Preparing for the Next Influenza Pandemic: A Reemerging Infection

If a foreign army invaded the United States and in a few months ravaged the population, killing 22 000 men, women, and children and then leaving, the loss would be overwhelming, and the nation would turn its collective efforts to preventing such a tragedy from occurring again (1). In fact, this inva-sion occurs almost every year in the United States, but the foreign invader is a pestilence: a new strain of influenza virus. And we are not shocked by the tragedy, and we do not make every effort to prevent its recurrence. While "emerging " in-fectious diseases—such as those caused by the Ebola virus in Africa, the hantavirus in the United States, and multidrug-resistant bacteria ev-erywhere—hog the headlines, we need to be re-minded that a "reemerging " infectious disease, influ-enza, takes an even greater toll in lives (2, 3). This awareness should prod us to cope more effectively with the almost annual epidemics of influenza while, at the same time, we begin to plan for the next influenza pandemic. Four influenza pandemics have occurred in the 20th century, and they are a study in contrasts. The 1918 Spanish influenza was the most devastating: It killed 550 000 persons in the United States and 20 million persons worldwide. The 1977 Russian influ-enza had a relatively minor effect and did not in-crease mortality (4). The 1957 Asian influenza and the 1968 Hong Kong influenza had effects in be-tween those of the Spanish and Russian influenzas. The expected 1976 swine influenza pandemic never materialized. These events have been considered at recent meetings held to prepare for the next influ-enza pandemic, which is expected to be the result of a new influenza subtype that can cause worldwide illness on a massive scale, potentially affecting its victims during a short period and creating serious health consequences (5)