By the time Dr. Jonas Salk developed the first successful vaccine for the poliovirus in 1952, the polio epidemic had reached a peak in the United States with more than 21,000 paralytic cases, according to the Centers for Disease Control and Prevention (CDC).1 Less than a decade later, in 1960, the number of paralytic polio cases in the U.S. had been reduced to about 2,500. Five years later, there were just 61. In 1994, just 42 years after Salk introduced his vaccine, polio was declared eradicated from the Americas.
Before Salk made his breakthrough, parents across America were terrified that their children would contract the disease, and physicians were desperate for preventive or therapeutic measures. Despite this pressure, Salk conducted a textbook case of careful research. He began his poliovirus research in 1947 and published his findings in the Journal of the American Medical Association in 1953. The following year, testing for the Salk vaccine began in the largest clinical field trials ever conducted in U.S. history. Led by Thomas Francis, Jr., of the University of Michigan, the trials included children in communities throughout the U.S. and parts of Canada.2 In the vaccinated test groups, polio cases fell dramatically. Just one year later, in 1955, the federal government approved the vaccine for distribution to children. In 1963, a live oral form of vaccine developed by Albert Bruce Sabin was also approved. Even today, children receive the polio vaccine because the disease is still found in certain parts of the world.
In the annals of medical history, the Salk polio vaccine stands as an example of one of the fastest and most successful adoptions of a medical practice based on scientific evidence, even though it long preceded the formal use of the term “evidence-based medicine.” It clearly demonstrates the essence of what evidence-based medicine is: care based on evidence from carefully designed research studies.