A girl with polio meets one of the first children to get a polio vaccine.
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Of the more than 200 Americans infected by the measles outbreak in Texas and beyond, nearly all were unvaccinated — including a 6-year-old child who died — or had an unknown immunization status. While a measles epidemic affecting hundreds of people across state lines is hard to imagine in 2025, the vaccine fears that help fuel these outbreaks are as old as vaccination itself. Even when some of the worst diseases known to humankind threaten lives, there have always been those who fear the vaccine more than the disease.
In the early 1800s, some people rejected the smallpox vaccine because they didn’t trust the doctors and scientists promoting them, or because they saw vaccines as an affront to God’s will, or because they worried about dangers they’d heard or witnessed. That the early version of the vaccine occasionally spread infection only heightened those fears.
So governments increasingly made vaccination mandatory. Over a century ago, refusers could face quarantine, fines or even jail time. Vaccination objections grew. People argued that mandatory vaccination undermined individual liberty, or that the diseases the vaccines prevented weren’t that serious.
A boy wearing a bandage typical for mumps patients, with his dog wearing a matching bandage.
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A boy taking part in the clinical trials for the live-virus measles vaccine.
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Those ideas persist today. Popular influencers are calling diseases like measles and mumps “no big deal.”
The modern-day childhood vaccine schedule has allowed children to grow into healthy adults — something all parents hoped for in the centuries when diseases emptied towns, destroyed economies, ravaged battalions, overwhelmed hospitals and vexed nurses and doctors. For people who’ve never seen them, the worst manifestations of some of these preventable diseases are almost unimaginable. It’s worth remembering their toll.
To understand how common these diseases were before vaccines, we reviewed historical surveys asking parents if their children had contracted them. The estimates are rough, but underscore just how much these diseases have faded from public memory.
Smallpox
Vaccine created in 1798
Smallpox caused fever, headache, nausea, racking body aches and a rash of excoriating, pus-filled blisters. Sleepless victims suffered night terrors and delusions. In the worst historical cases, the pustules spread so densely that they covered the surface of the body, crusted over the eyes, and coursed over the mucous membranes until internal hemorrhaging led to certain death. A smallpox outbreak could kill up to 30 percent of people infected. Survivors were often left pock-marked and blind.
The smallpox vaccine, originally developed with virus from a milder animal disease, cowpox, led to smallpox’s global eradication in 1980 — the ultimate vaccination success story.
Diphtheria
Vaccine created in 1914
At its height over a century ago, diphtheria was often mistaken for a sore throat. Bad cases were identifiable only by the sweet-smelling, putrid-colored membrane of bacteria and decaying cells covering the patient’s tonsils and throat. Diphtheria bacteria churn out a toxin that can cause paralysis, but in 19th-century epidemics, sick children often died of suffocation first. In the deadliest outbreaks, 30 percent to 50 percent of infected children perished.
Diphtheria was an unpredictable roulette of mild and deadly outbreaks until a vaccine was developed that could finally protect children from the disease’s terrors.
Pertussis
Vaccine created in 1914
Formally known as pertussis, whooping cough often begins like a minor cough or cold. Weeks later, the cough is still there, unrelenting. Before antibiotics or vaccines, the patient’s cough would grow violent and uncontrollable, terminating in its namesake “whoop” sound. In young children, the whoop would often lead to vomiting. In a severe case lasting weeks, a child might whoop and vomit several times an hour. Babies couldn’t forcefully take in enough air to whoop, and the lack of oxygen meant they’d turn blue.
The first pertussis vaccines were manufactured in 1914, and a modern version was developed in the 1930s. A combined diphtheria, pertussis and tetanus vaccine was created and given to many American children by the end of the 1940s.
Polio
Vaccine created in 1955
The first U.S. polio epidemic was documented in the 1890s and further outbreaks followed. It peaked as other infectious diseases, like smallpox and measles, were fading from view and concern. Most polio infections are minor, with some causing a fever and sore throat. In less than 1 percent of infections, the virus attacks nerve cells in the brain and spinal cord that control movement. Some patients are partly paralyzed. Others lose the ability to swallow properly, walk or breathe. The worst cases were fatal.
The first polio vaccine was approved for use in 1955, and the disease was eliminated from the Americas by 1994. Today, polio regularly circulates in just two countries, but outbreaks crop up where war and deprivation allow it to take root.
Measles
Vaccine created in 1961
When the first European colonists brought measles to the Americas, it was so infectious that it spared almost no one. It caused a vivid red rash and fevers that spiked so high and for so long that the sick searched desperately for relief from measles’ fiery heat. In populations that had never seen the virus before, measles could kill up to a quarter of people. In previously exposed populations, it could still kill 20 percent of children.
In the mid-20th-century United States, thanks to overall improvements in nutrition, hygiene and medical care, measles death rates remained low. But the virus can have alarming complications, including pneumonia, brain swelling, rare but terrifying brain inflammation and an altered immune system that lasts long after the disease itself resolves.
The scientific developments behind the first polio vaccine helped make the first measles vaccines possible in the 1960s. With the vaccine’s growing use, cases began to tumble.
Mumps
Vaccine created in 1967
A military doctor caring for 18th-century British infantrymen was troubled by what happened when his troops caught the “gangrenous” sore throat that was spreading across Europe. In his patients, jaws and testicles swelled to an alarming size. At least one of his men died; others recovered with their testicles permanently atrophied. After two more centuries, doctors eventually agreed mumps could similarly affect women’s breasts, ovaries and other reproductive organs. By the mid-20th century, scientific focus shifted to children, whose mumps led to huge and painful swelling of the salivary glands, which could spread to the brain and leave a child deaf.
The measles vaccine inspired one for mumps, and by the end of the 1970s it was recommended for all American children, with cases diminishing over the next decade.
Rubella
Vaccine created in 1969
Children used to catch rubella without much fanfare, developing little more than cold symptoms. But when contagious children passed the disease to pregnant women, the fetus was at grave risk. The virus, which typically invades the airways, can travel to the placenta and disrupt the fetus’s rapidly dividing cells. Before children were given the vaccine, rubella infections resulted in many miscarriages and stillbirths. Many children were born with birth defects such as cataracts, hearing loss and severe heart and bone deficiencies. In very rare cases, children developed neurological deficits, leaving them with chronic seizures and physical and intellectual disabilities.
A 1964 epidemic affected 20,000 infants and prompted research for a vaccine that was ultimately folded into the combined M.M.R. vaccine in 1971. Today, the United States sees only a few cases a year.
How we came up with these estimates
Data on the number of cases for these diseases from the pre-vaccine era is hard to come by, and even the case counts are extremely unreliable. Many estimates suggest that perhaps only 10 percent of cases for most of these diseases were reported. As a result, we turned to historical surveys.
For mumps, rubella, diphtheria, measles, and whooping cough we used two surveys from before 1930, one that surveyed 14 communities and another that surveyed three.
For smallpox, we relied on secondary references to the prevalence during the 18th century. For polio, we made a rough calculation of the probability that a child would contract polio over his childhood based on average annual case rates acquired from Project Tycho.
All of the rates given are for approximately how many kids got each disease at some point during their childhoods.
