Diploid Cell Measles Vaccine

To the Editor.— Dr Albert Sabin and one of us (J.F.D.)1,2recently reported seroconversion in infants administered measles vaccine of human diploid cells (HDCs) that contained the Ikić (Edmonston-Zagreb) strain and 1% human albumin, or chick embryo fibroblast (CEF) vaccine that contained the Edmonston-Schwartz strain by cutaneous or aerosol routes. In that study, we used enzyme-linked immunosorbent assay and plaque neutralization tests to demonstrate seroconversion. In this letter we report a further study inwhich antibody was measured using the more standard hemagglutination inhibition. This double-blind study was carried out in children aged 6 to 8 months residing in two poor urban areas of Mexico City between October 1983 and April 1984. Report of a Case.— One hundred seventy-two children received HDC vaccine manufactured in Mexico: 117 via aerosol (titer of virus, 105.250% tissue culture infective dose per milliliter), and 55 by injection (titer of virus, 10