Jonas Salk announces a working polio vaccine, ending decades of fear

Story: 1955 C.E.  |  Last updated: April 12, 1955

On April 12, 1955 C.E., the University of Michigan announced results that stopped a nation in its tracks: Jonas Salk’s inactivated polio vaccine was safe and effective. Church bells rang. Strangers embraced in the street. Judges adjourned courts. For millions of families who had spent every summer dreading the disease, the news felt like the end of a long siege.

Key findings

• Polio vaccine: Jonas Salk’s inactivated poliovirus vaccine, announced in 1955 C.E., was the result of years of laboratory work that used killed virus to trigger immunity without risking infection.
• Salk trial: The field trial behind the announcement was one of the largest in medical history — involving roughly 1.8 million children across the United States, known as “Polio Pioneers.”
• Global eradication: Together with Albert Sabin’s oral vaccine, introduced in 1961 C.E., the two vaccines helped cut confirmed polio cases from an estimated 350,000 per year in 1988 C.E. to just 33 in 2018 C.E., according to the World Health Organization.

Why polio terrified the world

Polio had haunted human populations for millennia, but it reached epidemic scale in the twentieth century. In the United States alone, the 1952 C.E. outbreak left nearly 58,000 people infected, more than 3,000 dead, and over 21,000 with some degree of paralysis. Most victims were children. The disease struck without warning — a child could go to bed healthy and wake unable to breathe.

Parents kept children away from public pools, movie theaters, and playgrounds each summer. The iron lung — a machine that breathed for patients whose chest muscles had failed — became one of the most recognizable and feared images of postwar America. Fear of polio was not irrational. It was everywhere.

Salk, working at the University of Pittsburgh, took a controversial approach. Many virologists of his era believed only a live, attenuated virus could produce lasting immunity. Salk disagreed. He killed the virus with formaldehyde and showed the body could still learn to fight it. His approach worked — and it was safer.

How the vaccine came together

Salk’s work built on decades of contributions from researchers across the world. John Enders, Thomas Weller, and Frederick Robbins had won the Nobel Prize in 1954 C.E. for showing that poliovirus could be grown in non-nerve tissue in a lab — a discovery that made vaccine development practical. Isabel Morgan at Johns Hopkins had demonstrated that killed-virus preparations could protect monkeys. Salk synthesized these lines of research and pushed them into human trials.

It is also worth noting that Hilary Koprowski had already demonstrated a working oral polio vaccine in 1950 C.E. — five years before Salk’s announcement — using a live attenuated virus. Koprowski’s vaccine was not approved in the United States but was used successfully in other countries. The story of polio’s defeat is not a single heroic act. It is the outcome of layered scientific work across institutions, nations, and decades.

The 1954 C.E. field trial was organized by the National Foundation for Infantile Paralysis — later known as the March of Dimes — which had raised money from ordinary Americans, many of whom sent dimes directly to President Roosevelt, himself a polio survivor. The involvement of a broad public in funding and participating in the trial was itself extraordinary.

Lasting impact

The polio vaccine reshaped what humanity believed medicine could accomplish. Before 1955 C.E., most people accepted epidemic disease as a fact of life. After the announcement, the idea that science could systematically eliminate a disease — not just treat it — became a genuine operating principle of global public health.

Albert Sabin’s oral polio vaccine, approved in 1961 C.E., extended the reach further. Easier to administer and requiring no syringes, it became the tool of choice for mass vaccination campaigns in lower-income countries. The Global Polio Eradication Initiative, launched in 1988 C.E., used both vaccines to drive the virus to the edge of extinction. Wild poliovirus type 2 was declared eradicated in 2015 C.E. Wild poliovirus type 3 followed in 2019 C.E.

The infrastructure built to deliver polio vaccines — cold chains, community health workers, village-by-village outreach — became the backbone of broader immunization programs worldwide. The lessons learned from polio campaigns directly informed the global response to other diseases, including measles, meningitis, and, decades later, COVID-19.

Salk famously declined to patent the vaccine. When asked who owned it, he said: “The people.” That decision — contested by some historians who note Salk had little legal ability to patent it regardless — nonetheless became a symbol of medicine in service of humanity rather than profit.

Blindspots and limits

The story has real shadows. In April 1955 C.E., a manufacturing error at Cutter Laboratories produced vaccine batches containing live virus, causing 40,000 cases of polio, 200 children left with paralysis, and 10 deaths — a disaster that nearly derailed the entire program. The oral vaccine, while transformative, carries a small but real risk: roughly one case of vaccine-associated paralytic poliomyelitis per 2.7 million doses. By 2017 C.E., more cases of circulating vaccine-derived poliovirus were recorded than wild poliovirus, a sign that the final mile of eradication remains genuinely hard.

Polio has not been eradicated. As of 2024 C.E., wild poliovirus type 1 still circulates in Afghanistan and Pakistan. Conflict, vaccine hesitancy, and logistical barriers in remote regions continue to slow the last push. The science succeeded. The social and political conditions for total eradication remain unfinished work.

Read more

For more on this story, see: Wikipedia — Polio vaccine: Society and culture

For more from Good News for Humankind, see:

• Alzheimer’s risk cut in half by drug in landmark prevention trial
• U.K. cancer death rates down to their lowest level on record
• The Good News for Humankind archive on global health

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