Multiple virus vaccines and the interference phenomena

: It is well known that interference between two viruses simultaneously infecting the same host may bring about the exclusion of one. When administering attenuated viruses for immunization purposes this fact should be theoretically taken into account. The present tendency of associating attenuated virus into multiple vaccines (trivalent polio, mumps-rubella-measles) is supported by their proved effectiveness. The reasons of the non-operativity of the interference mechanism in such conditions are discussed.