Source:http://linkedlifedata.com/resource/umls/id/C1516086
NCI: Live vaccines prepared from microorganisms which have undergone physical adaptation (e.g., by radiation or temperature conditioning) or serial passage in laboratory animal hosts or infected tissue/cell cultures, in order to produce avirulent mutant strains capable of inducing protective immunity. Live-attenuated vaccines are used when a CD8+ T Cell (cellular cytotoxicity) response is desired.