Live, Further Attenuated Rubeola Vaccine

Responses of infants have been studied following inoculation with live attenuated measles virus vaccine (Schwarz). Maximal responses occurred after 12 months of age regardless of birth weight. However, to achieve measles eradication, it may be desirable to immunize infants as young as 9 months of age. Quantitative differences in levels of antibody are recognized following acquired rubeola infection, and administration of attenuated and further attenuated rubeola virus vaccines. Since the latter, stimulating the lowest antibody levels, are now used almost exclusively, it is conceivable that in the future maternal antibody levels may be lower. Thus, passively acquired antibody levels in infants born of mothers with vaccine-induced immunity can be expected to decline to insignificant levels earlier in infancy. Active immunization may be feasible even earlier in infancy after the next decade.