[The immunogenicity of the vaccine against the HBV in the mentally retarded].

Our group carried out during 1989 a serological cross sectional study in 1,024 mentally handicapped patients (231 with Down's syndrome [DS] and 793 affected with other mental disturbances [OMD]), educated in seven institutions of the Madrid region. Those patients with negative HBsAg and anti-HBc markers were considered vaccination susceptible individuals. This group was constituted by 546 individuals. The regime of vaccination used was 0-1-6 m, and the dose, 20 micrograms i.m. The present study makes an evaluation of the postvaccine serologic results one month after the third dose. It was considered the age, sex and if he or she suffers from Down's syndrome or not. Corresponding with these variables the seroconversion rate (percentage of patients with greater than or equal to 10 IU/l of anti-HBs) was determined as well as the geometric mean titer (GMT) of antibodies. The seroconversion rate was 97.1% in the group affected with DS and 95.5% in the group with OMD, not being this difference statistically significant. There is not also significant association with regard to the sex, being the seroconversion rate in males (94.7%) and females (97.6%) very similar. However, it is significant difference between the mean age of the "responders" to the vaccine (24.6 years of age) and that of the "non responders" (33.3 years of age) (p less than 0.001). Thus, the age exerts a negative influence in the response to the vaccination. The titer of anti-HBs antibody, expressed using the GMT, has significant association with the sex (p less than 0.001) but not with the type of mental disturbance.(ABSTRACT TRUNCATED AT 250 WORDS)