Jonas Salk developed the first successful polio vaccine—and tested it on himself

A major US-designed polio vaccine was first tested in the Soviet Union

Albert Sabin's live attenuated virus vaccine—requiring two drops in the mouth—didn't garner political support in the US, so it was tested in the Soviet Union in the late 1950s.

'Our greatest responsibility is to be good ancestors.'

- Polio vaccine developer Jonas Salk (1914–1995)

Inactivated polio virus vaccine is the only one offered in the US—it contains no live virus

Inactivated polio virus vaccines cannot cause illness because the virus isn't alive. It's been the only polio inoculation offered in the United States since 2000 and provides almost complete protection

Live virus vaccines predated polio—that's how we vaccinate against smallpox

Since 1796, smallpox vaccines have used a live poxvirus related to smallpox. Yellow fever vaccines have used a live weakened form of the virus responsible for yellow fever since 1937.

View this timeline of polio milestones and vaccine development

Polio has a long history in art and medicine, dating back centuries. It includes a representation of an apparent polio survivor with a shriveled leg in ancient Egyptian art. See milestones in the history of polio in this timeline.

Improved 19th-century sanitation meant kids encountered polio later, with worse results

Almost all children likely used to contract poliovirus, but scientists suggest that when infants encountered it very early in life—due to poorer conditions and hygiene—they still had some maternal protection from pregnancy or through breastmilk, so the symptoms were more flu-like.

Edward Jenner, the father of vaccinations

The British physician was the first to attempt to inoculate someone from smallpox using its milder cousin, cowpox. His innovations and documentations would prove crucial to the deployment of widespread vaccinations.

Wastewater testing has detected genetic evidence of polio, triggering vaccine boosters

Sampling of wastewater in London in 2022 detected fragments of polio virus, suggesting a vaccine-derived version of polio may be circulating. No one became ill, but the finding did trigger calls for a renewed booster inoculation campaign.

The iron lung—a simple mechanical ventilator—was first used to treat polio

These breathing devices, developed in the late 1920s at Harvard, were used to treat polio patients with breathing difficulties. Watch this video describing how these negative pressure devices work.

A 1954 outbreak at a Boston boarding school allowed scientists to isolate the measles virus

While measles was described as early as the 9th century, humanity lacked the medical technology to fight the disease until the mid-20th century. Vaccine development from the Boston outbreak in the 1960s and 1970s led to one of the most effective inoculation campaigns in history.

Humans are the only known reservoir of poliovirus

The virus has not been found in any other species, which makes humans the only known reservoir for polio. In laboratory settings, nonhuman primates have also been infected with the virus, but there's no evidence that they contract the virus in nature.

This scientist treated her own cancer

Virologist Beata Halassy treated her own breast cancer by injecting the tumor with lab-grown viruses. Though this self-treatment worked, it has not been approved for widespread use. Read to learn more about her fascinating experience, and how it has led to conversations about safety and ethics.

Two Lyme disease vaccines were in development in 2026

As of early 2026, there was no vaccine for Lyme disease available. One candidate vaccine, VLA15, was in later-stage clinical trials. Another designed to provide seasonal protection was licensed to a pharmaceutical company in 2025, and was planned for human clinical trials.

Leonard Thompson was the first human to receive an insulin injection for diabetes

In January 1922, the 14-year-old was the first person to receive an insulin injection to treat diabetes, just months after insulin was isolated in dogs and used to treat their induced diabetes. Thompson had an allergic response to an apparent impurity in the injection, but his second dose, 12 days later, was a success.

In 1933, the influenza virus was first identified through “ferret flu” experiments

In 1933, British researchers dripped filtered nasal fluids from a sick colleague into ferrets, which quickly developed “ferret flu.” This experiment proved influenza was viral, not bacterial, and established the basis for modern flu vaccines.

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

Robert Koch won the Nobel for his tuberculosis work, but he also pioneered cholera research

Koch was one of the first scientists to isolate the bacterium that causes cholera while investigating an outbreak in Egypt in 1883. He went on to advise about rules to control cholera outbreaks, which formed the basis of the disease control approaches and water hygiene techniques still used today.

An Ebola vaccine was developed during the 2018 west African Ebola outbreak, but the 2026 Ebola outbreak is with a different species of the virus, not the one that the vaccine is approved to treat.

A fake vaccine campaign was used to locate Osama bin Laden, fueling vaccine distrust

As part of the intelligence operation to find bin Laden in Pakistan, the US Central Intelligence Agency recruited a Pakistani doctor who ran a fake hepatitis B vaccine campaign and obtained DNA samples from bin Laden. News of this fake campaign fueled further distrust of healthcare workers, attacks on them, and stymied efforts to vaccinate against polio in the region.

The first computer virus was created by a USC doctoral candidate in 1983

A year after creating malware in a controlled experiment that multiplied until it took over all of a computer's memory, Fred Cohen went public with his research and its risks. He called the self-replicating software a "computer virus," a term Cohen's advisor, Leonard Adleman, coined to describe its infectious behavior. (Some readers may experience a paywall.)

How mRNA vaccines work

mRNA COVID-19 vaccines were developed faster than any vaccine ever made. Even more enticing, the underlying technology may unlock preventive treatments for a wide-range of diseases.

Listen to how the 1902 'poison squad' experiments changed food safety in America

As part of government research, a group of young men were paid to eat standard American food—replete with food additives like borax and formaldehyde—which revealed the dangers of unregulated food. The work was led by the first FDA commissioner, Harvey Wiley, who helped end the "century of the great stomachache."

Magic Johnson's announcing he had HIV changed public perception of the disease

When Lakers superstar Magic Johnson announced he had HIV in 1991, the disease was highly misunderstood. Commissioner David Stern had behind-the-scenes conversations with Johnson about publicly handling his eventual announcement, leading to the start of the condition's destigmatization.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

Dr. William Gorgas eradicated yellow fever in Panama, crucial to canal construction

The disease was one of the factors hampering the French effort to build the canal. Gorgas' experience elsewhere in the Caribbean had taught him that good drainage and quaranting patients were essential, and he would eventually apply mosquito prevention tactics on a mass scale.

Watch how Sanger sequencing kickstarted the first generation of DNA sequencing

Sanger sequencing is a foundational DNA sequencing technology developed in 1977. The Nobel Prize-winning discovery uses fluorescent dyes at the end of DNA chains, which are sorted by length through electrophoresis, to determine the order of nucleotide bases.

The first practical silicon solar cell was developed at Bell Labs

In 1953, scientists at Bell Labs attempted to develop a power source for phone systems in remote locations, as the dry battery cells lacked the necessary longevity. They experimented with solar power, but the selenium solar cells of the time were too inefficient, eventually leading to the usage of silicon.

Read a history of how oral rehydration solution was created

Experiments dating back to the 1940s eventually led to the creation and standardization of a mixture of sugar, salt, and clean water that is now widely used globally.

Elk Cloner, the first computer virus to spread in public, was written as a practical joke by Richard Skrenta, a Pittsburgh high school student.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

How the most famous Ebola book, The Hot Zone, which sold 3.5 million copies and was translated into 30 languages, got aspects of the disease so wrong.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

The animatronic shark from Steven Spielberg's 'Jaws,' the first modern blockbuster, was a complex underwater apparatus called 'Bruce.'

Jimmy Carter signed a 1978 bill that legalized home brewing, a move credited with kick-starting the craft beer industry.

This poison ivy knowledge quiz—accompanied by photos of the plant's varied forms—may help you identify this common rash-inducing growth.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

Brian Wilson wrote the Beach Boys' 'Don't Worry Baby' for the Ronettes, but the legendary girl group rejected it.

In 2009, the nation was gripped by the story of a missing young boy who was believed to be floating over Colorado in a homemade balloon, until it was revealed that he was at home the whole time.

Watch a 1934 short film starring jazz legend Cab Calloway, a major figure in the Harlem Renaissance's music scene

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Abraham Lincoln was almost assassinated weeks before his inauguration as he traveled from Illinois to DC through Baltimore in 1861; it took two independent claims for Lincoln to be convinced the threat was real

An initial public offering or 'IPO' is the process of a private company becoming public by putting shares of the company on the stock market for purchase.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.