History of poliomyelitis in the Czech Republic--Part III.

The "repression phase" of paralytic poliomyelitis in the Czech Republic (and in the Slovak Republic as well) between 1957 and 1960 was characterized by controlled, short term, mass vaccination campaigns. In spring 1957, at the very beginning of a polio epidemic, about 87% of all children aged 1 to 7 years and about 40% of those aged 8 to 15 years were intradermally vaccinated with IPV. The protective effect in population given two IPV doses was 66% (in Slovakia 74%). The starting epidemic of 1957 was stopped. Morbidity and mortality from poliomyelitis markedly decreased in 1958. Nevertheless, about 39%, 13% and 41% of children aged under 8 years (given three IPV doses) had not specific virus-neutralizing antibodies against polioviruses types 1, 2 and 3 respectively. A field trial with OPV started in winter 1958-59. Over 110,000 children aged 2 to 6 years were vaccinated with Sabin OPV, which proved to be safe, highly immunogenic and protective. In spring 1960 about 93% of children were vaccinated in the former Czechoslovakia with OPV in a mass, countrywide campaign. No case of paralytic poliomyelitis was reported during the second half of 1960. The same was true for all year 1961, the first year of the historical period of poliomyelitis elimination in our country.