[Long-term effect of oral immunization against influenza with a live vaccine in mice].

NMRI-mice were immunized orally twice within 19 days with live influenza virus (A/PR/8/34). Immunization led to the occurrence of specific antibodies in the respiratory tract detectable at least for 6 months after booster immunization. Immunized animals are protected against aerogenic infection, demonstrable by normal lung cell yield, lack of virus shedding, and survival of all mice. The used doses was lethal for unimmunized controls.