Inadequate Poliovirus Immunity Levels in Immunized Illinois Children

Abstract

Antibody titers to poliovirus, measles, and rubella in 504 low-income children in six Illinois communities were compared with the immunization records of those children. Titers to measles and rubella were, as expected, nearly always present in immunized children, but only one third of children who had received three or more doses of live oral poliovirus vaccine (OPV) had measurable titers to all three polio types. Age, sex, race, age at first OPV, interval between OPVs, and time lapse since last OPV were not found to be significantly related to the absence of polio antibody in immunized children. We conclude that day-to-day immunization practices may result in different immunity levels than published field trial studies of the same vaccines indicate, and that continuing study of vaccine after licensure may be desirable.