Measles CF and neutralizing antibody titers have been determined in approximately 300 serum specimens collected in the New Haven area. Antibodies were found in nearly all specimens from children with a history of measles and also, with a lower average titer, in 31% of children with negative histories.
Most specimens collected at birth contained antibodies. The proportion positive fell to a low point in the 1–4 year old group and then rose rapidly in the school age groups reaching more than 90% in the 8–9 year olds. This pattern of antibody development followed closely the age specific attack rate for reported cases. In children from whom histories were available no correlation was found between antibody titer and the length of time since the serum donor had had measles.
All adult age groups included 3–13% of individuals whose specimens gave negative reactions. The fraction of negative reactions did not change appreciably with increasing age but there was a gradual decrease in average titer in the adult age span.
The rate of antibody development was strongly influenced in preschool population groups by family size, but no relationship could be demonstrated between antibodies and class of housing.