THE LONG-TERM IMMUNITY AMONG HEALTH CARE WORKERS VACCINATED AGAINST HEPATITIS B VIRUS IN A LARGE REFERRAL HOSPITAL IN SOUTHERN IRAN

Background: Health care workers are at increased risk of occupational exposure to hepatitis B virus (HBV) infection. Reassessment for revaccination of such high-risk persons after 10 years may be appropriate if anti-HBs antibody titers declined below 10 mIU/mL. This study was conducted to evaluate the long-term efficacy of HBV vaccine in health care workers and the need for their reassessment for revaccination. Methods: We interviewed 600 health care workers in a referral hospital in Shiraz, southern Iran. They were asked to complete a confidential questionnaire including information on their age, gender, vaccination date, number of doses of vaccine, their job description in hospital, previous history of needlestick injury, and educational level. Anti-HBs antibodies were determined by the ELISA method and titers of >10 mIU/mL were considered protective. Those with a positive HBsAg or anti-HBcAb were excluded from the study. Results: Among 600 health care workers interviewed, 339 subjects who accepted to participate in the study, were vaccinated with three doses of HBV vaccine. Anti-HBsAb titers were >100 mlU/mL in 211 subjects (62.2%), 10 – 100 mlU/mL in 85 (25.1%), and <10 mIU/mL in 43 (12.7%) persons. Among 339 subjects who received three doses of vaccine, 273 were vaccinated less than 5 years, 47 cases between 5 – 10 years, and 19 cases were vaccinated more than 10 years before the study. The majority of them had an antibody concentration above the protective level (88.1%, 88.9%, and 60.9%, respectively, P = 0.001). Conclusion: Reassessment for revaccination in health care workers should be considered according to their anti-HBsAb levels 10 years after vaccination. In our health care workers, we think that due to the existence of low immunity against HBV, reassessment for revaccination after 10 years is mandatory.