Comparative genotoxicity of halogenated acetic acids found in drinking water

20 years after the introduction of the hepatitis-B vaccine the question still remains unsolved as to how the 2 to 5 per cent of the vaccinees who, after basic immunisation, respond with no anti-HBs levels (0-10 IU/l nonresponder, NR) or low levels (11-99 IU/l low-responder, LR) should be boostered to acquire sufficient and long-lasting protective anti-HBs levels. In a retrospective analysis of booster results we found in 75 NR and LR that the probability for long-lasting protection is very low for NR, but better for LR (60%). In a second part of this publication, the efficacy of intradermal and intramuscular hepatitis-B boosters was examined by retrospective analysis of booster results among 26 NR and LR. A slight advantage of the intradermal application was found concerning post-booster anti-HBs increase and the maximal HBs values reached. Long-lasting protective anti-HBs values could not be established for either way of application. Finally, a survey of the literature summing up true results of intradermal hepatitis-B basic immunisations with reduced doses (mostly 2 micrograms), shows that whereas the seroconversion rates achieved by this method are almost compatible with those after regular basic vaccination, the GMT values were far lower than those after regular basic vaccination. Prospective and randomised studies are needed to show which kind of booster is most efficient for nonresponders and low-responders.