In general, vaccines are regarded safe since such substance is not suspected to give an up-regulation of the heme biosynthesis as a direct effect. However, some vaccines can cause a reaction with high fever persisting over days as a side effect. It is possible that this side effect can trigger an acute porphyric attack in the same way as infections are known to. Vigilance is therefore motivated when administrating a vaccine known to cause reactions with fever.

Fever is reported as a common side effect (very common in children under 18) of the Japanese encephalitis vaccine, and it is possible that this side effect can trigger an acute porphyric attack in the same way as infections are known to. Nausea and vomiting are also reported as common adverse reactions, and may potentially be porphyrinogenic if leading to a decrease in carbohydrate intake.

Based on the pharmacokinetics of the Japanese encephalitis, inactivated, whole virus vaccine there are no conceivable porphyrinogenic effects.

Inactivated Japanese encephalitis virus strain SA14-14-2.

The Japanese encephalitis vaccine is indicated for active immunization against Japanese encephalitis in adults, adolescents, children and infants aged 2 months and older. It is administered as two intramuscular injections, normally given one month apart. Side effects:

The encephalitis vaccine is not metabolized by the Cytochrome P450 system