Evaluation of the response to a booster dose of hepatitis B vaccine in previously immunized healthcare workers

Introduction: Hepatitis B vaccination is recommended for all healthcare wor kers (HCW) at risk of exposure to infectious body fluids. However, the abso lute duration of protection from immunization is unknown. The purpose of th is randomized comparison trial was to determine how previously immunized HC W respond to different booster doses of hepatitis B vaccine. Method: Adult HCW (n = 59) were classified by level of hepatitis B surface antigen (anti- HBs), either < 10 milli-International Units per milliliter (mIU/ml) or 10-5 0 mIU/ml. Participants were then randomized to receive a 2.5 or 10 mug dose of hepatitis B vaccine. Evaluation of anti-HBs levels were conducted 10 to 14 days, one month and one year postbooster. Results and discussion: All p articipants responded to the booster dose with increased anti-HBs levels. A t 14 days, mean anti-HBs levels were significantly higher for those with hi gher levels at baseline (P = 0.004) and those receiving the 10 mug dose (P = 0.016). At one month, those with higher anti-HBs levels at baseline and t hose receiving the 10 mug dose were significantly higher (P < 0.01 for both ). At one year, the increase for the higher dose was no longer statisticall y significant when examined by itself (P = 0.081); statistical significance (P = 0.021) was achieved after adjusting for anti-HBs level at baseline. F or all participants, the geometric mean anti-HBs level was 2618 mIU/ml at 1 4 days, 2175 mIU/ml at one month and 88.9 mIU/ml at one year. At all time p oints the increase in anti-HBs levels represented an increase over the geom etric mean baseline level of anti-HBs (7.4 mIU/ml). Hepatitis B immunized a dults responded to a booster dose of hepatitis B vaccine from 3 to 13 yr po stvaccination series. Data support current recommendations that immunized H CW do not require periodic antibody testing or vaccine boosters. (C) 2001 E lsevier Science Ltd. All rights reserved.