Investigation of 37 cases of measles in an Alabama elementary school revealed that 25 patients (68%) had been vaccinated, suggesting measles vaccine failure. Attack rates based on a measles history and immunization survey indicated that 16.2% (six of 37) of measles susceptibles who responded acquired disease compared with only 4.0% (20 of 505) of vaccinated respondents. Analysis showed that 17.6% (12 of 68) of children vaccinated at less than 12 months of age contracted measles compared with only 1.9% (eight of 419) of those vaccinated at 12 or more months of age. It is inferred that vaccination at less than 1 year of age may not be effective, because maternal antibody may persist and interfere with immune response to vaccine virus. This would explain the higher incidence in this epidemic of measles among children vaccinated as infants.
Currier RW, Hardy GE, Conrad JL. Measles in Previously Vaccinated ChildrenEvaluation of an Outbreak. Am J Dis Child. 1972;124(6):854–857. doi:10.1001/archpedi.1972.02110180056007