[Development of immunity to the poliomyelitis virus in infants with various methods of administering a live poliomyelitis vaccine].

The data have been obtained which indicate that the effectiveness of vaccination with live trivalent poliomyelitis vaccine may be increased and 90--100% of the vaccinated infants under 1 year of age may develop marked resistance of the alimentary tract and high antibody titers in the blood serum to the threee types of poliomyelitis virus in the course of 3 vaccinations. Some regularities of the formation of immunity to individual poliomyelitis virus types in the course of 4 vaccinations with trivalent vaccine were revealed and specified. The results indicate that the contact of vaccine virus with the oropharyngeal tissues during immunization has a favourable effect on the development of immunity. Vaccination of infants under 1 at 6-week intervals between vaccine feedings creates solid immunity in 90--100% vaccines. Administration of the next vaccine dose 6 weeks after the previous one stops multiplication of the dominating type of vaccine virus and prevents its long-term passage in the intestinal tract decreasing the probability of emergence of vaccine virus variants with increased pathogenicity.