Viral Vaccines: The Question of Revaccination

Abstract

With the increasing use of live virus vaccines, including those for measles, rubella, and mumps, the question is being raised as to whether or not revaccination will be necessary. Yellow fever vaccine, the prototype of live virus vaccines that are inoculated subcutaneously, produces persistent antibody titers, and a need for revaccination has not been established. If the newer vaccines are equally effective, then booster vaccination may not be required. Two other live virus vaccines that are not given subcutaneously are in current usage: (1) vaccinia virus, which is inoculated intradermally to prevent smallpox; and (2) poliovirus vaccine, which is given orally. Unlike the other live virus vaccines, the origin of vaccinia virus is uncertain, although it is related to smallpox virus. The immunity resulting from vaccinia virus appears to decrease with time, and clinical smallpox has been reported in previously vaccinated individuals. Poliovirus vaccine provides long-lasting immunity, so that the