Measles was declared eliminated in the US in 2000

The measles vaccine has saved an estimated 94 million lives since its introduction

Measles killed an estimated 2.6 million people globally in 1980, after the development of a vaccine but before its widespread dissemination. By 2014, that figure had dropped to an estimated 73,000.

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.

Current US measles outbreak data from the CDC

This data portal from the Centers for Disease Control and Prevention tracks current cases, hospitalizations, and deaths from measles. A 2025 outbreak in Texas and New Mexico drove US cases to their highest levels since the early 1990s.

Measles infection can cause long-term immune system “amnesia”

The measles virus attacks the body's immune system, including preying on T and B cells in the lymphatic system. These cells hold memories of past infections, which can be degraded as the virus destroys them. This leaves patients susceptible to other infections for a year or longer.

Measles is one of the most contagious preventable diseases

The virus’s ability to persist in the air for up to two hours means an infected person could enter a room, leave, and two hours later infect someone else entering the room. Its location in the body’s upper respiratory tract also makes it easy for viral particles to be sneezed or coughed into the air.

A heatmap showing the drop in infectious diseases post-vaccine deployment

The number of infected people, measured over 70-some years and across all 50 states and the District of Columbia, declined significantly after vaccines were introduced.

Measles symptoms range from fever to pneumonia and encephalitis

While less common, most measles-related deaths come from secondary conditions such as pneumonia (one to six cases per 100 patients) and encephalitis (one case per 1,000 patients). Blindness, which is rare, may arise from corneal ulceration.

What is the measles, mumps, and rubella vaccine?

Federal guidance currently recommends a two-shot schedule of the MMR vaccine for children in most cases, once at 12 to 15 months and once at 4 to 6 years. (A September 2025 update only called for the elimination of a combined vaccine that included protection against varicella, the MMRV shot.)

Only one strain of wild poliovirus continues to infect humans

Three strains of polio used to regularly infect humans, but two of the strains were declared eradicated in 2015 and 2019, respectively. In 2019, world health leaders estimated complete polio eradication—if achieved—would save $14B by 2050.

Vitamin A does not cure measles, but it helps reduce the symptoms

Also known as retinol, vitamin A plays a significant role in supporting the body’s immune system. The virus attacks the immune system, and studies have shown a correlation between vitamin deficiency and severity of measles symptoms. Supplemental vitamin A doses are now a part of recommended treatment for pediatric patients.

The CDC’s “Pink Book” chapter on measles

The agency’s “Pink Book” is meant to be a comprehensive guide on various diseases and their treatments. This chapter on measles reviews how it works and common symptoms, and provides information on the MMR and MMRV vaccines.

Penicillin ended scarlet fever’s deadly threat to children

Between 1840 and 1883, scarlet fever was among the leading causes of childhood death in the United States, with case fatality rates ranging from 15% to 30%. Today, thanks to antibiotics like penicillin, the mortality rate is below 1%.

In 2012, a virus that causes HFMD may have killed dozens of kids in Asia

More than 50 young children in Cambodia died in spring 2012 for unknown reasons, but laboratory testing of samples available from a limited number of those children came back positive for Enterovirus 71. That virus, which can cause HFMD, is known to cause severe complications among some people who contract the disease. But health officials concluded that poor baseline health and then incorrect treatment using steroids helped exacerbate their condition, helping lead to the deaths.

Herd immunity works by slowing down viral transmission until it dies out

Herd immunity refers to a population whose vaccination rates against a given virus are high enough that transmission dies out before the bug can find the next unvaccinated person to infect. Rates needed to achieve this depend on how contagious a virus is. This video gives a quick visual explanation of how it works.

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.

US cancer mortality rates have been falling for 25 years

The American Cancer Society's "Cancer Facts & Figures 2025" report provides comprehensive statistics on cancer incidence, mortality, and survival rates in the United States. Cancer rates in the US continued a long-running downward trend, driven primarily by a steep drop in lung cancers (mostly from a decrease in habitual smoking) and better preventative monitoring. This site leads to incredibly in-depth reports and slides on the current state of the fight against cancer.

Foot-and-mouth disease, which affects animals, has been eradicated in many locations

The disease, which causes fevers and painful blistering in the mouth, muzzle, snout, teats, and feet—somewhat similar to hand, foot, and mouth disease in people—is transmitted via contact with infected animals or their fluids or eating infected foods or meat. Though it primarily affects cloven-hoofed animals, it's also been known to sicken camels and even elephants.

Peanut allergies dropped by 43% after doctors reversed avoidance guidance, but questions remain

The study’s data appear to confirm the policy shift. Still, since the study did not include an examination of infant diet, researchers can’t definitively say that the guideline shift led to dietary changes and thus directly caused the decline.

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.

Iceland, the last mosquito-free country, detected them in 2025

Recently several of the mosquito species Culiseta annulata were documented in Iceland—the last country that had not yet seen them, underscoring that climate change is shifting the bugs' patterns. Mosquitoes can hide out in human structures to survive icy temperatures. The bugs are now known to live everywhere except the continent of Antarctica.

In 1865, Hawaii's king authorized forcible removal, quarantining of those with leprosy

King Kamehameha V authorized the removal of anyone with leprosy symptoms and for them to be placed in a medical facility later maintained by the Catholic Church on Moloka'i, Hawaii's fifth largest island. Patients weren't allowed to transfer to other medical facilities until 1969.

The US FDA considered mitochondrial replacement therapy during 2014 hearings

An agency committee assessed if this approach could have undesirable ripple effects across multiple generations and whether a clinical trial involving this approach would be appropriate. As of 2026, the US has continued to prohibit this procedure though it is legal in other settings including the UK and Australia.

The Montreal Protocol helped prevent significant quantities of greenhouse gas emissions

By phasing out ozone-depleting chemicals between 1990 and 2010, the Montreal Protocol prevented emissions equal to 135 gigatons of CO₂—avoiding an estimated 0.5 to 1 degrees Celsius of additional global warming by 2100.

Menopause is defined as 12 months without a period

Menopause is officially when a woman stops getting her period, meaning she has stopped ovulating and can no longer get pregnant. A woman has to go a full year without bleeding or spotting to know she has hit menopause.

The de minimis exemption was a US tariff loophole

Until Aug. 29, 2025, US consumers could purchase up to $800 of goods per day, directly from an overseas company without incurring any tariffs on the products.

US honeybee colony loss remains a concern, despite rebounding from the mid-2000s CCD

In the winter of 2006-07, worker honeybees began mysteriously disappearing from hives—a phenomenon known as colony collapse disorder—triggering the loss of as many as 90% of hives. The lack of dead bees found near hives and the declining prevalence of CCD since then have made finding a single cause challenging.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak each year.

Tattoos remain visible on your skin thanks to immune cells called macrophages

View the ten deadliest tornadoes in US history.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

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.

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.

Fireworks-related ER visits are on the rise—in 2024, they increased by 52% as compared to the prior year.

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.

A century of Billboard issues documenting the evolution of popular music.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

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

The story of Dollree Mapp, whose legal challenge over her 1957 conviction for possessing "obscene material" led to a major strengthening of the Fourth Amendment

The United States has had a tumultuous relationship with Cuba since its 1959 revolution, highlighted by a nuclear crisis and a decades-long trade embargo.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

Watch contemporary footage covering the US-backed Shah of Iran fleeing the country in the face of the 1979 Iranian Revolution

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

Explore an interactive map of battles from the American Revolution, along with detailed summaries of each engagement

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

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 Russia-Ukraine conflict is the largest ground war in Europe since World War II in terms of casualties, forces mobilized, and displacement of civilians.