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The Death of a Disease

By D. A. Henderson, MD, MPH

Geneva, Switzerland, May 8, 1980 - The 33rd World Health Assembly declares solemnly that the world and all its peoples have won freedom from smallpox...a most devastating disease...since earliest time. In so doing, it demonstrates how nations working together in a common cause may further human progress."

In May of this year, the World Health Assembly celebrates the 30th anniversary of its historic declaration of global freedom from the ravages of smallpox, the most virulent of all pestilential diseases.

The planned campaign to achieve eradication began in January 1967. That year, 43 countries experienced more than 10 million cases and 2 million deaths. All countries feared the disease and continued long-standing smallpox vaccination programs whether or not they had cases. International travelers were required to carry certificates showing that they had been recently vaccinated.

However, the decision to undertake the global eradication campaign had not been an easy one. Many doubted its feasibility. No disease had ever been eradicated. A vote was taken in the Assembly to decide whether or not the program should be launched. It was endorsed - by a margin of only two votes. The WHO budget provided an allocation of $2.4 million - not enough even to buy the vaccine required each year. A 10-year target called for the last case to occur by December 1976. The program didn't quite succeed - it missed the target by 9 months and 26 days.

The strategy was simple, consisting of only two components. First was to protect at least 80 percent of a country's population by vaccination, thereby limiting the spread of disease. Second was to begin a program called "surveillance and containment" - to detect cases at the earliest possible time, to isolate them in their homes, and to vaccinate neighbors and friends in a large circle around the infecting houses. The virus could not survive unless it infected one person after another in a continuing chain of transmission. When the patient's contacts were protected by vaccination or previous illness, the virus was blocked and the chain could be broken.

A first, major hurdle for the program was to obtain sufficient heat-stable vaccine. Large, initial donations by the U.S. and Soviet Union provided a basic supply. However, little of the vaccine produced in developing countries was usable. Emergency meetings were convened of the vaccine producers from the two major donors and experts from Canada, the Netherlands and the U.K Standard manuals were developed and members from the group worked on-site with the deficient laboratories. Within five years, more than 80 percent of the vaccine was being produced in the developing countries and all were meeting standards.

New vaccination techniques were introduced that permitted more rapid and effective vaccinations. Jet injectors that could vaccinate hundreds in an hour were superseded by a newly invented simple two-pronged (bifurcated) needle that required much less vaccine and whose use could be taught in a matter of 15 minutes.

Finding outbreaks quickly was essential for the containment strategy. All health centers and hospitals were asked to provide a report every week; two-person teams responded quickly to confirm the diagnosis, to find other cases and to perform vaccination of the patient's contacts. This approach proved to be so effective in stopping transmission that it was given priority over mass vaccination.

Progress in the program was more rapid than any had anticipated. The first successes were in a block of 20 countries in West Africa whose programs were supported by USAID and experts from CDC. These countries had been among the most heavily infected and logistically difficult. Nevertheless, smallpox was on the verge of elimination within three years.

By the sixth year of the program, smallpox had been eliminated from all countries except Ethiopia and four in South Asia - India, Pakistan, Bangladesh and Nepal. This group of countries proved to be far more difficult than had been expected. In the densely populated Asian countries and in Ethiopia, there was a never-ending array of catastrophes and setbacks that left the staff repeatedly reeling in frustration and fatigue - floods, famine, civil wars, kidnapping of teams, political instability, government suppression of reports, and bureaucratic obstacles of every imaginable type. On several occasions, the ultimate success of the program hovered on the brink of a major, perhaps permanent setback. However, a dedicated, resourceful array of national and international staff persisted and eventually celebrated the occurrence of the last case on Oct. 26, 1977.

An important legacy of the program was the demonstration of the importance of surveillance in working out strategies in disease control. It depended on weekly reports being submitted promptly by all health centers and hospitals and containment teams to be sent. The teams were usually on-site within one to two days and this reinforced the fact that the reporting of cases had actionable meaning. It was an approach that was alien to programs throughout the developing world.

Although smallpox vaccination teams had been in use for many years, it was surprising to discover how effective such teams could be when villagers were properly approached and when the teams were well supervised. In Africa, teams could readily average 500 vaccinations daily per vaccinator. Why not increase the number of vaccines being given? In the developing countries, there were few vaccines then in regular use. Resources were a problem and international agencies focused primarily on a foundering malaria eradication effort. Some yellow fever vaccine was administered in heavily endemic areas; BCG vaccine was provided to a few countries by UNICEF; but basic vaccines such as DPT, measles and polio were little used.

In 1970, we convened an international WHO meeting to develop recommendations for a program on immunization that would extend beyond smallpox vaccination - that it include DPT, measles, polio and BCG vaccines as routine immunizations for all children - an Expanded Program on Immunization. This was endorsed by the World Health Assembly in 1974. Eventually, UNICEF took this on as a priority and Rotary International volunteered to raise millions of dollars for polio vaccine. The goal was to reach 80 percent vaccination coverage for all children throughout the world by 1990. And so momentum was established for ever larger-scale programs to make products for better health conveniently available to villagers. These eventually have included many other vaccines, Vitamin A capsules, bed nets for malaria, and others.

The achievement of smallpox eradication is a landmark. It is a tribute to an international staff that never numbered more than 150 in the field; to national leaders and staff who capably undertook new tasks; and to the World Health Organization that provided the framework within which all countries could constructively work even during days of the Cold War.

It is the behind-the-scenes drama of this victory that I have endeavored to portray in my book, Smallpox: Death of a Disease (Prometheus Books, 2009).

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D.A. Henderson, MD, MPH, led the WHO's Global Smallpox Eradication Campaign. He is currently a distinguished scholar at the Center for Biosecurity and a professor of medicine and public health at the University of Pittsburgh Medical Center. He is also a distinguished professor and the former dean of the Johns Hopkins School of Public Health.