Japanese Encephalitis

Pregnancy: Limited data — use only if risk is high.

Limited safety data for Ixiaro (inactivated Vero cell vaccine) in pregnancy.

• Administer only if the risk of Japanese encephalitis exposure is judged to be high (prolonged rural travel during transmission season in endemic Asia).

• No teratogenic effects reported in animal studies.

• Live attenuated JE formulations (SA14-14-2, Imojev): contraindicated in pregnancy.

• Defer vaccination until after delivery whenever possible.

Breastfeeding: Limited data — likely safe.

No formal studies of Ixiaro during breastfeeding. As an inactivated vaccine, it is unlikely to pose a risk to the breastfed infant. CDC considers inactivated vaccines generally acceptable during breastfeeding.

Pediatric use:

• Ixiaro: licensed from 2 months of age.

  • 2 months to <3 years: 0.25 mL IM per dose.
  • ≥3 years: 0.5 mL IM per dose.
  • 2 doses on days 0 and 28. Accelerated schedule (days 0 and 7) available for adults ≥18 years only.

• Booster: 1 dose ≥1 year after primary series if ongoing exposure risk.

• Live attenuated SA14-14-2 (in endemic countries): single dose from 8 months of age.

Geriatric use:

• No specific dose adjustment required.

• Immune response may be slightly lower in elderly adults — consider booster if ongoing exposure risk.

• Japanese encephalitis is more severe in older adults (higher case-fatality rate in ≥65 years).

• Standard 2-dose Ixiaro schedule applies.