Flu worries highlight more than one public-health quandary.(In Medicine & Health Perspectives this week)

An Institute of Medicine panel hit it right on the nose in its Aug. 2003 report, Vaccines in the 21st Century: Assuring Access and Availability. The number of companies that manufacture vaccines has been dropping for decades and continues to decline, wrote the committee. And "the rate of exit ... raises two chief concerns: The most immediate of these is the lack of backup capacity should a manufacturer experience production problems or other disruptions.... Longer-term concerns include ... the potential for the total loss of a supply of a vaccine product."

The nation's current loss of half its projected influenza-vaccine supply for the 2004-05 flu season points up the timeliness of the analysis. IOM noted troubling recent history for the U.S. vaccine supply overall in the report that focuses mainly on childhood vaccines, which make up by far the greater part of the industry. Over the past 20 years, the nation has experienced two major periods of supply shortages.

In the mid-1980s, severe product-liability concerns prompted numerous producers to leave the U.S. market, and the production of DPT vaccine--which protects against diphtheria, pertussis, and tetanus--was curtailed.

A second period of short supply--which the panel suggested might be a harbinger of troubles yet to come--ran from the fall of 2000 to the summer of 2002. "It is too soon to determine whether the recent shortages were a one-time event or an early sign of a recurring pattern," wrote the panel. But the 2000-2002 shortage was serious. The United States experienced nationwide shortages of five childhood vaccines that protect against eight of the 11 diseases against which children are routinely immunized.…