The immune response of healthy adults to a reduced dose of hepatitis B vaccine.

Three hundred thirty-six medical personnel from hemodialysis centers were treated with three doses, 20 microgram each, of the Merck hepatitis B vaccine (at 0, 1, and 6 months). Within 1 month after the first injection, 41% converted to anti-HBs positivity; after the second injection the conversion rate rose to 80-90%; and after the booster, to 96-98%. The later rate remained unchanged during the 18-month follow-up period. Only 2.8% of those vaccinated did not respond to the vaccine. The patterns of immune responses to 20-microgram doses were found to be exactly the same as to 40-microgram doses. It is suggested that reduced doses of vaccine should be as efficacious as the larger ones.