High Effectiveness of Aerosolized Chick Embryo Fibroblast Measles Vaccine in Seven-Month-Old and Older Infants

Neither the presence of hypertonic sugar nor the absence of 1% human albumin in the aerosolized chick embryo fibroblast (CEF) measles vaccine was previously found to be responsible for its inadequacy in infants with titers of maternal plaque-neutralizing (PN) antibody at which human diploid cell measles vaccine was immunogenic. Eight weeks after administration of CEF measles vaccine containing 1% human albumin, antibody had developed in all 10 infants 7–10 months old and all 11 children 12–35 months old but in only 26% of 23 infants 3–5 months old and 67% of 9 infants 6 momhs of age. Failure of antibody development was associated with prevaccination PN antibody titers of 〉/1:50 (with one exception at a titer of 1:25). The PN antibody response to CEF vaccine (diluted 1:10, ∼105 pfu/ml) in infants under seven months of age (geometric mean titer [GMT], 1:421) was significantly lower (P