Immune response to hepatitis B revaccination.

Two hundred and twelve individuals who failed to respond or responded poorly to hepatitis B vaccination or whose anti-HBs levels had dropped below 10 IU/L at follow-up were revaccinated. Only 18% of initial nonresponders, but 96% of those who responded initially, developed anti-HBs above 10 IU/L after revaccination. In 85% of vaccinees, anti-HBs titres after a fourth immunization were significantly higher than after completion of the first full immunization course, and despite a steeper decline of antibody levels after revaccination, anti-HBs seemed to persist better than after the initial course of three inoculations. All individuals who responded initially and in whom anti-HBs had become undetectable developed antibodies. Response to booster doses was seen after three to five days, and a fifth inoculation given to 23 individuals induced even better responses.