When was Target Zero Day?

It was a red-letter day in the history of medicine – ‘Target Zero Day’, 8 May 1980, signified the complete eradication of smallpox, a terrifying scourge that had previously killed one in 12 worldwide. Smallpox was untreatable but, luckily, it turned out that vaccination provided good protection – and that intensive immunisation could exterminate the smallpox virus by blocking its spread.


According to legend, vaccination was invented by Dr Edward Jenner of Berkeley, Gloucestershire. Jenner showed that healthy children inoculated with cowpox, a mild infection of cattle, could not catch smallpox. He was supposedly inspired by a comment from a local milkmaid, but there is evidence the idea came from a medical friend, John Fewster, who had experimented with cowpox. Vaccination goes back even further. In 1774, a Dorset farmer, Benjamin Jesty, inoculated his wife and sons with cowpox; Jesty’s experiments were belatedly publicised in 1803, by doctors trying to undermine Jenner’s reputation. Nonetheless, Jenner deserves credit for catapulting vaccination into the medical main- stream with his Inquiry into the Causes and Effects of the Variolae Vaccinae, or Cow-Pox, published in 1798.

On the podcast | Gareth Williams explores previous efforts to combat lethal diseases, from smallpox to polio:

How was Smallpox eradicated?

In 1966, 160 years after the prophecy that vaccination would exterminate the disease, the World Health Organization launched its Smallpox Eradication Programme. This heroic 11-year drive was masterminded by two American public health doctors, DA Henderson and Bill Foege. Their adversaries included both geopolitical barriers, and colleagues at the WHO who wanted the smallpox budget. One WHO apparatchik even promised to eat a tyre if smallpox was eradicated; Henderson duly promised to send him the tyre and wished him bon appétit. But Henderson and Foege’s hard work paid off – three years after the last smallpox case was notified (to make sure no outbreaks had been missed) Target Zero Day was declared.

Why should we remember it today?

So 40 years on, why should we remember Target Zero Day? First, to celebrate a triumph of preventative medicine and freedom from a brutal disease. We must also remember the victims of smallpox. In 1914, a Canadian professor warned against forgetting smallpox, which was fast disappearing from North America. It went on to kill at least another 250 million people – three times more than both world wars combined.

Target Zero Day also reminds us of unconquered infections, including polio, measles, malaria, and of course the coronavirus Covid-19. As I wrote, the WHO has upgraded Covid-19 to a pandemic, the NHS is on a war footing and stock markets are wobbling. So far, though, the virus’s impact is modest compared with smallpox. So let’s recognise Target Zero Day for what it is: a milestone in world history and a monument to the art of the possible.

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Gareth Williams is emeritus professor and former dean of medicine at the University of Bristol, and the author of Angel of Death: The Story of Smallpox (Palgrave Macmillan, 2010)


This article first appeared in the May 2020 issue of BBC History Magazine