First decade (1950-1960) of studies and trials with the polio vaccine.

The chronology of the development of polio vaccines following the first human trials of attenuated poliovirus vaccine in 1950 is described by me as a witness to the first decade of trials and tribulations following my discovery of polio vaccine in 1950. Mass vaccination trials are considered to be the most important phase of the discovery of oral polio vaccine (OPV). These took place in the Belgian Congo, Poland, Croatia, Switzerland, and finally in the former Soviet Union. By 1960, approximately 13 million individuals had been vaccinated with the Koprowski oral polio vaccine and over 11 million with the Sabin vaccine.