Hepatitis B Surface Antibody Titers at One and Two Years after Hepatitis B Virus Vaccination in Healthy Young Japanese Adults

OBJECTIVE: Since healthcare providers face an increased risk of hepatitis B virus (HBV) infection because of their work, vaccination plays a critical role in preventing HBV transmission. However, the duration for which acquired HBV surface antibodies (anti-HBs) persist remains unknown. To evaluate the primary immunologic response to HBV vaccination and its persistence in healthy Japanese adolescents. METHODS: In total, 690 young adults underwent HBV vaccination with a three-dose schedule. The primary response was determined by the anti-HBs titers at 1-2 months after the final dosage. Subjects with anti-HBs titers of <10, 10-100, and >100 mIU/mL were classified as “non-responders,” “low-responders,” and “sufficient responders,” respectively. Anti-HB titers were re-measured at 1 or 2 years after vaccination. RESULTS: First, 95.8% and 72.8% of the subjects had anti-HBs titers of >10 and >100 mIU/mL, respectively, as a primary response. The anti-HBs titers measured at 1 and 2 years after vaccination were significantly correlated with those of the primary response (1 year: r=0.893, p<0.0001; 2 years: r=0.902, p<0.001). Most subjects with a titer of >100 mIU/mL at the primary response maintained an anti-HBs titer of >10 mIU/mL [1 year after vaccination, 208/209 (99.5%); 2 years after vaccination, 72/81 (90.1%)]. However, in subjects with a primary response of 10-100 mIU/mL the anti-HBs titer frequently declined; 17/38 (44.7%) and 9/10 (90.0%) subjects had a titer of <10 mIU/mL at 1 and 2 years, respectively. CONCLUSION: The primary response was associated with the anti-HBs titers at 1 and 2 years after vaccination, and the anti-HBs titers of 54.2% of the low responders were not maintained for 2 years, even if they were vaccinated as healthy young adults.