1 Professor and Chairman, Department of Pediatrics, New York University School of Medicine, 550 First Avenue, New York, New York, 10016
In the introduction to our article (Pediatrics, 34:795, 1964) it is clearly stated that one inoculation of live measles vaccine is the immunization of choice for infants over 9 months of age. This regimen has obvious advantages over the combined inactivated-live measles vaccination procedures which entail multiple inoculations. On the other hand, live vaccine is not consistently immunogenic for younger infants because of the potential suppressive effect of residual passive antibody.
Passively acquired measles antibody may disappear as early as 3 months or as late as 11 months.