D.A. Henderson

Henderson's WHO program used a strategy called surveillance and containment, in which field teams actively searched for smallpox cases through rewards for reporting and then rapidly vaccinated everyone in the surrounding area to create a ring of immunity. This targeted approach proved far more effective than attempting mass vaccination of entire populations in endemic countries.

The last naturally occurring case of smallpox (variola minor) was identified in Somalia in 1977, in a hospital cook named Ali Maow Maalin. After two years of further surveillance with no new cases, the WHO certified smallpox eradicated in December 1979, and the World Health Assembly officially declared eradication in 1980.

Henderson served as dean of the Johns Hopkins School of Hygiene and Public Health (now the Bloomberg School of Public Health) from 1977 to 1990. He later played a key role in U.S. bioterrorism preparedness, serving as the first director of the Office of Public Health Emergency Preparedness after the 2001 anthrax attacks.

Smallpox is estimated to have killed hundreds of millions of people in the 20th century alone, with a case fatality rate of approximately 30% for the variola major strain. It was one of the most devastating diseases in human history, affecting populations on every inhabited continent for thousands of years before eradication.