Vaccines: Success Story of the Century

by Brian Dunning
March 25, 2025

It seems incredible to still have to say it, but vaccines save lives. The data could not possibly be any more stark, but nevertheless, the US (and the rest of the world in general) is seeing an ever-increasing level of vaccine denial. Claims that vaccines cause more harm than good are shouted through megaphones. US states are enacting anti-vaccine legislation with reckless abandon. So today we're going to take a stroll through the garden of vaccine success stories, and try to counter all that disinformation with a gala of the very best things vaccines have done for us.

2024 marked the 50th anniversary of the World Health Organization's Expanded Programme on Immunization (EPI), launched in 1974 to try and bring the benefits of vaccinations to populations all over the globe. A group of authors published an assessment of the program's success in The Lancet in May 2024. They found that during just those 50 years, vaccines saved an estimated 154 million lives.

Here's a stat from that study. Because most vaccine-preventable deaths are of young children, cutting their lives short by an average of 66 years, those 154 million lives saved equate to 10.2 billion years of full health gained. If you are one who prefers to look at these things not in terms of the human cost but in the monetary cost, that's one full year of the entire planet's economic productivity.

But however you prefer to view it, let's now celebrate the top ten vaccine success stories.

10. Yellow Fever: 557,000 lives saved (1974-2024)

Yellow fever came and went in waves of epidemics, and it averaged about 80,000 people killed each year around the world. In the United States, as many as 135 outbreaks in the 18th and 19th centuries killed up to 20,000 Americans each. It's a horrible disease; depending on various factors it can be fatal in as many as 50% of cases.

Work in the 1930s finally resulted in an effective vaccine — in fact it's the same as we still use today; it's one of the oldest vaccines. Today nobody dies of yellow fever in the US, due to the vaccine and to mosquito control, so the vaccine is no longer given; unless you're traveling someplace where it's still endemic, like Africa or South America. Those other regions still suffer some 60 to 75 thousand deaths a year.

9. Polio: 1,570,000 lives saved (1974-2024)

Before Jonas Salk famously invented the vaccine, there were approximately half a million polio cases around the world annually, which killed an average of about 35,000 children every year. And it left far more permanently crippled, or worse, living out their lives in iron lungs.

But then Jonas Salk saved the day in 1955, and a few years later an oral vaccine came out. These terminated polio by 1979 in the United States, when the last known case was reported. Except there was a complication. That oral vaccine used various strains of live but weakened virus, and it's safe and effective; except in cases where not enough other people have been vaccinated, and that weakened strain can then spread in what's called VDPV, or vaccine-derived poliovirus. So we don't use that version anymore since 2000, just the inactivated poliovirus vaccine. Worldwide there were 689 cases of VDPD — a far cry from half a million.

8. Pneumococcus: 1,623,000 lives saved (1974-2024)

The bacterium Streptococcus pneumoniae causes pneumococcal disease, which can result in pneumonia, meningitis, and sepsis. These in turn can result in brain damage, deafness, loss of a limb, or death. So you don't want it.

The vaccine was first licensed in 1977, and improved in 1983. Throughout the 2000s, new versions were introduced for young children, adults, and adults over 65. Prior to that, pneumococcus caused 14.5 million cases a year in children under 5, some 18% of which resulted in severe pneumonia, and killed 541,000 children under 5 each year. Before those age-specific vaccines were introduced in the US, we lost 6,000 children under 5 each year, and 22,000 people across all age groups. Since then, there are now only about 3,700 deaths in the US each year, mostly in adults over 65; and an 89% reduction in pediatric pneumococcal meningitis deaths.

One interesting little factoid is that every $1 invested in this vaccine yields $7.7 in economic benefits, through reduced healthcare costs and productivity gains.

7. Haemophilus Influenzae type B: 2,858,000 lives saved (1974-2024)

A lot of Americans might not have even heard of this, because the vaccine has virtually wiped it out in this country. This is one of the regularly scheduled vaccines for young children in the United States, given in three or four doses beginning at about six weeks of age. Haemophilus influenzae type B, or Hib, is a bacterium that causes Hib disease, usually resulting in either meningitis or pneumonia. It could cause blindness, deafness, learning disabilities, or death.

Prior to the vaccine, about 20,000 American children developed a serious illness each year, and 5% of them died; 20% were permanently debilitated. Nearly all cases were in children under the age of five. The first vaccine was developed in 1985, with an improved version introduced in 1987. Cases in the United States have dropped by more than 99.9%.

But globally, that number only went down by 80%, from over 8 million serious cases and 370,000 deaths every year, to about one million cases and about 30,000 deaths. The reason? Very slow uptake of the vaccine, especially among low income countries. Full vaccine coverage is currently reaching only about three quarters of children worldwide.

6. Tuberculosis: 10,902,000 lives saved (1974-2024)

Famously and historically known as The Consumption, tuberculosis remains today as the world's top infectious killer. 10 million people worldwide are infected every year, and 1.5 million of them die. Every year. Half of them are in just eight low-income countries. In the 1800s it was responsible for one quarter of all deaths.

But if it seems odd that this many people are still dying from it every year, yet we're citing it as a vaccine superstar, the reason is twofold: First, a huge number of people get TB every year; and second, the vaccine (called BCG) is among the least effective. It's only from 0% to 80% effective on individuals at preventing an infection; but if you do get the infection, it reduces the likelihood you will become seriously ill by 60%. So it's not magical, but it's certainly a lot better than nothing.

Needless to say, at least five new vaccines are under development that we hope will be far more effective.

5. Pertussis: 13,155,000 lives saved (1974-2024)

AKA whooping cough, pertussis is endemic worldwide. Epidemics of it cycle every two to five years in every country, so numbers change a lot year to year. Before the vaccine, the United States averaged 178,000 cases per year, 93% of them in children under 10. But since the vaccine's introduction in 1938 and several improvements over subsequent decades, cases in the US are way down, averaging 1,000 to 30,000 a year as those cyclical epidemics ebb and flow.

Today there are an estimated 160,000 deaths annually worldwide, almost all of them in developing nations, especially Africa, where uptake of the vaccine is extremely low. The United States is one of the very few nations with an increasing rate of incidence, due entirely to fewer vaccines being administered by vaccine-hesitant parents.

4. COVID-19: 2,500,000 - 20,000,000 lives saved (all time)

Why such an enormous range of nearly a full order of magnitude? The short reason is that it's been too soon. I read estimates ranging from 1 million to 25 million, and one reason for that is that different studies considered different populations, different date ranges, even different strains of the virus.

These studies are also complicated by whether indirect effects should be included. When lots of people are vaccinated, unvaccinated people are far less likely to catch it from someone. Do you count those unvaccinated people as having had their lives saved?

It's also complicated by excess mortality measures, and whether they should be included. These can include questions like whether you count the victims of a fire which wasn't put out because firemen were quarantined. The hospital was overwhelmed and people died from other conditions because they weren't adequately treated. Even things like there were no traffic deaths that day, which there otherwise would have been, because the lockdowns kept everyone off the road.

In time we'll be able to look back with clearer vision and have firmer numbers. For now, about the one thing where there's a clear consensus is that the vast majority of lives saved, some 95% of them, were of people over 60.

3. Tetanus: 27,955,000 lives saved (1974-2024)

Data is scarce on how many died of tetanus before the vaccine became widespread, because the majority of the deaths were neonatal and were in regions where there was already high infant mortality. The vaccine had been around since the early 20th century, but uptake on it remained very low throughout most of the century.

In 1999, UNICEF, the World Health Organization, and the UN Population Fund launched a program called the Maternal and Neonatal Tetanus Elimination Initiative with the goal of vaccinating enough people to get the neonatal tetanus incidence rate down to 1 in 1,000 live births. As of today, only 11 nations have yet to achieve that.

That program has brought down global newborn deaths from an estimated 787,000 in 1988, to 25,000 in 2018. That's a 97% reduction.

2. Measles: 93,712,000 lives saved (1974-2024)

Measles. Ah yes, the thing that really shouldn't be headlines in 2025, but somehow is. Because vaccine disinformation.

Measles used to be a leading cause of childhood mortality, with six million children a year dying from it before the vaccine. 100 million children got it every year (4 million of those in the United States); those who survived were often left with pneumonia, deafness, or encephalitis.

Then in 1963 the first vaccine was licensed. This has been one of the great success stories. Just ten years after its introduction, measles cases in the US dropped by 99.8% to just 10,000. In the year 2000, measles was declared eradicated in the United States.

But then 2025 happened, with widespread growth in public vaccine and science denial, led by public figures like Robert F. Kennedy Jr. As parents are increasingly refusing to allow their children to receive the vaccine, citing their religious or ideological objections to public health, children are dying in the United States again from measles for the first time in a quarter of a century.

1. Smallpox: 500,000,000 lives saved (all time)

It is the king of all vaccine success stories. Smallpox was one of the deadliest diseases humankind has ever faced; it killed a third of everyone who got it and spread easily. It is now officially eradicated worldwide — thanks entirely to the vaccine. It remains the only disease we have so far managed to completely wipe off the face of the Earth, with the last known case having occurred in 1977. The World Health Organization declared it eradicated in 1980.

We don't know how many hundreds of millions of people died of smallpox before; it's even been found in Egyptian mummies as early as 1350 BCE. In the last century of its existence, it's estimated to have killed 500 million people. Extrapolate that back as many centuries as you like.

For much of smallpox's multi-millennium history, people around the world were attempting to inoculate against it, even with some success. They would grind up scabs from people who had survived smallpox and took the powder up their noses. They would lance the boils of animals with cowpox and needle it into people's arms. Hearing that this tended to be successful, in 1796 Dr. Edward Jenner injected a healthy boy with cowpox, waited two months, then injected him with smallpox. The boy never got sick, and the world's first vaccine was born.

By the early 1800s, smallpox epidemics in most countries stopped. By the early 1900s, there were almost no more cases anywhere. And now it's gone. If we can do it once, we can do it again.

Vaccines not only save lives; they save enormous amounts of money in saved healthcare costs. In 2011, the CDC issued a report finding that childhood vaccination prevents approximately 42,000 deaths in the United States every year, prevents 20 million cases of disease every year, and saves $20 billion in direct costs and $100 billion in total societal costs (in 2025 dollars). So it's absolutely clear from the data that people who seek ideological or other exemptions from their children's vaccines are not only putting their children's lives at a very real risk, they are costing themselves — and all the rest of us — quite a lot of money in caring for unvaccinated children who are stricken with vaccine-preventable disease.

By Brian Dunning
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