IN 1966, clinical trials demonstrated that a rubella virus modified by 77 passages in African green monkey kidney cultures (GMK) was attenuated for man.1,2 This strain (HPV-77) produced asymptomatic immunizing infections that were not communicable to contacts. The HPV-77 could be recovered from the respiratory secretions of recipients, and the vaccine induced levels of antibodies averaged six-to eightfold lower than in children convalescent from natural rubella. Most clinical trials were conducted in children and adolescents. Extending those experiences, the present report describes our experience with HPV-77 strain administered to infants.
Materials and Methods
Study Population and Experimental Design.—Infants from 5 to 12 months of age living in a public nursery were chosen to take part in this trial. Before admission to isolation unit each one was screened for susceptibility to rubella. Those having no detectable hemagglutination-inhibiting (HI) antibodies at 1:5 dilution and no neutralizing (NT) antibodies at