A Summary of Field Experience with Live Virus Measles Vaccine

Abstract

Field trials of live measles virus vaccines in 15 different locations are discussed. Five different lots of lyophilized vaccine were used, all prepared from the Edmonston strain of virus. Titers of the vaccines varied from a minimum of 100 TCID50 to a maximum of 300,000 per ml. Clinical histories of 345 of the sero-negative children vaccinated were studied. Responses suggested that the frequency of severe reactions could be considerably reduced by limiting vaccination to the summer and autumn seasons. Infants one year of age or younger tolerated vaccination very well, and severe reactions among them were infrequent, but the number of successful responses in infants under 8 months of age is significantly reduced by residual maternal antibody. Because of the inhibiting effect of low levels of systemic antibody and the varying amounts of measles antibody present in pooled gamma globulin, the use of unstandardized antibody concentrates with measles vaccine requires careful study.