The global eradication of smallpox, certified in 1979, is one of the greatest public health achievements in history. It marked the end of a disease that in the past had killed 3 million people every year and scarred or blinded millions more. It also commemorated a decade, during the Cold War, when all countries united behind a common humanitarian cause. The United States was the largest donor and provided major logistic and staff support. The Soviet Union was the largest supplier of vaccine.
In 1967, when WHO launched its plan to eradicate smallpox in 10 years, the disease was endemic in 31 countries with a total population of over 1 billion. Most of these countries presented formidable obstacles: teeming cities, poor health care systems, fragile governments, civil unrest, famine, war, and remote areas unmapped and inaccessible by road.
No effective treatment against smallpox was ever developed. Vaccination, supported by surveillance and containment, was the cornerstone of the eradication drive. And—against considerable odds —it worked. When the last natural case occurred in Somalia in 1977, one of history's longest chains of transmission, at least 3000 years old, was broken.
In the immediate posteradication era, the commission responsible for certification of eradication charged WHO with ensuring that smallpox was gone and would have no chance to return. It also recommended that variola virus stocks be destroyed or given to WHO for safekeeping in one of two institutes (JAMA. 2002;287:706).
Smallpox eradication was a triumph for preventive medicine and for the power of international cooperation. The success of this global effort raised the profile of public health in the eyes of politicians and economists as well as in medical and scientific circles. It provided guidance for other WHO-led programs aimed at curbing deaths from diarrheal and respiratory disease. It spawned the Expanded Programme on Immunization and created momentum that has continued to swell, expressed most recently in the creation of the Global Alliance for Vaccines and Immunization. The smallpox threat was consigned to history, a public health problem once and forever solved, that could now be forgotten. Vaccination of civilian populations ceased everywhere.
Following recent events that culminated in the deliberate and malicious use of anthrax to incite terror, the potential threat has returned. Suspicions that smallpox virus may be held somewhere else than the two officially designated institutes have given rise to questions about whether the virus may be deliberately used to cause harm.
Smallpox, with other biological agents that might be deliberately used to cause harm, is once again in the political, public health, and media spotlight. A single confirmed case of smallpox would be an immediate global emergency. Although it spreads slowly, requiring face-to-face contact, it is highly contagious. The incubation period is long: 12–14 days. Immunity has waned and populations are vulnerable. The current vaccine, though highly effective, has rare but serious and potentially fatal complications.
In collaboration with the Centers for Disease Control and Prevention and other partners around the world, WHO has reissued training materials for smallpox recognition, differential diagnosis, vaccination technique, and the management of an outbreak. We have made available archival video films showing how those who contracted this now-extinct disease looked and how containment operations worked. We have conducted a global survey of smallpox vaccine stocks and vaccine seed virus. We have contacted manufacturers who supplied smallpox vaccine during the eradication program to gauge the world's production capacity. We convened meetings of expert advisers to confirm that the search and containment strategy remains valid and to consider the continuing need for research using variola virus to produce safer vaccines and therapeutic drugs. To generally guide national preparedness, in September we issued an updated edition of our guide on the Public Health Response to Biological and Chemical Weapons.
The backbone of preparedness for a bioterrorist attack is a good system of disease surveillance and response designed to deal with known infectious disease risks. The epidemiological and laboratory techniques needed to detect, investigate, and contain a deliberately caused outbreak are the same as those for natural outbreaks. Mechanisms for performing these functions on a global scale are firmly in place.
The infrastructure for detecting and responding to outbreaks, natural or deliberate, is the Global Outbreak Alert and Response Network, a partnership that links more than 100 existing networks and operates within the framework of the International Health Regulations. Together, these networks possess much of the data, expertise, and skill needed to keep the international community alert and ready to respond. The network, which was formalized in April 2000, is supported by a computer-driven tool for real-time gathering of disease intelligence.
Let us hope that the deliberate use of smallpox shall never come to pass. But if it should, there is a system in place, alert and prepared to respond.
