Immune response and immunologic memory in medical personnel vaccinated with hepatitis B vaccine

The occupation-related nature of Hepatitis B viral infection in medical personnel has been well documented in a lot of studies. The only reliable way of prevention of this infection is immunisation with hepatitis B vaccine. To follow-up the primary immune response after immunisation with recombinant vaccine and its duration in adult immunocompetent subjects. One hundred sixty-five health-care workers working at St. George University Hospital, Plovdiv in 2009/2010 were included in the study and allocated to two groups. Group 1 (N1 = 70) was followed up for the primary immune response after immunization; group 2 (N2 = 95) was with documented immunization in 1998/1999 (n = 81) and in 1994/1995 (n = 14). Tests based on ELISA for quantitative determination of anti-HBs in mIU/ml were used. The measurement were performed at the National Reference Laboratory of Viral Hepatitis at the NCIPD, Sofia. Descriptive statistics, non-parametric and parametric tests, qualitative correlation were used to analyse data. Group 1 mean age was 40.3 +/- 2.6 years; anti-HBs concentration of > or = 10 mIU/ ml was found in 92.8%. No association between the immune response and the commonly involved factors such as gender, age, overweight, smoking, etc., was found. In group 2, anti-HBs concentration of > or = 10 mIU/ml was found in 77.9%: it was in 75.3% in those immunized 10 years before, and in 92.9% in those immunized 15 years before (t = 0.24, p > 0.05). A booster dose of the vaccine was received by 15/21 subjects from group 2 (those immunized 10 years before that) with anti-HBs < 10 mIU/ml. After the booster, 9/15 produced anti-HBs in protective concentrations (anamnestic immune response). The actual level of seroprotection among the immunized more than 10 years ago was 92%. This study and the documentation of the primary postvaccinal immunity in high-risk medical personnel will help specify if additional hepatitis B vaccine shots are needed.