In 1918, a new influenza virus, whose natural home was in birds, infected man. Within months, it adapted to its new host, starting with U.S. soldiers in World War I military camps, and began rapidly spreading from person to person.

This influenza virus killed more people than any other plague in history. In 24 weeks, it killed more people than AIDS has killed in 24 years. The most recent scholarship confirms the earlier judgment of Nobel laureate Macfarlane Burnet that likely 50 million people, and perhaps as many as 100 million, died. The world's population then was only 28% of today's; a comparable death toll today would be 175 million to 325 million.

As a case study, the 1918-1919 influenza epidemic offers many lessons for today about how scientists operate in emergencies, public health measures, distribution of resources, crisis management and the use and abuse of information. But the most important lesson is to take...