Measles in Children Previously Vaccinated Against Measles

Abstract

An outbreak of measles (rubeola) occurred in a city in northeastern Ohio between January and June 1969, involving 14 children previously inoculated with live attenuated measles virus vaccine and 46 unvaccinated children. In a school where the attack rate was 52.4% for unvaccinated children, the attack rate for children vaccinated by one particular physician was 17.9%, compared with 1.2% for children vaccinated by the local health department and other physicians. Vaccine in this physician's office was exposed to temperatures that may have contributed to virus inactivation. This study is an example of vaccine efficacy under conditions of current community use that is less than anticipated by field trial experience. Lack of initial seroconversion is the most likely cause of these vaccine failures and deterioration of vaccine infectivity during storage is proposed as the probable explanation.