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Will Infant Hepatitis B Vaccination Protect Into Adulthood?: Extended Canadian Experience After a 2-, 4- and 6-month
Michelle Pinto1, Meena Dawar, Mel Krajden
1From the *Vaccine Evaluation Center, Vancouver, British Columbia, Canada; †University of British Columbia, Vancouver, British Columbia, Canada; ‡Vancouver Coastal Health Authority, Vancouver, British Columbia, Canada; and §BC Centre for Disease Control, Vancouver, British Columbia, Canada.
Insights
Infant Hepatitis B virus (HBV) vaccination provides lasting immune memory in most adolescents, though antibody levels wane over time. Booster responses confirm protection, but further evaluation is needed for long-term efficacy.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Hepatitis B virus (HBV) vaccination is crucial for preventing chronic infection and transmission.
- Current programs target infants and preadolescents.
- This study assesses long-term immunity following infant HBV immunization in Canadian children.
Purpose of the Study:
- To evaluate residual immunity and immune memory 10-16 years after infant HBV vaccination.
- To determine if infant immunization alone can prevent chronic HBV infection and reduce adult transmission.
Main Methods:
- Prospective study of adolescents vaccinated in infancy (2, 4, 6 months).
- Anti-HBs antibody levels measured at 10-11 and 15-16 years of age.
- Vaccine challenge administered to participants with low antibody levels to assess immune memory.
Main Results:
- Most participants had low antibody levels (<12 mIU/mL) at follow-up (78% of 10-11 year olds, 64% of 15-16 year olds).
- Nearly all participants responded robustly to a vaccine challenge, indicating persistent immune memory.
- Anamnestic responses were stronger in younger adolescents (10-11 years) compared to older ones (15-16 years).
Conclusions:
- Infant HBV vaccination induces durable immune memory, with most adolescents retaining the ability to mount a protective response.
- Antibody levels decline over time, but immune memory persists.
- Booster responses were weaker in older adolescents, suggesting potential waning immunity and warranting extended evaluation.
Background:
Hepatitis B virus (HBV) vaccination programs generally target infants to prevent chronic HBV infection and/or preadolescents to reduce transmission in adulthood. To assess whether infant HBV immunization can potentially accomplish both objectives, we measured residual immunity 10-16 years after vaccination in Canadian children.
Methods:
A prospective, parallel group, single center study enrolled adolescents given HBV vaccine at 2, 4 and 6 months of age. Exclusion criteria included prior HBV infection and additional vaccinations. At follow-up anti-HBs testing, participants were 10-11 or 15-16 years old; those with <12 mIU/mL anti-HBs by the assay used were challenged with HBV vaccine to assess immune memory-based responsiveness.
Results:
A total of 137 tested participants were 10-11 and 213 were 15-16 years old, respectively; none had evidence of prior HBV infection. At baseline, 78% of younger and 64% of older participants had <12 mIU/mL anti-HBs (P = 0.006) and were challenged with vaccine: 103/106 (97.2%) younger and 123/135 (91.1%) older participants developed ≥12 mIU/mL anti-HBs (P = 0.06), with geometric mean antibody concentration of 590 (95% confidence interval: 473-737) and 319 mIU/mL (95% confidence interval: 229-445; P = 0.004), respectively. Immune memory loss may have occurred in 3 younger (2.2%) and 12 older children (5.6%; P = 0.06) who were nonresponsive to first but not second vaccine challenge.
Conclusions:
After HBV vaccination at 2, 4 and 6 months of age, most adolescents had little or no residual antibody but nearly all responded to HBV challenge, confirming immune memory persistence. However, anamnestic responses were weaker in 15- to 16-year olds and lost in some. Booster responses in 10- to 11-year olds were vigorous in comparison. Extended evaluation of protection is warranted.
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