Hepatitis A Vaccine

Epidemiology And Rationale

Hepatitis A virus causes benign, asymptomatic infection in young children.
Disease severity and mortality increase significantly in adolescents and adults.
Shifting endemicity in India leaves older populations susceptible, contributing to recurring outbreaks and fulminant hepatic failure.

Feature	Inactivated Vaccine	Live Attenuated Vaccine
Viral strain	HM 175 or GBM strain	H2 or LA-1 strain
Adjuvant	Aluminum hydroxide or virosome	None
Route	Intramuscular	Subcutaneous
Schedule	Two doses	Single dose
Immunocompromised	Safe for use	Contraindicated
Available brands	Havrix, Avaxim, Hapibev, Havisure, Havpur	Biovac A

Minimum age for vaccination initiation remains 12 months.
Inactivated schedule entails two intramuscular doses administered 6 to 18 months apart.
Live attenuated schedule requires a single subcutaneous dose.
Catch-up vaccination requires pre-vaccination antibody screening for children older than 10 years due to high baseline seropositivity.
Protective threshold defined as antibody levels between 10 and 33 mIU/ml.
Both vaccine types generate long-lasting, possibly life-long protection without requiring routine boosters in immunocompetent individuals.

Vaccine administration preferred over immunoglobulin due to active immunity induction and longer protection.
Administer single vaccine dose within two weeks of exposure for contacts aged 1 to 40 years.
Administer intramuscular immunoglobulin for infants under 1 year and adults over 40 years.
Immunocompromised contacts require both vaccine and specific immunoglobulin.