On May 8, 1980, more than two years after the last known case, the World Health Assembly formally declared the world free of smallpox.
It’s far from the most celebrated date on the calendar, but Smallpox Eradication Day marks what I think is one of the most meaningful achievements in human history.
Though increasingly few people have any living memory of it, smallpox was an utterly nightmarish scourge. It was more contagious than Covid-19 — spreading easily through the air and lingering to infect people even after the sick person had gone — and killed 30 percent of those it infected. In the 20th century alone, it is estimated to have killed between 300 million and 500 million people.
So while May 8 isn’t a conventional holiday, in my house we celebrate it as one — with piñatas shaped like the smallpox virus, presents for the kids, a cookout, and a big party. Our kids are pretty young, and as far as they’re concerned Smallpox Eradication Day is one of the big landmark holidays of the year alongside Halloween and Christmas.
It’s a good moment to celebrate a huge human achievement, think about how far we’ve come, and appreciate the people who made it happen. I want to encourage readers to celebrate it themselves or at least set aside a moment to take pride in what humanity achieved.
How we beat smallpox
Ever since the immunizing effects of a milder cowpox infection had been discovered in 1796, countries battled to make inoculation against smallpox available. The US Congress passed legislation to make a smallpox vaccine available in 1813.
By the 20th century, vaccination in rich countries had mostly stamped the disease down to occasional outbreaks. But as international travel got more common, those occasional outbreaks got less occasional — and in any event, in poorer countries, where vaccines were far less available, smallpox was still killing tens of millions.
In the 1950s, the conversation about worldwide eradication began in earnest. In the postwar moment, new international institutions had been built that could conceivably coordinate an effort on that scale. Soviet virologist Viktor Zhdanov was the first to make a credible public call to make smallpox eradication happen and convinced the World Health Assembly to accept his proposal. The effort had thousands of contributors, with particular credit due to the stubborn leadership of US epidemiologists Donald Henderson and Bill Foege.
The newly founded World Health Organization (WHO) took the lead. Doctors, nurses, and public health officials worked around the world to administer vaccinations in remote areas and trace the contacts of known cases. The effort was controversial at first — many people thought it couldn’t possibly succeed — but it gained momentum as country after country managed to clear the virus for good.
One key innovation was, counterintuitively, not trying to vaccinate literally everyone on the planet. Instead, health officials focused on “ring vaccination”: inoculating all people who may have come into contact with an infected person, a strategy that was helped by the fact that smallpox vaccination can be effective even after a potential exposure. On December 9, 1979, the disease was confirmed to have been eradicated, with the World Health Assembly making the declaration official five months later. (We celebrate the May date rather than the December one just because December isn’t a good time for a new celebratory cookout holiday and May is.)
Smallpox should only be the start
A lot of factors combined to make smallpox eradication possible when eradicating many other diseases has been much harder. Smallpox was incredibly contagious and incredibly deadly, but vaccination was near-perfectly effective against it, the virus had no animal reservoir in which it could hide, and it was not a fast-evolving pathogen that could evade our defenses. We got lucky, in some ways, that this particular deadly killer was vulnerable in a way many others have proven not to be.
But it wasn’t just luck. It took courage and determination, and grindingly difficult work, from thousands of people all around the world, ranging from infectious disease specialists to front-line care workers administering vaccines at great personal risk. Smallpox, in the ultra-violent 20th century, killed more people than war. Ending it took a decade-long logistical effort on approximately the same scale as a war, only with this campaign, lives were not taken, they were saved.
Today, smallpox virus samples exist in only two locations: the Centers for Disease Control and Prevention in Atlanta and the VECTOR Institute in Koltsovo, Russia. But as my Vox colleague Jen Kirby wrote in a detailed feature last week, there are still fears that terror groups or even states could turn smallpox into a weapon once more.
New advances in synthetic biology make it possible for deadly viruses to be synthesized from scratch, even as the underfunded, 50-year-old Biological Weapons Convention struggles to keep up with the science. Eradicating smallpox took work; keeping the world safe from it, and from new biological threats on the horizon, will require even more. It doesn’t help that the international body charged with keeping the world free of bioweapons has an annual budget that’s smaller than that of the average McDonald’s franchise. But that should only make us better appreciate what Henderson, Zhdanov, and their comrades-in-arms managed to achieve.
Each year around now, I often think of the British World War I poet Wilfred Owen, who died in France in 1918 at the age of 25, just one week before the armistice. One of his most famous poems, “The Next War,” ends with these lines:
That poem is one I reread on Smallpox Eradication Day, along with Jai Dhyani’s “500 Million, but Not a Single One More.” And then we give the kids cake and piñatas and water balloons, because it’s meant to be a joyous holiday, not a solemn one: a celebration of what humanity can achieve, and a reminder that sometimes, in the war on Death, we win.
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