OBJECTIVES: 1) To determine the persistence of vaccine-induced antibody from various rubella vaccines by measuring serum hemagglutination inhibition antibody in rubella vaccinees up to 15 years after vaccination. 2) To determine the effect of revaccination in rubella vaccinees who no longer have detectable vaccine-induced antibody. 3) To determine protection to experimental rubella virus challenge in rubella vaccinees who no longer have detectable vaccine-induced antibody. To determine if protection is afforded by specific rubella cell-mediated immunity or rapid recall of serum antibody. 4) To determine the protective effect of cell-mediated immunity to rubella challenge in ferrets.