In Camden, New Jersey, seniors began lining up at 5 a.m. on an October morning, hoping to snag a flu shot before the supply was depleted. One 72-year-old man, who had suffered seven heart attacks, begged for a shot. He was desperate for the vaccine, he said. He had to care for his three sisters.

Amid all of the October surprises this presidential election year, the loss of half of the nation's flu vaccine supply might have been the biggest. Doses that last year went for free at public health clinics, or perhaps for $20 in walk-in pharmacy clinics, were fetching $800 in the black market. Thieves struck locked refrigerators in doctors' offices, and the search for shots became a new adventure vacation to Canada or Europe.

John Kerry made it a big issue in his campaign, and it quickly became entangled in everything from the Bush administration's plans for Social Security reform to Kerry's charges that Bush had mismanaged health policy. But now that the political furor has receded, what's clearest is the existence of a much larger and more worrisome problem than missing vaccine: the chronically poor condition of the nation's public health system.

We've had disturbing hints of this problem before. The very real 2001 anthrax attacks, and the thousands of false alarms they generated, overwhelmed local officials. First responders were swamped with false alarms that turned out to be food spills in parking lots, and too often, the first responders did not include any trained public health workers who knew how to assess the risks. Local elected officials painfully discovered the costs of decades of underinvestment in public health. One said that finding his closest authorities on smallpox might soon mean visiting nursing homes, because hardly anyone younger than retirement age knew anything about the problem.

More hints of the quiet crisis in public health emerged in last year's flu scare. In the early stages of the flu season, at least five children died in Colorado. The chief deputy coroner in Adams County, Mark Chavez, was quoted as saying that "we have never had a string of deaths like this." Local public health departments first could not get enough people immunized and then were powerless against the quick and sometimes fatal spread of illness.

Then this year's vaccine shortage exploded into the election campaign. Local public health workers complained that they had no warning that trouble was brewing. When half of the expected vaccine supply suddenly became unavailable, they complained further that they were getting no guidance from the federal government about what help they could expect or what they were supposed to do.

For their part, federal officials were stunned by the action of British regulators, who closed the plant in Liverpool, England, on which the United States depended for half its vaccine. Local public health agencies, such as the one in Camden, found themselves caught in a revealing crossfire of globalization and multinational regulation: an American company whose British plant was shut down because of contaminated vaccine, a European plant producing half the vaccine in the United States that couldn't take up the slack, charges of inadequate coordination between the American and British regulators, and poor coordination between federal experts and front-line local government officials.

All of these problems are related. They reflect profound weaknesses in America's public health system--in general. And the implications are growing. If another event like the 2001 anthrax attack occurs, local public health officials will once again be called to the fore. In many communities, the system is better than it was before September 11, but improving public health has been vastly overshadowed by the focus on other first responders and the efforts to strengthen aviation security.

The spread of "bird flu" through Asia has provided strong signals that there's little time to waste. November's "bird flu" summit in Geneva, sponsored by the World Health Organization, focused on the risk of a global pandemic that may be inevitable. In fact, Baylor University physician Wendy Keitel said that the vaccine problems with which American public health officials were wrestling were but a "dress rehearsal" for the problems of rationing and response that such an outbreak would cause.

If--perhaps when--such an illness jumps from Asia to the United States, the implications for local public health would be huge. How much vaccine there is--and how many tough decisions local officials would have to make about who gets it--could well be shaped by the actions of foreign manufacturers, the foreign governments that regulate them, and the patchwork system of American public health management. As this year's vaccine problems show, an effective solution to those problems is a long way off.

We've poured billions into improving airline security to reduce the risks of a repeat of the September 11 attacks. But we've neglected the health protection we need to defend us from the certainty of future problems, of which this year's flu vaccine shortage may have been only a hint.