"One of the Greatest Events in the History of Medicine": The Defeat of Polio
March 30, 2020
A major part of modern human history has been the fight to defeat disease, from tuberculosis to measles to waterborne illnesses like cholera. One of humankind’s greatest triumphs in that never-ending battle came only some 65 years ago, when Jonas E. Salk developed a vaccine against polio. Within six years, incidences of the deadly disease were down by 90 percent in the United States; within twenty-five it was eliminated from the country. Today, it has been mostly extinguished across the globe.
But, in the middle of the last century, poliomyelitis, also known as infantile paralysis, was a terrifying scourge. While the disease had been documented as far back as the time of ancient Egypt, it evolved into an ever-more pressing problem around the 1920s. Over the following decades, epidemics continually devastated America, hitting especially hard in the late 1940s and early 1950s.
Each summer, polio would wrack the population, especially children, sickening thousands, paralyzing a large portion, and killing many. In the five years leading up to 1955, there were an average of 25,000 cases a year in the United States. In 1952, the worst year on record, more than 3,000 of 58,000 cases died; in Chicago alone, 82 of 1,203 reported cases died.
Polio first manifested in flu-like symptoms, then led to paralysis of the limbs. Survivors described waking up from sleep unable to move. Severe cases led to treatment in an artificial respirator called an iron lung. A patient’s whole body from the neck down was enclosed in the forbidding-looking contraption, which created a vacuum that drew the lungs up and down, helping people lacking muscle power to breathe.
While the disease primarily struck children, no one was completely safe: Franklin Delano Roosevelt, perhaps polio’s most famous victim, contracted it when he was 39, and was left partially paralyzed. Senate Majority Leader Mitch McConnell had polio as a two-year-old and was unable to walk until he was five; Chicago’s one-time cardinal Francis George had permanent damage to his legs from the disease.
To combat polio, in 1938 FDR created the National Foundation for Infantile Paralysis, later called the March of Dimes due to its fundraising request to send in a dime. Scientists sought to develop a vaccine for the disease, most working with a live version of the virus. But the young Jonas Salk, a garment worker’s son who had studied the influenza virus and worked on commercial flu vaccines during the war with the respected Dr. Thomas Francis of the University of Michigan, went against conventional wisdom and devoted his attention to a killed virus vaccine.
“I guess I felt the unreasonableness of life in so many ways,” he later told the New Yorker about why he went into research. “Research was one way to get at reasonableness and logic.”
He conducted a small trial in 1952 near Pittsburgh with a group that he told the New Yorker “helped us look into the future.” Another limited trial followed in 1953, then, in 1954, the March of Dimes pushed for a large-scale field trial—the largest experiment of its kind in history. More than a million people took part, with 440,000 inoculated with Salk’s vaccine and the others with a placebo. Illinois’s DuPage County, outside Chicago, was involved, with 8,000 children given the vaccine at their schools, their teachers lauding them for being “polio pioneers.”
After a year of observation by an independent team led by Salk’s old mentor Dr. Francis, a press conference was held to announce the results of the trial. “Nobody could recall a medical press conference quite like this one,” wrote the New York Times in a review of a biography of Salk. “[F]amilies huddled around radios, as if listening to the World Series or a championship fight. Crowds watched on television sets lining department store windows.”
On April 12, 1955—the tenth anniversary of FDR’s death—Francis announced that the vaccine was 80-90 percent effective. The chairman of the American Medical Association called it “one of the greatest events in the history of medicine.” President Eisenhower called Salk a “benefactor of mankind.” According to the New York Times obituary for Salk, who died in 1995, “an opinion poll ranked him roughly between Churchill and Gandhi as a revered figure of modern history.” In 1999, Salk appeared in an illustration on the cover of Time magazine’s “100 Greatest Minds of the 20th Century” issue alongside Freud and Einstein.
The success of the vaccine was astounding. Widespread vaccination was launched in the United States in 1955. As Salk himself boasted to the New Yorker, “In the late nineteen-forties and early nineteen-fifties there were close to three thousand cases of polio per week during several consecutive weeks in most of those years and in 1960 there were just over three thousand cases the entire year.” The last reported case of polio in the United States was in 1979. Globally, cases were reduced from around 350,000 in 1988 to 1,000 in 2003, and the disease has been all but wiped out.
The live virus vaccine developed by Salk’s rival Albert Sabin—first licensed in 1961— eventually overtook Salk’s killed virus vaccine in popularity since it was cheaper to produce and easier to administer (it is an oral vaccine). But Sabin’s vaccine could occasionally cause someone to contract the disease, and around the turn of the millennium the United States went back to a killed virus vaccine.
In 1963, the Salk Institute for Biological Studies opened outside San Diego with financial support from the March of Dimes. It is now a revered institution that has produced numerous Nobel laureates—a recognition that eluded Salk. Only in his late 30s when he developed the polio vaccine, Salk struggled to find another success to match his first.
The development of the polio vaccine presaged later victories in creating effective preventatives against other infectious diseases such as influenza, measles, and mumps, unfounded contemporary skepticism against vaccines notwithstanding. (2019 saw one of the worst measles outbreaks in the United States in decades, with the majority of cases among people who were not vaccinated.)
In 1981, WTTW’s John Callaway spoke with Salk about his career and the development of the polio vaccine. Discussing the public response to a successful vaccine, Salk said, “it is always the lifting of fear that they appreciate so.”
Update: The April 1 Google Doodle features Dame Jean Macnamara, an Australian doctor whose birthday is April 1. Macnamara was crucial in studying the polio virus and discovering that there were multiple strains of the virus in 1931, a discovery that helped lead to the Salk vaccine two decades later.