Experiences Associated with the Use of Live Poliovirus Vaccine in Hungary, 1959–1982

Live Sabin poliomyelitis vaccine has been given in Hungary since December 1959. Generally, monovalent vaccines--administered in the sequence type 1, 3, and 2--have been used in annually repeated nationwide campaigns. Each type was administered within a week all over the country, with an interval of five to eight weeks between administrations. In the initial campaigns, children younger than 14 years of age were vaccinated. Since 1962, children between two and 38 months of age have been vaccinated annually. As a result of the vaccination program, the mean annual incidence of poliomyelitis declined to 0.03 per 100,000 population between 1961 and 1982 from a level of 12 per 100,000 observed over the previous five years. Epidemiologic and virologic evidence indicated that 47 (82%) of 57 cases registered since 1961 were vaccine-associated. Circumstances connected with the special vaccination practice in Hungary gave an opportunity to estimate the risk of vaccine-associated poliomyelitis. For recipients receiving the vaccine for the first time, the estimated risks for each type of vaccine were type 1, 0.99; type 2, 0.65; and type 3, 8.91 per million and for susceptible contacts, type 1, 0; type 2, 3.62; and type 3, 4.97 per million. The author's opinion is that these rates of risk are acceptable in view of the benefits provided by the live vaccine, especially under circumstances when importation of wild polioviruses that circulate widely in extended regions of the world may commonly occur.