Armstrong – Table of Contents

research and academic communities. Dr. Salk succeeded in developing a killed polio
vaccine containing the three immunologic types. Dr. Thomas Francis, Jr. of the
University of Michigan, who had been Dr. Salk’s early research mentor, conducted and
oversaw a successful, controlled field trial of the vaccine starting April 1954. On April
12, 1955 before an enthusiastic audience of investigators, politicians, and members of the
press, Dr. Francis, representing the Polio Vaccine Evaluation Center at the University of
Michigan, pronounced the Salk vaccine to be effective and safe. The United States
government licensed the vaccine for use almost immediately, and the National
Foundation launched a program of free vaccination for school children in the first and
second grades. Shortly after initiation, the program had to be cancelled abruptly because
batches of vaccine from the Cutter Laboratories were causing clinical poliomyelitis. After
much consultation with the Public Health Service, polio investigators and the re-
evaluation of manufacturing standards for safety, the program resumed, and a large
percentage of the population received immunization with the Salk vaccine.
A different approach to polio immunization was the effort by Dr. Albert Sabin
(and others) to prevent infection by immunizing the alimentary tract using attenuated
polio strains that had lost their ability to grow in the central nervous system. Sabin
developed his vaccine strains during the 1950s and early 1960s. In view of the success of
the Salk vaccine by this time period, most of the field trials with the oral polio vaccines
occurred in the Soviet Union where large susceptible populations could be immunized
within short periods. By the mid-1960s the Sabin oral polio vaccines supplanted the Salk
vaccine for routine immunization in the United States, and they helped eliminate polio
from the Western Hemisphere and many parts of the developing world. However, a slight