Vaccination against poliomyelitis in Poland with types 1 and 3 attenuated viruses of Koprowski. 1. Virological studies of the vaccine strains and serological studies of the vaccinated population.

Mass vaccination of the juvenile population with live poliovirus vaccine was carried out in Poland in 1959 and 1960. In all, some 7 239 000 children 6 months to 14 years old were given type 1 (CHAT) virus, and nearly 6 818 500 children of the same age-group received type 3 (W-Fox) virus.A serological conversion rate (from <1:4 to >/=1:4) of 91.7% was achieved with type 1 and of 91.0% with type 3-a satisfactory demonstration of the immunogenicity of the strains used. Although type 2 virus was not administered, seroconversion with this type occurred in 65.4%. This may have been caused by antigenic elements common to the three poliovirus types, and previous vaccination with Salk vaccine may also have been a contributory factor.The authors conclude that the mass vaccination described in this paper has created a highly immune population in Poland.