Altered reactivity to measles virus. Local reactions following attenuated measles virus immunization in children who previously received a combination of inactivated and attenuated vaccines.

MEASLES immunization is an accepted pediatric preventive measure. Several different immunizing procedures have been recommended, including: (1) attenuated virus administration with and without simultaneous immune globulin; (2) a series of inactivated vaccine injections; and (3) combinations of attenuated and inactivated virus. 1,2 Attenuated virus immunization is safe, evokes serum neutralizing antibody in 95% or more of susceptible children, and confers long-lasting, probably lifelong, immunity. 3 Immunization with inactivated vaccine has not resulted in similar protection; neutralizing antibody is stimulated in 90% of patients, but is relatively short-lived. More important, immunity wanes, resulting in modified or typical measles upon natural exposure. 4-7 Sufficient data has not been accumulated to make a final judgment of the combined inactivated-attenuated virus vaccine schedule. The administration of inactivated vaccine in one or more doses preceding attenuated virus administration results in diminished fever and rash and in adequate antibody stimulation. 4,6 However, some individuals with demonstrable