Luke Voytas is a pediatrician and author in Portland, Oregon. His posts combine research and common sense to help parents be calm and confident in raising their kids.

Remember Smallpox? Me Neither.

Remember Smallpox? Me Neither.

Smallpox was already eliminated from the earth by the time I was born in 1979. I never knew much about it – I remember seeing some pictures of some really unhappy-looking kids with bumps all over them, and I think I saw a movie where U.S. soldiers gave blankets to Native Americans that were soaked in the virus. That’s about it.

But as vaccine hesitation and suspicion grow, maybe we need to know about smallpox now more than ever.

Here’s a quick trivia question: what killed more people in the twentieth century – every single war (and there were a lot of them) or smallpox?

Smallpox. And it wasn’t even close. War killed a horrifying 100 million people and smallpox is estimated to have killed an incomprehensible 300 million people in the century we were all born in..

There’s a lot of he said/she said in vaccine debates. Plenty of speculation and fear. No doubt we have great data to prove the safety and effectiveness of vaccines, but it’s clear that data isn’t a very good driver of human behavior. Stories, on the other hand, work much better. Unfortunately, those working to sway parents away from vaccines are winning the battle on stories. They’ve filled our dialogue space with stories of children devastated by vaccines, children who abruptly develop autism after an MMR vaccine, or healthy kids who develop chronic illnesses after getting “too many” vaccines at once.

I’m not saying these stories are true, but they’re out there and they’re powerful. They create doubt and fear, and those emotions prompt many good parents to avoid vaccines.

It’s probably not quite as moving to tell people, “I inoculated my daughter with the Prevnar vaccine the other day, dramatically slashing her susceptibility to invasive pneumonococcal disease!” Even with an awesome word like “slashing,” it doesn’t create a very dramatic impression.

There are plenty of good stories that can promote vaccines, though. In my last post I wrote about the measles outbreak in my county, for example, and the changes in behavior that have accompanied it.

But the story of smallpox is crazy. Just unbelievable. And even though it’s relatively recent it has largely faded into history.

In smallpox we have a complete, wrapped up, end-to-end example of a vaccination program. It’s done, a finished body of work. We can look at the pluses and minuses and judge the entire process. We have everything we need to answer the question, “What happened with smallpox?” And maybe we can apply to that to other vaccine efforts today that aren’t yet complete. I would argue the story of how we conquered smallpox is one of the most triumphant stories that’s rarely told.

Smallpox was an illness caused by the variola virus, and you could think of it as influenza on steroids. It would cause several weeks of fevers, shaking, vomiting, and severe body aches, with pus-filled bumps developing a few days into the illness. About 30% of those who developed the disease died a horrific death, although this rate was far higher for children. Many of those who survived became blind.

The virus is at least 3000 years old, because they found smallpox sores on an Egyptian mummy from that time. There are good descriptions of the disease from China in the fourth century and India in the seventh. The crusades helped spread it to Europe by the 11th century, and colonization later spread it to the Americas.

Smallpox even helped reshape the political landscape of the world. It paved the way for European conquest by killing nearly 90% of the native population of the Americas and devastating the Incan and Aztec empires. Lost in the history of the American Revolutionary War was a smallpox outbreak which killed over 100,000 people and maimed or blinded many more. (1)

From early on, people noticed that those who did survive smallpox never got it again. So many cultures tried to give themselves small exposures – hopefully enough to get protected but not enough to get the full illness. They would scrape some pus into the skin, wear the shirt of an infected person, or sleep next to them. (2) This process of “variolation” was risky (I’m guessing results were mixed) but the disease was so terrible that people were desperate.

Edward Jenner (1749-1823) was a brilliant English doctor who finally found a real solution. There was a very similar but much milder disease called cowpox, which was caused by the vaccinia (that name looks vaguely familiar, eh?) virus. Jenner realized that milkmaids who had gotten cowpox never got smallpox. So he did an experiment that would change the world. He took some cowpox virus from a sore on a milkmaid’s arm and scratched into the arm of a 9 year-old boy named James Phipps (remember that – it might win you a trivia contest some day). (3) He noticed that small blisters formed near the scratches. He then exposed the boy to smallpox multiple time months later and found that he did not develop the disease.

The ethics of this experiment are murky at best, but it was the first time we learned to inject a small, controlled amount of a virus to give our bodies protection against a much worse disease. Since cowpox was a relatively mild disease, this was also far less risky than previous efforts using the actual smallpox virus.

Jenner’s discovery took a while to catch on, but European countries began to make vaccination mandatory by the early nineteenth century. Progress was slow, because doctors had to harvest some pus from the blisters of a recently vaccinated person’s arm to use for the next person. Also, the vaccine didn’t do well in tropical temperatures.

Nevertheless, by 1949 smallpox was eliminated in the United States. By the 1960’s researchers developed a freeze-dried vaccine that could be shipped around the world and a bifurcated needle that delivered it more effectively. In 1967 the World Health Organization (WHO) started an “Intensified Eradication Program” to finish off the virus in the developing world. 15 million people were still infected per year at the start of that effort, and 10 years later that number was zero. The United States and the Soviet Union worked together to spearhead these efforts in the thick of the Cold War. The last naturally occurring case of smallpox was in 1977 in Somalia.

This wasn’t just a massive triumph of science. In a century that featured the most intense conflict in human history, it provides a compelling example of countries working together to solve a problem that affects us all (climate change, anyone?).

The WHO intended for the U.S. and Russia to each have a small stockpile of the virus for research purposes, with a plan of destroying these supplies on June 30, 1999 and truly eliminating the virus from existence. Sadly, just two months prior to this, the U.S. pulled out after learning that there might be some secret supplies in the hands of unsavory actors who could use them for bioterrorism. (4) Our government still maintains a large smallpox vaccine supply that’s ready to go if needed.

All I want to do is interject some history into the vaccine debate. Factual, finished history. How did smallpox, one of the worst diseases of all time, go away? Did it naturally run its course? Did we evolve to outsmart it? Or did we methodically and painstakingly inject a small amount of a very similar live vaccine into nearly everyone in the entire world so that their bodies built a response of antibodies to blast any smallpox they were exposed to? What happened? What if some of those people who got vaccinated got a fever, or some redness around the vaccination site, or even a nasty rash? What if a few of the people who got vaccinated still got smallpox? What about that? Is that too steep a price to pay to prevent another 300 million deaths this century?

I’m just asking the question. It seems quite relevant to look at the history of a completed vaccination project when there is so much anxiety and uncertainty about the projects currently underway. When we add up the pluses and the minuses, the prevention of hundreds of millions of deaths versus the pain of the shots and the occasional vaccine reactions, what can we conclude?

A common concern raised by parents today is the risk of side effects weighed against the prevention of diseases such as polio and measles that have become super rare. Again, the story of smallpox can help give us some perspective. The smallpox vaccine was not very sophisticated. It was less safe than the vaccines we use today. Fever, aches, and fatigue were common. One study found that 1 out of 3 people actually had to miss work or school due to side effects. (4) Some people even developed full blown vaccinia (not as bad as smallpox but still no fun).

What about those American parents in the 1950s and 60’s who were asked to vaccinate their kids against smallpox even though it was gone from the United States? Was there a better chance of them getting a side effect than the disease? Of course. But those parents were well aware of the horrors of smallpox. Some of their own parents had it, and millions were still dying from it across the globe every year. This was the only way to get rid of it forever.

Measles, mumps, rubella, and polio are terrible illnesses, though certainly not as devastating as smallpox. But we have to step outside of our social media circles when we think about vaccines and look to history. Why would we not? Just like we can ask about what happened with smallpox, can we ask what’s happened with measles? Shouldn’t we ask what’s happened with measles?

It’s estimated that 200 million people have died from measles since 1855. (5) Now that number is down to 110,000 a year. How did that happen? Of course we do a better job of taking care of sick kids than we used to, but that doesn’t explain everything. Is the world better off from that vaccine or not? Even if your kids can get a rash or a fever from the vaccine, why are we close to eliminating it from the earth?

I saw an anti-vaccine post recently in which the author said that the natural state of our bodies is to heal, if we just get out of the way. What an absurd, ignorant, and privileged viewpoint - ironically made possible only by the impact of vaccines. For 99.99% of human history, the natural state of our bodies has been to die early and painfully due to smallpox, measles, influenza, and other viral terrors.

So the next time you find yourself in a vaccine debate, forget about data. Forget about studies. Just ask one simple question:

What about smallpox?

1. Elizabeth Fenn, Pox Americana: The Great Smallpox Epidemic of 1775-1782, (New York: Hill and Wang, 2001).

2. Gross CP, Sepkowitz KA . The myth of the medical breakthrough: smallpox, vaccination, and Jenner reconsidered., Int J Infect Dis. 1998 Jul-Sep; 3(1):54-60.

3. “History of Smallpox,” Centers for Disease Control and Prevention, last updated August 30, 2016,

4. Frey SE et al, National Institute of Allergy and Infectious Disease Smallpox Vaccine Study Group. Clinical responses to undiluted and diluted smallpox vaccine. N Engl J Med. 2002;346:1265-1274.

5. Torrey EF and Yolken RH. Their bugs are worse than their bite. Washington Post. 2005. April 3, p. B01.

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