SEROCONVERSION AFTER ADDITIONAL VACCINE DOSES TO NONRESPONDERS TO 3 DOSES OF INTRADERMALLY OR INTRAMUSCULARLY ADMINISTERED RECOMBINANT HEPATITIS-B VACCINE

Hospital staff members who failed to respond (anti-HBs < 10 IU/l) after 3 doses of a recombinant hepatitis B (HBV) vaccine (given either as 20 mu g intramuscularly (n = 8) or 2 mu g intradermally (n = 15)) received 1 or 2 additional doses by the same route as the initial vaccination. After the first additional dose, 12/23 responded with anti-HBs levels greater than or equal to 10 IU/l and after the second, another 2/5 responded, corresponding to a total response rate of 61%. No significant difference was seen in the response rate according to vaccination route, gender, age, or whether the vaccinee was a smoker or not. In this limited study some 50% of non-responders to 3 intradermal or intramuscular doses of recombinant HBV vaccine seroconverted after an additional 1-2 doses given by the same route as the initial, vaccination, suggesting that additional doses can be administered by the same route as the initial one.