For the first half of the twentieth century, American parents dreaded the arrival of summer. Warm weather brought polio, and polio brought paralysis. Poliomyelitis, a virus that attacks the nerve cells controlling the muscles, could turn a healthy child into a cripple in days, or lock the body so completely that the victim could no longer breathe and had to be sealed inside a coffin-like tank called an iron lung. Nobody understood exactly how it spread. Swimming pools closed, cinemas emptied, children were kept indoors, and each year the epidemics seemed to grow worse, peaking in the early 1950s with tens of thousands of American cases annually.
Polio's most famous victim gave the fight against it enormous momentum. Franklin Delano Roosevelt had been struck down in 1921, before he became president, and lost the use of his legs. He founded what became the National Foundation for Infantile Paralysis and, through it, the March of Dimes — a campaign that asked ordinary Americans to mail dimes to the White House. The coins arrived by the millions, and that public money bankrolled the search for a vaccine.
The killed-virus gamble
At the University of Pittsburgh, a young researcher named Jonas Salk pursued a strategy many virologists distrusted. The conventional wisdom held that only a live, weakened virus could train the immune system properly. Salk bet instead on a killed-virus vaccine: grow the poliovirus, then inactivate it with formaldehyde so it could no longer cause disease while still teaching the body to recognise and resist it. It was safer in principle — a dead virus cannot mutate back to virulence — but it had to be done with absolute precision, because a single incompletely killed batch could paralyse the very children it was meant to protect.
To find out whether it worked, the March of Dimes mounted one of the largest medical experiments in history. In 1954, some 1.8 million American schoolchildren took part, the youngest of them nicknamed the "Polio Pioneers." Hundreds of thousands received the vaccine, others a placebo, and others simply served as observed controls, in a carefully designed trial run by Salk's former mentor, Thomas Francis Junior, at the University of Michigan. Children lined up in school gymnasiums to roll up their sleeves; some wore buttons proclaiming their status as pioneers, and parents signed consent forms not knowing whether their child would receive the real vaccine or a dummy injection. It was an act of collective trust on a scale rarely seen before or since, millions of families volunteering their own children to settle a scientific question.
The bells of 12 April 1955
On 12 April 1955 — chosen because it was the tenth anniversary of Roosevelt's death — Francis stepped up to announce the results at Ann Arbor before a crowd of reporters. The vaccine was "safe, effective and potent." The words flashed around the country within minutes. Department stores stopped to broadcast the news; people wept in the streets; church bells rang and factory sirens sounded. It was treated less like a scientific finding than like the end of a war.
Salk became an instant national hero, his face on the cover of every magazine. In a live television interview, the broadcaster Edward R. Murrow asked him who owned the patent on the vaccine. Salk's reply became legendary: "Well, the people, I would say. There is no patent. Could you patent the sun?" Whether or not a patent could realistically have been obtained, the sentiment defined him — a scientist who saw the vaccine as a gift to humanity rather than a fortune to be made.
The triumph was nearly undone within weeks. A California manufacturer, Cutter Laboratories, released batches in which the virus had not been fully inactivated, causing an outbreak that paralysed and killed some children — the Cutter Incident, a disaster that led to far stricter federal oversight of vaccine production. But the programme survived, manufacturing was tightened, and polio cases in the United States plummeted.
A few years later a rival, Albert Sabin, introduced an oral vaccine using a live weakened virus, dripped onto a sugar cube. Cheaper and easier to give, it became the mainstay of the global eradication effort, though the two men remained bitter competitors to the end. Between them, Salk's needle and Sabin's sugar cube pushed a disease that once terrorised the world to the brink of extinction. Polio now survives endemically in only a tiny corner of the globe, and the summers of dread are a memory that most people alive have never had to share.
Quiz nuggets
- Jonas Salk developed a killed (inactivated) polio vaccine, given by injection, at the University of Pittsburgh.
- The 1954 field trial involved about 1.8 million American children, the youngest called "Polio Pioneers."
- Results were announced on 12 April 1955 by Thomas Francis Jr. at the University of Michigan, prompting church bells across the country.
- Asked who owned the patent, Salk replied, "Could you patent the sun?"
- Albert Sabin later developed a rival oral vaccine using a live weakened virus on a sugar cube; the March of Dimes, backed by FDR, funded the research.