Hepatitis B vaccination in mentally retarded: Effectiveness after 11 years

The long-term effectiveness of hepatitis B vaccination was determined in a high-risk group of 105 institutionalized mentally retarded. All individuals were vaccinated in 1986, with three (0, I, 6 months), four (0, 1, 6 and 13 months) or more doses according to their immune response at month 7, resul ting in group 1 (G1), group 2 (G2) and group 3 (G3). They were annually fol lowed up for five years, after which they received a booster dose. Eleven y ears after the initial vaccination, they were again tested for the presence of hepatitis B virus (HBV) serologic markers. The decline in anti-HBs logt itre over the first five years was 51% for G1 and 45% for G2. From the boos ter on month 60 to year Il, the overall decline was 31%. Eleven years after the start of vaccination and six years after the booster, 92% of the indiv iduals had protective antibody levels higher than 10 IU/L. G1 had a geometr ic mean titre of 2015 IU/L, For G3 this was 245 IU/L. The difference in res ponse to vaccination between the groups did not affect their protection. On ly two vaccinees seroconverted to anti-HBc positivity without becoming carr ier or ill. Long-term protection against HBV by vaccination appears to be e xcellent. (C) 1999 Elsevier Science Ltd. All rights reserved.