FURTHER STUDIES OF AN ATTENUATED RUBELLA STRAIN GROWN IN WI-38 CELLS

A rubella virus strain, RA27/3, previously attenuated by 25 passages in the WI-38 human embryo lung fibroblast cell strain, was submitted to further clinical testing. Groups of seronegative subjects were inoculated subcutaneously with the 26th, 27th or 30th WI-38 passage level material and observed for clinical reaction and for antibody response. Seronegative contacts served as controls for contagiousness of vaccine. No clinical reaction was noted except slight lymph node enlargement in some vaccinees. Nearly all of the vaccinees developed significant levels of rubella antibody. Contacts of vaccinees, including siblings and adults exposed within families, failed to show evidence of infection.