Efficacy of hepatitis B surface antigen vaccination of Japanese healthcare workers and the importance of immunosurveillance

Back ground and object: Healthcare workers are at excess risk for HBV infection because of their occupational exposure to potentially infectious body fluids from patients with chronic HBV infection. This study was performed to assess the efficacy with HBV surface antigen (HBsAg) of booster vaccinations after primary immunization in Japanese healthcare workers. Methods: We determined the anti-HBV surface antigen (HBs) levels of 469 Japanese healthcare workers who had received three or more booster vaccinations with HBsAg vaccine and had become immunized. These subjects were followed up for two years. Results: At follow up, 415 subjects were positive (≥10 mIU/ml) and 54 were negative (<10 mIU/ml). The subjects with higher anti-HBs levels at baseline showed higher anti-HBs levels at follow-up (p<0.001). Of these 54subjects, three had retired, and the remaining 51 were given one additional booster dose of the vaccine. Age-related differences were not observed. All subjects who received one booster dose of vaccination achieved an anti-HBslevel≥10mIU/ml. Conclusion: Although the efficacy of the HBsAg vaccine was approximately 90% following a full course of immunization, immunity can be restored with another booster vaccination in the other 10%. These results indicate the importance of immunosurveillance of healthcare workers at appropriate times following HBsAg vaccination.