1954 Salk Vaccine Trial

In the years following World War II, polio (also known as poliomyelitis and infantile paralysis) reached epidemic levels in the United States, and by the 1950s, it had become America’s most dreaded infectious disease. In 1952, during the worst polio outbreak in U.S. history, nearly 58,000 people were infected, 21,000 were paralyzed, and 3,145 died, most of them young children.[1]

For a long time, no one knew how polio was transmitted. There was no known means of prevention, no cure, no way of telling who might get it and who would be spared.[2] People were afraid – afraid to let their children leave the house, go swimming or to the movies – or anywhere that people gathered.

President Franklin Delano Roosevelt contracted polio in 1921 at age 39; the disease completely paralyzed his legs. This personal experience and his own lifelong disability gave him a special interest in finding a cure for polio. Roosevelt helped establish the National Foundation for Infantile Paralysis, which later became the March of Dimes. One of the aims of the Foundation was to support the search for a polio vaccine, and one of the scientists it funded was Dr. Jonas Salk, a virologist and medical researcher at the University of Pittsburgh.[3] Salk and his laboratory staff worked on developing a vaccine from 1947 to 1952. The vaccine they developed used a killed virus to trigger antibodies without creating the disease in the patient.[4]

Before being used on all children, Salk’s vaccine needed to be tested on a smaller group to see if it was safe and effective.[5] Parents volunteered their children to participate because their fear of polio far outweighed the low risks of the trial. They hoped that by participating in the trial, called Operation Polio Pioneer[6], they could help eliminate polio forever. A total of 1,800,000 children from all across America participated in the trial in 1954.[7]

Idaho’s children participated in the observed control trial. A series of three injections over six weeks’ time was given to 3,500 second-grade pupils. Seven thousand two hundred first and third graders in the same schools comprised the control group.[10] Two weeks after the final injections, blood samples were taken to check for antibodies and to compare the test results of children who had not received the vaccine.[11] The injections were given at clinics set up in elementary schools in each of the four counties. In some health districts lacking sufficient equipment, syringes had to be re-sterilized for reuse in the afternoon clinics.[12]

The clinics operated under the supervision of city and county health departments, with major support from local volunteers who did everything from taking the pupils’ medical histories to handing out lollipops. In the Idaho group, no serious after-effects from the test vaccination were reported, “the only complaint being a slight heaviness of the arm, which is normal following inoculation.”[13]

Trial Results

Following the 1954 nationwide trials, Dr. Thomas Francis, Jr., a highly respected virologist from the University of Michigan, conducted a rigorous, independent evaluation of the results. On April 12, 1955, he announced the results of his evaluation: the Salk vaccine was “safe, potent, and effective.”[14] Speaking before a crowd of 500 scientists, physicians, and reporters at the University of Michigan, Francis stated the Salk vaccine was up to 80-90% effective in preventing paralytic polio. Further, his evaluation of data showed that reactions to the vaccine were negligible. The nation celebrated. Newspaper headlines in large print read, “Salk’s Vaccine Works!” and “Polio Routed!”[15]

Nancy Shiozawa, June 20, 2021

[1] Dave Roos, “How a New Polio Vaccine Faced Shortages and Setbacks,” History.com, updated December 3, 2020, https://www.history.com/news/salk-polio-vaccine-shortages-problems.

[2] David Oshinsky, “Miracle Workers,” American Heritage 59, no. 4 (Winter 2010): 87.

[3] Oshinsky, “Miracle Workers,” 87.

[4] Karen L. Wellner, “Polio and Historical Inquiry,” OAH Magazine of History, September 2005, 55.

[5] “1955 Polio Vaccine Trial Announcement,” The University of Michigan Information and News Service, April 12, 1955, sph.umich.edu/polio.

[6] Ken Spiekerman, “Youngsters Get Second Shots in Polio Test,” Idaho Statesman, May 19, 1954.

[7] University of Michigan, “1955 Polio Vaccine.”

[8] “Four-County Polio Vaccine Test Planned,” Idaho Statesman, March 4, 1954.

[9] Marcia Meldrum, “’A Calculated Risk’: The Salk Polio Vaccine Field Trials of 1954,” British Medical Journal 317, no. 7167 (October 31, 1998): 1233-1236, https://doi.org/10.1136/bmj.317.7167.1233.

[10] “Four-County,” Idaho Statesman, March 4, 1954.

[11] “Group Outlines Polio Vaccine Tests in Area,” Idaho Statesman, March 17, 1954.

[12] Spiekerman, “Youngsters,” May 19, 1954.

[13] Spiekerman, “Youngsters,” May 19, 1954.

[14] Oshinsky, “Miracle Workers,” 87.

[15] University of Michigan, “1955 Polio Vaccine.”