The responses of two rubella virus vaccine, live attenuated HPV-80 "vaccine failures" to intranasal challenge with low passage Brown stain of rubella virus were studied. Results indicated that "vaccine failures" shed live rubella virus from their pharynges for an extended period. These data are in contrast to those reported concerning reinfected vaccine-immunes. Further, following challenge, "vaccine failures" do not exhibit the signs and symptoms of clinical rubella. "Vaccine failures" may play a role in the transmission of this disease.
Wilkins J, Leedom JM, Portnoy B, Salvatore MA. Epidemiological Implications of Rubella "Vaccine Failures". Am J Dis Child. 1972;123(1):31-33. doi:10.1001/archpedi.1972.02110070081009