Antibody Levels and Protection after Hepatitis B Vaccine: Results of a 22-Year Follow-Up Study and Response to a Booster Dose

Background. The duration of protection in children and adults (including health care workers) resulting from the hepatitis B vaccine primary series is unknown. Methods. To determine the protection afforded by hepatitis B vaccine, Alaska Native persons who had received plasma-derived hepatitis B vaccine when they were > 6 months of age were tested for antibody to hepatitis B surface antigen (anti-HBs) 22 years later. Those with levels < 10 mIU/mL received 1 dose of recombinant hepatitis B vaccine and were evaluated on the basis of anti-HBs measurements at 10-14 days, 30-60 days, and 1 year. Results. Of 493 participants, 60% (298) had an anti-HBs level >= 10 mIU/mL. A booster dose was administered to 164 persons, and 77% responded with an anti-HBs level >= 10 mIU/mL at 10-14 days, reaching 81% by 60 days. Response to a booster dose was positively correlated with younger age, peak anti-HBs response after primary vaccination, and the presence of detectable anti-HBs before boosting. Considering persons with an anti-HBs level >= 10 mIU/mL at 22 years and those who responded to the booster dose, protection was demonstrated in 87% of the participants. No new acute or chronic hepatitis B virus infections were identified. Conclusions. The protection afforded by primary immunization with plasma-derived hepatitis B vaccine during childhood and adulthood lasts at least 22 years. Booster doses are not needed.