Characteristics of the dynamics of herd immunity to the poliovirus and of the quality of the vaccination carried out against poliomyelitis

: The aim of this work was to study the state of immunity in children immunized with liquid poliomyelitis vaccine. During 1976-1981 the intensity of immunity to poliomyelitis in 653 children aged 1-3 years was studied. The study showed that at the period when liquid poliomyelitis vaccine was used the share immune to polioviruses, types 1 and 2, constituted 89.4% and 98.0%, respectively, as compared with 67.0% and 68.0% at the period when sugar-coated live dried poliomyelitis vaccine was administered. Changes in such epidemiological characteristics, as the percentage of persons with antibodies to poliovirus, were particularly essential in the age group of 1-2 years. In 1979 persons with antibodies to type 1 poliovirus constituted 94.0% as compared with 44.0% in 1976, while the percentage of persons found to be seronegative in respect of antibodies to polioviruses, types 1, 2 and 3, decreased 5-7 times. The quality of immunization carried out at the period, when liquid poliomyelitis vaccine was used, was shown to influence the size of the immune share, while having no effect on the geometric mean of the titer of antibodies to polioviruses.