In a probabilistic sample of the elementary school children belonging to the S. Paulo public school system, a survey was conducted in order to establish 1) the vaccination status of the children - number of doses of oral polio vaccine, 2) the kind of housing - private home or slum, 3) the cultural status of the mother - literate or illiterate. These factors were studied in relation to the prevalence of neutralizing antibodies and the immune status to poliomyelitis of those children. The results showed a correlation between the presence of type 1, 2 and 3 poliovirus antibodies and the number of doses of trivalent Sabin vaccine fed to children 7 and 8 years old, who exibited satisfactory immunity level only with 5 and more doses of the vaccine. In the age group of 9 to 15 years and higher, the immune status of the children was no more related to the number of doses of the vaccine which is considered as a result of the immunization of the children by means of natural infections with circulating polioviruses. When the immune status of the children was related to housing and the cultural level of the mother, the relationship described for certain age groups (7 and 8 years) was not observed, which seems to be explained by the same reasons refered to the 9 to 15 and higher age groups. The authors recommended that the primary course of immunization for infants should consist of at least 5 doses of trivalent Sabin vaccine.
Serological surveys; Poliomyelitis; Immunity; Poliovirus vaccine
