephalitis virus antigen that stimulates production of protective neutralising antibodies.

Prescribing in practice

  • It is contraindicated in those with a previous severe hypersensitivity reaction to the vaccine or its components.
  • A primary course of two doses is given, ideally completed before travel, with a booster for those at continued risk.
  • Risk assessment should weigh the destination, season, duration and nature of travel against the small vaccine risks.

Monitoring

No routine monitoring is required; observe for immediate hypersensitivity following administration.

Counselling the patient

  • Injection-site soreness, headache and muscle aches are common and usually mild.
  • Complete the full course before travelling to be properly protected.
  • Continue mosquito-bite avoidance measures, as no vaccine is fully protective.

Evidence & guidelines

Travel immunisation recommendations follow the Green Book and UKHSA/NaTHNaC guidance based on destination-specific risk.

Reference: UK Green Book; NaTHNaC; Confirm identity and dosing against the manufacturer SPC (eMC) and NICE. Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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