Hepatitis B Vaccine Response in Children of Vaccinated Versus Unvaccinated Mothers: A Retrospective Cohort Study

Universal infant hepatitis B (HBV) vaccination is highly effective in preventing infection. However, little is known about whether a mother's HBV vaccination history influences her child's immune response to routine immunisation. We aimed to compare vaccine-induced antibody responses in children of vaccinated and unvaccinated mothers. We conducted a historical-retrospective cohort study of 364 children who completed the standard infant HBV vaccination series and underwent post-vaccination antibody testing. Maternal vaccination status was determined by serology, medical records and cohort year. Children were classified as offspring of HBsAg-negative vaccinated mothers (n = 92), HBsAg-negative unvaccinated mothers (n = 174), or HBsAg-positive mothers (n = 98), who also received hepatitis B immunoglobulin (HBIG) at birth. Anti-HBs titers were analysed and categorised. Ordinal logistic regression was used to assess associations. Overall seroprotection rates (≥ 10 mIU/mL) were high (89.3%) and did not differ significantly between groups. However, children born to mothers vaccinated prior to pregnancy were significantly more likely to achieve very high antibody levels (≥ 1000 mIU/mL) compared with children of unvaccinated mothers or those who received HBIG at birth (p < 0.05). This association was most pronounced in children tested at ≤ 3 years of age. Mean anti-HBs titers were also highest in offspring of vaccinated mothers. While older maternal age and lower haemoglobin levels impaired the response, the HBIG did nothing. While infant HBV seroprotection rates were uniformly high regardless of maternal background, children born to mothers vaccinated against HBV prior to pregnancy exhibited a more robust early antibody response (≥ 1000 mIU/mL). These findings suggest a possible intergenerational enhancement of vaccine responsiveness and may affect long-term implications for HBV vaccination strategies.