Eradication of Smallpox (1967–1980): How a Disease Was Ended

The eradication of smallpox is the only time humanity has wiped out a disease that infected people. Between 1967 and 1977 the World Health Organization’s Intensified Smallpox Eradication Programme tracked down the last chains of infection across Asia, Africa and South America, and on 8 May 1980 the World Health Assembly declared the world free of smallpox. The campaign changed public health and showed what international cooperation could achieve, even at the height of the Cold War.

Background: an ancient killer

Smallpox was caused by the variola virus and spread from person to person, mostly through droplets when people were in close contact. It caused fever and a distinctive rash that turned into deep, pus-filled blisters. The common form, variola major, killed roughly 30 per cent of those infected, and many survivors were left scarred or blind. A milder form, variola minor, killed around 1 per cent.

The disease had shaped history for thousands of years. It devastated the Indigenous peoples of the Americas after European contact, including during the smallpox epidemic in Tenochtitlan, and it killed kings and commoners alike in Europe and Asia. In the 20th century alone it is commonly estimated to have caused around 300 million deaths.

Protection came in stages. Inoculation with material from smallpox sores, long practised in Asia and Africa, was popularised in Britain by Lady Mary Wortley Montagu in the 1720s. In 1796 Edward Jenner showed that cowpox could protect against smallpox, the origin of vaccination. By the mid-20th century vaccination had eliminated smallpox from Europe and North America, but it remained widespread elsewhere.

Why eradication seemed possible

Several features made smallpox a good target. Humans were the only host, so there was no animal reservoir from which it could return. Almost every infection produced a visible rash, which made cases easy to recognise. Survivors were immune for life, and the vaccine was cheap, stable and highly effective.

In 1958 the Soviet deputy health minister Viktor Zhdanov proposed a global eradication campaign to the World Health Assembly, which adopted the goal in 1959. Progress was slow. The programme had little money, and mass vaccination struggled in hot climates where liquid vaccine spoiled. By the mid-1960s smallpox was still endemic in more than 30 countries, with an estimated 10 to 15 million cases and around 2 million deaths every year.

The Intensified Programme

In 1966 the World Health Assembly voted for a renewed, better-funded effort. The Intensified Smallpox Eradication Programme began on 1 January 1967, with a ten-year target. It was led from WHO headquarters in Geneva by Donald A. Henderson, an epidemiologist seconded from the United States Communicable Disease Center (now the Centers for Disease Control and Prevention, CDC).

The programme depended on national health workers in each endemic country, supported by a relatively small number of international staff. The United States and the Soviet Union were among the largest contributors, and the Soviet Union donated very large quantities of vaccine. Much of the cost was borne by the endemic countries themselves.

Two technical advances helped. Freeze-dried vaccine kept its potency without refrigeration, and it was produced to new quality standards. The bifurcated needle, a simple two-pronged steel needle, held a measured drop of vaccine and could be used by volunteers after minimal training. It needed far less vaccine than older methods and could be sterilised and reused.

Surveillance and ring vaccination

The decisive change was in strategy. Early campaigns aimed to vaccinate around 80 per cent of a population, but outbreaks continued where coverage was uneven. In December 1966, in eastern Nigeria, the American epidemiologist William Foege faced a shortage of vaccine. He and his colleagues concentrated on finding cases and vaccinating people around them, and the outbreak was stopped even though most of the population was unvaccinated.

This approach, called surveillance and containment and often described as ring vaccination, became the core of the programme. Teams searched for cases, isolated patients and vaccinated household members, neighbours and other contacts. Rewards were offered for reporting cases, and workers carried picture cards showing the rash so that villagers could recognise it.

The method was most dramatic in South Asia. India and its neighbours mounted huge house-to-house searches in 1973 and 1974, at times involving well over 100,000 health workers. Outbreaks were mapped and contained one by one. India recorded its last case in May 1975.

The final cases

Smallpox ended region by region. West and Central Africa were cleared by 1970, Brazil recorded its last case in 1971 and Indonesia in 1972. The last case of variola major in the world was a young girl, Rahima Banu, on Bhola Island in Bangladesh, in October 1975. She survived.

The final battleground was the Horn of Africa. In Ethiopia, civil conflict, mountainous terrain and nomadic populations made the work slow and dangerous. The virus then spread into Somalia, where an epidemic of variola minor in 1976 and 1977 required a large emergency campaign.

On 26 October 1977, a rash appeared on Ali Maow Maalin, a 23-year-old hospital cook in the port town of Merca, Somalia. He had been briefly exposed while showing a vehicle carrying two infected patients the way to an isolation camp. He recovered, and every one of his contacts was traced and vaccinated. He was the last person known to have caught smallpox naturally. Later in life he worked as a volunteer in the campaign against polio.

The Birmingham tragedy

One more outbreak followed. In August 1978 Janet Parker, a medical photographer at the University of Birmingham medical school in England, fell ill with smallpox. She worked in a room above a laboratory that handled the virus, and she died on 11 September 1978. Her mother also became infected but recovered. Parker is the last person known to have died of smallpox.

The episode led to tighter controls. Laboratories were asked to destroy their stocks or transfer them, and eventually only two official repositories remained: the CDC in Atlanta and the VECTOR research centre in Koltsovo, Russia.

Certification

Declaring eradication required proof that the disease had truly gone. Teams continued searching for at least two years after the last case in each country, investigated every reported rash and tested specimens in reference laboratories. In December 1979 an independent Global Commission, chaired by the Australian virologist Frank Fenner, certified that smallpox had been eradicated.

On 8 May 1980 the 33rd World Health Assembly formally accepted the finding and declared that the world and all its peoples had won freedom from smallpox. Henderson had left Geneva in 1977, and his Japanese successor, Isao Arita, led the programme through certification.

By the numbers

Myths and facts

A common belief is that smallpox was beaten by vaccinating everyone. In fact, the programme succeeded largely by finding and containing outbreaks, and some areas were cleared while vaccination coverage remained incomplete. Mass vaccination still mattered, but surveillance was the key.

Another misconception is that eradication was achieved by wealthy nations alone. Most of the field work and much of the funding came from health services in the endemic countries, from Ethiopia and Somalia to India, Bangladesh and Indonesia.

Timeline

• 1959: The World Health Assembly adopts the goal of global smallpox eradication.
• 1966, December: William Foege’s team in eastern Nigeria shows that surveillance and containment can stop outbreaks.
• 1967, 1 January: The Intensified Smallpox Eradication Programme begins under Donald A. Henderson.
• 1975, May: India records its last case of smallpox.
• 1975, October: Rahima Banu in Bangladesh becomes the last known case of variola major.
• 1977, 26 October: Rash appears on Ali Maow Maalin in Merca, Somalia, the last natural case.
• 1978, 11 September: Janet Parker dies in Birmingham after a laboratory-related infection.
• 1979, December: The Global Commission certifies that smallpox has been eradicated.
• 1980, 8 May: The World Health Assembly declares the world free of smallpox.

Legacy

The end of smallpox saved millions of lives and large sums of money that had been spent on vaccination and quarantine. It also left a lasting model for global health. The surveillance methods it pioneered informed later campaigns against polio and Guinea worm disease, and many of the field workers went on to lead public health programmes around the world.

Eradication also raised new questions. Since routine vaccination ended, most people born after the 1970s have no immunity, so the remaining virus stocks and the risk of deliberate misuse have become matters of biosecurity. The World Health Assembly has debated destroying the stocks many times without reaching a final decision.

Why it matters

Smallpox killed hundreds of millions of people over the centuries, yet it was ended within a single generation. Its eradication proved that a disease could be removed from the planet through science, careful organisation and cooperation between rivals, and it remains the benchmark for every global health campaign since.