The polio vaccine began to be widely used in 1955. The table shows number of cases generally declining after widespread use of the vaccine in 1955. An upswing in 1959 may have been due to a natural periodic epidemic year of polio, which had occurred in the past every few years.
The Historical Medical Library of The College of Physicians of Philadelphia. Poliomyelitis. U.S. Department of Health, Education, and Welfare. Public Health Service. Health Information Series, No. 8. Public Health Service Publication No. 74. Rev. 1963.
The Historical Medical Library of The College of Physicians of Philadelphia