Question
Hepatitis B vaccine
Answer
Hepatitis B vaccine is a recombinant, subunit vaccine containing purified Hepatitis B surface antigen (HBsAg), produced by recombinant DNA technology (expressed in yeast, e.g., Saccharomyces cerevisiae) — one of the first widely used recombinant vaccines and highly effective at preventing HBV infection and its long-term complications (cirrhosis, hepatocellular carcinoma).
Schedule: given as part of the routine infant immunization schedule — a birth dose (within 24 hours of birth, particularly important for preventing perinatal transmission from HBsAg-positive mothers) followed by additional doses as part of the primary series (e.g., at 6, 10, and 14 weeks, often combined in the pentavalent vaccine in many national programmes, including India’s).
Mechanism: stimulates active production of anti-HBs antibody, providing protective immunity; being a subunit (non-live) vaccine, it carries no risk of causing HBV infection itself and is safe even in immunocompromised individuals.
High-risk group vaccination: recommended for healthcare workers, dialysis patients, household contacts of HBsAg-positive individuals, and other high-risk groups not covered by routine infant schedules.
Post-exposure prophylaxis: Hepatitis B Immunoglobulin (HBIG) plus vaccination is given to neonates born to HBsAg-positive mothers, and to individuals with high-risk needle-stick/mucosal exposure, combining immediate passive protection with the vaccine’s active, longer-term immunity.
Efficacy monitoring: anti-HBs antibody titre can be checked post-vaccination in high-risk groups (e.g., healthcare workers, dialysis patients) to confirm adequate seroconversion (a titre ≥10 mIU/mL is generally considered protective).