The work deals with the results of the comparative evaluation of the effectiveness of
vaccines developed at the Sanitary Research Institute (Zagorsk) and the Mechnikov Research Institute for
Vaccines and Sera (Moscow), as well as two methods of immunization against
plague, by inhalation and
subcutaneous injection, under the conditions of
aerosol infection. The immunogenic effectiveness of both
vaccines, when evaluated in terms of LD50, was shown to be approximately the same, but the animals immunized by the inhalation method with the
vaccine developed at the Sanitary Research Institute proved to be less susceptible to
infection than those immunized with the
vaccine developed at the Mechnikov Research Institute for
Vaccines and Sera in Moscow. After immunization by the inhalation method the
vaccine developed at the Sanitary Research Institute rendered more effective protection (3- to 4-fold) against
aerosol infection than after immunization by
subcutaneous injection. The animals immunized by the inhalation method proved to be capable of surviving
plague in the primary pneumonic form.