Japanese encephalitis vaccine: study note

Vaccine

Inactivated vaccine (IXIARO®), NO live virus.
Adjuvant: Aluminium hydroxide (improves immunogenicity).
Storage: +2°C to +8°C and protected from light.

Administration

• 0.5ml suspension in a pre-filled syringe.
  IM injection (deep subcutaneous injection can be given to individuals with bleeding disorders).
• Children 2 months – 36 months: dose 0.25 ml
• Children 3 years and over and adults: dose 0.5 ml

Primary immunisation

Primary immunisation should ideally be completed at least one week before potential exposure to the Japanese encephalitis virus. Full immunity takes up to one week to develop after the second dose.

Standard schedule	Rapid schedule
1st dose at day 0 2nd dose at day 28	1st dose at day 0 2nd dose at day 7
	1st dose at day 0 2nd dose on day 28

Booster dose

Age group	First booster	Second booster
2 months – 18 years	A booster dose at 12 months should be considered for those at continued / further risk.	No long-term seroprotection data beyond two years after the first booster
18 years – 64 years	Same as 2m – 18 years	A second booster dose (4th dose) should be offered at 10 years to those who remain at risk
>65 years	Booster dose at 12 months should be considered for those at continued / further risk.	The length of protection following a booster dose (3rd dose) is not known.

Who should be immunised?

1. JE vaccine is recommended for those going to reside in an area where JE is endemic or epidemic.

Staying for a month or longer	Travellers to South and South-East Asia and the Far East should be immunised if staying for a month or longer in endemic areas during the transmission season, especially if travel will include rural areas.
Staying for a shorter duration	Should be immunised if the risk is considered sufficient. For example, those spending a short period of time in rice fields (where the mosquito vector breeds) or close to pig farming.

Mention consulting http://travelhealthpro.org.uk/, www.nathnac.org and www.travax.nhs.uk.

2. Laboratory workers:

Immunisation is recommended for all research laboratory staff who have potential exposure
to the virus.

Contraindication and precaution

• Contraindication: A confirmed anaphylactic or serious systemic reaction to a previous dose of the IXIARO® vaccine or its component(s) (e.g. protamine sulfate).
• Precaution: Pregnancy and breastfeeding; a risk assessment should be done.

Adverse effect

• Pain, tenderness, erythema, hardening, swelling and itching at the injection site.
• Influenza-like illness, fever, headache, fatigue and myalgia.