Response to Booster Doses of Hepatitis B Vaccine among Young Adults Who Had Received Neonatal Vaccination

BACKGROUND Newborns who have received hepatitis B immunization in 1980s are now young adults joining healthcare disciplines. The need for booster, pre- and post-booster checks becomes a practical question. AIMS The aim of this study is to refine the HBV vaccination policy for newly admitted students in the future. METHODS A prospective study on medical and nursing school entrants to evaluate hepatitis B serostatus and the response to booster doses among young adults. FINDINGS Among 212 students, 17-23-year-old, born after adoption of neonatal immunization, 2 (0.9%) were HBsAg positive, 40 (18.9%) were anti-HBs positive. At 1 month after a single-dose booster for anti-HBs-negative students, 14.5% had anti-HBs <10 mIU/mL, 29.0% and 56.5% were 10-100 and >100 mIU/mL, respectively. The anti-HBs levels were significantly higher for females than males (mean [SD]: 431 [418] vs. 246 [339] mIU/mL, P = 0.047). At 2-4 month after the third booster dose, 97.1% had anti-HBs >100 mIU/mL and 2.9% had 10-100 mIU/mL. CONCLUSIONS Pre-booster check is still worthwhile to identify carriers among newly recruited healthcare workers born after adoption of neonatal immunization. A 3-dose booster, rather than a single dose, is required for the majority to achieve an anti-HBs level >100 mIU/mL, as memory immunity has declined in a substantial proportion of individuals. Cost-effectiveness of post-booster check for anti-HBs is low and should be further evaluated based on contextual specific utilization of results.