Vaccination and the Diseases That Vanished — A Century of Vaccines in One Chart

The heart of this story is a comparison, and it is a stark one. For each vaccine-preventable disease, we can line up the estimated number of cases in a typical year before the vaccine existed against the number of cases reported in recent years. The table below draws on historical morbidity estimates compiled by the immunization education nonprofit Immunize.org, which pairs pre-vaccine baselines with recent case counts from national surveillance data.

Read down that final column and the pattern is almost monotonous in its consistency. Not a 30% dip here or a 50% improvement there, but reduction after reduction of more than 90%, frequently more than 99%, and in a couple of cases a clean 100%. A peer-reviewed analysis of these trends, published in the medical journal JAMA by researchers Sandra Roush and Trudy Murphy, reached the same conclusion in more formal terms: for the diseases with vaccines recommended before 1980, the United States achieved at least a 92% drop in reported cases and a 99% or greater drop in deaths, as documented in their historical comparison of morbidity and mortality.

What makes the chart so persuasive is not any single row. It is the fact that every row tells the same story. One disease vanishing might be luck, or better plumbing, or a quiet stroke of good fortune. Eleven diseases collapsing in the same direction, each shortly after its own vaccine arrived, is a pattern — and patterns are what turn a nice-looking chart into genuine evidence.

To understand the chart, it helps to see the timeline that produced it. The modern vaccine story stretches back more than two hundred years and picks up speed dramatically in the twentieth century. Vaccine history timelines maintained by the Children's Hospital of Philadelphia lay out the key U.S. milestones, and the shape of that timeline maps neatly onto the drops in the chart.

• 1796 — Edward Jenner demonstrates that material from cowpox can protect against smallpox, producing the first scientifically tested vaccine.
• 1920s — A diphtheria toxoid is developed, taking aim at one of the era's most feared childhood killers.
• 1940s — A whole-cell pertussis vaccine appears, and the combined DTP shot arrives in 1948.
• 1955 — Jonas Salk's inactivated polio vaccine is licensed, followed by Albert Sabin's oral polio vaccine in the early 1960s.
• 1963–1971 — Vaccines for measles (1963), mumps (1967), and rubella (1969) arrive, and are combined into the single MMR shot in 1971.
• 1980s–1990s — Hib conjugate vaccines sharply cut childhood meningitis, and a varicella (chickenpox) vaccine is licensed in 1995.
• 2006 — Rotavirus and HPV vaccines join the routine schedule.

Before that timeline began, families had little to fall back on beyond care, isolation, and hope. It is a period that gives some of our old-school home health remedies their origins, born in an age when there were few other tools for an infectious disease sweeping through a household. What changed was not that people started caring more for sick children. It was that, one disease at a time, prevention finally became possible.

The chart flattens a great deal of human history into single rows. It is worth pausing on a few of them.

Smallpox: The One Disease We Ever Erased

Smallpox holds a unique place in this story because it is the only human disease ever driven to true extinction. After a global vaccination campaign, the World Health Organization certified smallpox as eradicated worldwide in 1980 — the first and, so far, only time humanity has permanently eliminated one of its infectious diseases from the planet. The last naturally occurring U.S. case had already appeared decades earlier, in 1949. Today the smallpox row reads simply: zero, and it stays zero without any ongoing vaccination at all.

Polio: From Summer Dread to the Brink of Zero

For mid-century American families, polio was the disease that turned summer into a season of fear, closing swimming pools and filling hospital wards with paralyzed children. In the years before the vaccine, the country saw an average of more than 16,000 paralytic polio cases annually. The last case of endemic wild polio in the United States occurred in 1979. In the chart, paralytic polio now sits at zero to one case — a decline so close to total that the remaining sliver is almost a rounding error.

Measles: The Cautionary Row

Measles is the row that most rewards a closer look, because it captures both the triumph and the fragility of this whole story. Before the vaccine, the United States recorded an estimated 530,217 cases in a typical year. By 2000, sustained transmission had been interrupted so thoroughly that the Centers for Disease Control and Prevention declared measles eliminated in the country, meaning it was no longer spreading continuously within U.S. borders. By 2022, reported cases had fallen to just 121.

It would be a mistake, though, to read measles as a mild inconvenience simply because the numbers grew small. Measles is not an ordinary respiratory bug, and it behaves very differently from the everyday illnesses covered in a guide like cold versus flu versus COVID versus RSV. About one in five unvaccinated people who catch measles in the United States end up hospitalized, and serious complications can include pneumonia and brain inflammation. The small number in the chart reflects how effectively the disease was held down, not how gentle it is.

Diphtheria, Whooping Cough, and the Rest

The remaining rows fill in the same picture from different angles. Diphtheria, which once killed thousands of children a year, is down to about a single reported case. Mumps fell from more than 162,000 cases to a few hundred. Rubella, dangerous mainly for the birth defects it causes when it infects pregnant women, dropped from nearly 48,000 cases to single digits, and the United States declared it eliminated in 2004. Whooping cough and tetanus show slightly smaller declines — 98% and 96% — but from a human standpoint, those are still enormous reductions in suffering.

A fair question sits underneath this chart: how do we know the vaccines did the heavy lifting? After all, the twentieth century also brought cleaner water, better nutrition, and stronger hospitals, and those improvements genuinely reduced deaths from many infectious diseases well before vaccines arrived.

The honest answer is that both things are true, but they show up in different measurements. Sanitation and medical care helped bring down deaths gradually over decades. The steep collapse in the number of cases, however, tracks closely with the arrival of each specific vaccine — disease by disease, with the timing lining up again and again. Measles and Hib, for instance, stayed common right up until their vaccines appeared, even in a country that already had modern plumbing and hospitals. That alignment is why public health researchers attribute the case-count drops in the chart specifically to vaccination.

The mechanism behind those drops works on two levels at once. A vaccine protects the individual who receives it, lowering their own chance of infection. But once enough people in a community are protected, the disease also struggles to find new hosts to jump to, which shields people who cannot be vaccinated — newborns, or those with weakened immune systems. This second layer is community immunity, sometimes called herd immunity, and it is the reason population-wide coverage matters far beyond any one person's choice.

How much coverage a community needs depends on how contagious the disease is. Measles is the demanding case: it is among the most contagious illnesses known, with one infected person capable of spreading it to a dozen or more susceptible people. Because of that, interrupting measles typically requires roughly 95% of a community to be protected with two doses of MMR vaccine, a threshold explained by the History of Vaccines project at the College of Physicians of Philadelphia. Less contagious diseases can be controlled at lower coverage levels.

That same resource draws a distinction worth keeping straight, because the three words are easy to blur:

• Control means reducing a disease to a level a community finds acceptable.
• Elimination means reducing it to zero continuous local spread in a defined area — measles in the United States in 2000, for example. Imported cases can still appear, and the disease still exists elsewhere in the world.
• Eradication means wiping it out permanently across the entire globe, so that no control measures are needed at all. Smallpox is the only human disease to reach that final category.

The distinction matters for what comes next. When a disease is eliminated rather than eradicated, its low place on the chart is not permanent. It is maintained — and maintenance can lapse. Those low numbers also translate into avoided suffering on a scale that is easy to underestimate; complications like pneumonia, which a dedicated overview of pneumonia describes in more detail, are exactly the outcomes that high coverage keeps rare.

Here is the twist the static chart cannot capture: the near-zero lines are only as durable as the coverage holding them there, and that coverage has been slipping.

The clearest warning sign is measles. In 2025, the United States recorded roughly 2,288 confirmed measles cases — the highest annual total since 1991, according to CDC surveillance summarized by the American Academy of Pediatrics. The outbreak that drove much of it began in Texas in early 2025 and spread across dozens of states. As of July 2026, the year has already surpassed the full 2025 total, making it the worst stretch for measles in at least 35 years. (Because these counts change week to week, they are best read as a moving snapshot rather than a final number.)

Underneath the outbreaks sits a quieter number. National MMR coverage among kindergartners was 92.5% for the 2024–25 school year, according to CDC data highlighted by the health policy organization KFF — below the roughly 95% needed to reliably stop measles from spreading. That gap of just a few percentage points sounds trivial, yet for a disease as contagious as measles, it is the difference between a stray imported case that fizzles out and a chain of transmission that catches fire. Coverage also varies from place to place, which is why outbreaks tend to cluster in communities where local protection has dropped well below the national average.

The stakes now reach all the way back to the chart itself. Because measles elimination is assessed regionally, an expert commission tied to the Pan American Health Organization periodically reviews whether a country has sustained enough ongoing transmission to lose its elimination status. The United States, which earned that status in 2000, faces such a review in late 2026. For readers who want to follow how the current situation is unfolding, our companion report on why 2026 already outpaced last year tracks the latest developments.

None of this rewrites the century of progress the chart records. The vaccines work exactly as well as they always did; the diseases have not grown stronger. What has changed is the share of people carrying the protection that keeps those lines flat. The chart's first hundred years are a settled achievement. Its next chapter is the one variable still genuinely in play — decided not by the viruses, but by how many people stay protected against them.