Seroimmunity to poliomyelitis in an American community.

In an effort to determine the immune status of individuals in a natural community, neutralizing antibody titers for the three types of poliovirus were examined in 301 randomly sampled sera collected in 1966 and 308 specimens from 1971. The specimens were part of a larger collection obtained from residents of Tecumseh, Michigan. Approximately 22 sera from each five-year age group between 5-70 years were tested. A somewhat smaller number from younger and older individuals were also studied. Geometric mean titers for the two years of collection were in general quite low and never exceeded 1:42 which was found for type II virus. All GM titers decreased markedly as the age of the subjects increased. The percentage of individuals lacking antibody at the 1:4 level to at least one type of poliovirus ranged between 20-30% until age 49 and then steadily increased to over 60% in the 60-69 and over 70-year groups. A retrospective history of vaccination was obtained from 264 of the 308 persons in the 1971 collection. As expected these showed rather poor correlation with the presence or absence of antibody and were considered to be unsatisfactory as an index of immunity.