Enterovirus Survey in Children after Mass Vaccination with Live Attenuated Polioviruses

In Hungary three campaigns of oral immunization with Sabin's attenuated poliovirus strains were carried out in the period November, 1959, to June, 1960.(1) During November and December, 1959, the children aged 3 months to 14 years were twice fed with the trivalent vaccine in a single county (Gyor-Sopron county).(2) During December, 1959, to February, 1960, the children of the same ages were immunized in the whole country separately with types 1, 3, and 2 at monthly intervals.(3) The children who had escaped vaccination and the infants born between September 1, 1959, and February 29, 1960, were twice fed with the trivalent vaccine during May and June, 1960.The results of the serological and virological examinations carried out in several laboratories of specimens collected during the above campaigns were favourable (Weissfeiler, 1961).In this paper we present further data on the effectiveness of the mass oral vaccinations.The enterovirus excretion of the youngest healthy children was tested during the summer and early autumn of 1960-that is, during the season when the excretion rate of entero- viruses is usually the highest.We wished to see whether polioviruses were circulating in the population.In addition, the immune status of young children was examined six to eight months after vaccination.