View this timeline of polio milestones and vaccine development

See the polio cases that occur worldwide each year by region

Worldwide, the number of cases of polio reported each year from 1980 to 2024 has declined. This graphic depicts regional trends and declines by year.

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.

Poliomyelitis is derived from Greek

Polio, formally called poliomyelitis, comes from the Greek words for gray (polios) and marrow (myelos)—a reference to the spinal cord tissue that, when infected by the virus, causes paralysis.

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.

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

The American medical researcher developed the inactivated virus vaccine from 1952 to 1955 and proved that it could prevent disease. He tested the virus on himself and his family in 1954 and then carried out formal clinical trials on more than 1.3 million children.

Oral polio vaccines cause approximately 250 to 500 polio cases per year globally

Live, weakened polioviruses in the oral vaccine can very rarely mutate into a disease-causing form and lead to vaccine-associated paralytic poliomyelitis. This oral vaccine is not available in the United States.

Post-polio syndrome occurs decades after infection but isn't contagious

Affecting adults who contracted polio as children, this disorder can occur 15 to 40 years later, leading to slow, irreversible muscle weakening. Some research estimates that between 25% and 40% of polio survivors go on to develop this condition.

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.

See the evolution of Ebola vaccine and treatment development.

Human records of influenza stretch back more than two millennia

Accounts of flu-like illness appear as early as 412 BCE, when Hippocrates described a sudden wave of cough and fever. Centuries of recurring outbreaks culminated in the first clearly documented pandemic in 1580, spreading from Asia into Europe and Africa.

After FDR was paralyzed by polio in 1921, Eleanor Roosevelt became active in politics and supported his political ambitions

FDR contracted polio at age 39 and permanently lost the use of his legs. Eleanor Roosevelt persuaded him to stay in politics, then took on the task of maintaining his public profile—attending events, building relationships, and serving as his "eyes, ears, and legs" across the country.

The board game Candyland was invented for children quarantined in polio wards.

Silicon Valley’s history in technology can be traced back to the late 1800s

From its developments in radio, defense technology, and personal computing, Silicon Valley has been associated with innovating tech for more than a century. This animated timeline of Silicon Valley’s history helps visualize its evolution.

A history of vaccine rollouts

History tells us the public will tolerate risk of harm from a vaccine if their fear of the disease exceeds their fear of the vaccine.

Key milestones in the history of the World Health Organization

The World Health Organization, a UN agency founded in 1948, was first proposed at the 1945 UN Conference to coordinate global health efforts. This interactive timeline marks the WHO’s 75th anniversary with major public health milestones.

Timeline of cancer research milestones

While cancer remains incurable, there's been so much progress in its treatment over the last two decades. Nature provides an abridged history of milestones and major triumphs in cancer research and treatment. Start in the year 2000, and see how much has changed in the first quarter of the new millennium

Nail art can be traced back to 5,000 BCE

Archaeologists discovered Egyptian mummies with nail art and henna-tinted fingertips. The trend would continue informally for centuries until Revlon introduced modern nail polish in 1932.

A gallery of medical illustrations from NIH

The National Institutes of Health provides educational materials for broad use. The institute hosts a Flickr account with many different image galleries, including this one (with over 70 images to date) that illustrate and annotate curious phenomena, from the life cycles of a malaria parasite to the comparison of male and female bladders. Explore the gallery here.

Medieval hospitals existed centuries before modern medicine

Long before modern healthcare, medieval Europe established hospitals that served multiple roles, including religious, social, and medical purposes. This podcast explores how institutions like Siena’s Ospedale di Santa Maria della Scala supported urban and rural communities for centuries.

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

The history of the Met

From a single sarcophagus to a collection of more than a million artifacts that span nearly the entirety of human civilization, the Met and its importance have grown significantly over the last 150 years. This history of the museum hits all the highlights, including important acquisitions, new wings and galleries, and the importance of the buildings that hold and display all of the incredible artwork.

Why pickles became a thing

Pickles began in Mesopotamia around 2400 BCE as a way to preserve vegetables amid heat (and spoilage). They spread through Egypt, Greece, and Rome, where Julius Caesar reportedly fed pickles to his soldiers, and brining was treated as a culinary art. The technique is broadly useful, as salt and water can extend the shelf life and deepen flavor for almost anything.

The evolution of the Olympics from ancient Greece to the modern world

The Olympic Games have evolved from a sacred footrace in 776 BCE honoring Zeus to a global celebration of athletic excellence and unity. Ancient Greek city-states set aside their conflicts under a sacred truce for events like wrestling and chariot racing. Though the Games ended in 393 CE, Pierre de Coubertin revived them in 1896, adding modern elements like the torch relay and the inclusion of women. Watch 1440's breakdown of the historic event here.

Pilates was invented by an acrobatic WWI prisoner of war

As the Great War raged on, and as months gave way to years, the imprisoned Joseph Pilates explored a question that he had pondered since childhood: Could he reimagine the capabilities of the human body through an anatomically based method of training, taking inspiration from scientific treatises, the carefree movement of children, and the dexterous ease of cats? Read this article to learn about the birth and legacy of Pilates.

The history of malware includes computer viruses, worms, trojans, and ransomware

Some of the earliest significant pieces of malware—the Creeper worm and the Elk Cloner virus—displayed silly messages to users without causing major harm. As computer science has advanced, malware has become more easily spread, incorporated social engineering to manipulate users, targeted infrastructure systems, and been used by governments for virtual espionage.

'Potter Puppet Pals' was one of the internet’s first viral videos

Created by animator Neil Cicierega in the early 2000s, Potter Puppet Pals featured felt puppets parodying the Harry Potter characters. Its 2007 video “The Mysterious Ticking Noise” became an early YouTube sensation, amassing more than 200 million views.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

Graffiti dates back to at least ancient Pompeii, where citizens scrawled messages to one another on public walls

See the most iconic photos from four decades of LIFE magazine

See images of medical cases of firework injuries shared on this 'Instagram for doctors.' (Warning: Graphic content)

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity, where it was purposefully grown in the English royal gardens at Kew, the Faculty of Medicine in Paris, and a few other locations.

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

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

See these 16 pieces of art evoking phobias of snakes, flying, spiders, and more. 

This real-time tracking of the hantavirus cruise ship outbreak in May 2026 offers a unique glimpse into the global reach of the outbreak and whether the virus sickened passengers and their communities around the world.

Walt Disney's early film 'Alice's Wonderland' was a groundbreaking innovation in the silent film era

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

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.

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

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

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

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 US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

In 2025, four executives from large tech companies were given positions in the US Army Reserves—including Palantir Chief Technology Officer Shyam Sankar, which reinforced Palantir's ties with the US military and its role as a leading defense partner.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

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.

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.

The term 'algorithm' originated from the Latinized name of al-Khwārizmī, a 9th-century mathematician whose works introduced Arabic numerals and the decimal-based numeral system to Europe and whose treatise 'Al-Jabr' gave algebra its name.