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In February 1976, an outbreak of swine flu struck Fort Dix Army base in New Jersey, killing a 19-year-old private and infecting hundreds of soldiers. Concerned that the U.S. was on the verge of a devastating epidemic, President Gerald Ford ordered a nationwide vaccination program at a cost of $135 million (some $500 million in today's money). Within weeks, reports surfaced of people developing Guillain-Barré syndrome, a paralyzing nerve disease that can be caused by the vaccine. By April, more than 30 people had died of the condition. Facing protests, federal officials abruptly canceled the program on Dec. 16. The epidemic failed to materialize.

Medical historians and epidemiologists say there are many differences between the relatively benign 1976 outbreak and the current strain of swine flu that is spreading across the globe. But they also say the decisions made in the wake of the '76 outbreak — and the public's response to them — provide a cautionary tale for public health officials, who may soon have to consider whether to institute draconian measures to combat the disease. (See pictures of the swine flu outbreak in Mexico.)

"I think 1976 provides an example of how not to handle a flu outbreak, but what's interesting is that it made a good deal of sense at the time," says Hugh Pennington, an emeritus professor of virology at Britain's University of Aberdeen. Pennington points out that conventional wisdom in 1976 held that the 1918 flu pandemic — which started among soldiers and eventually killed as many as 40 million — was the result of swine flu (scientists now know it was in fact a strain of bird flu). Despite modern advances in microbiology, today's health officials still make decisions in a "cloud of uncertainty," Pennington says. "At the moment, our understanding of the current outbreak is similarly limited. For example, we don't yet understand why people are dying in Mexico but not elsewhere." (See pictures of bird flu.)

In a quickly evolving situation, deciding what public health orders to make becomes as much an art as a science, and can often stir debate. On Monday, for example, health officials in Europe advised citizens to cancel all nonessential trips to Mexico and the U.S. The U.S. Centers for Disease Control and Prevention (CDC) said that advisory was too severe. Such decisions, difficult enough to make on purely medical grounds, become even more complicated when they involve politics. In 1976, President Ford's vaccine program came during an election cycle, and some historians believe he was swayed as much by a desire to display strong leadership as by the advice of health experts. (Read "Swine Flu: 5 Things You Need to Know About the Outbreak.")

Howard Markel, director of the Center for the History of Medicine at the University of Michigan and a historical consultant to the CDC on flu pandemics, says the most vexing decision facing health officials is when to institute mass vaccination programs. Vaccines carry risks of complications, leading to agonizing ethical dilemmas. In 1976, Ford offered indemnity to the vaccine manufacturers. But according to reports, President George W. Bush decided in 2002 not to administer a nationwide smallpox vaccination program — despite Vice President Dick Cheney's belief that doing so was a prudent counterterrorism step — because it could have resulted in dozens of deaths (the smallpox vaccine kills between 1 and 2 people per million people inoculated).

Markel says the political climate in the U.S. is much less combustible today than in the post-Watergate era, when Ford faced a skeptical public. Even so, he says, citizens still need to trust that the government is working for the greater good. He says, "The good news is that our surveillance, methodology and public health professionals have never been better. But we are human and mistakes may be made — as happened with the 1976 swine flu affair — and we may jump the gun in the hope of preserving life. The current outbreak is a situation in flux. The American public has to be forgiving and patient and do [their] part too."

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Read a brief history of the flu vaccine.

• Eben Harrell
• The last major U.S. outbreak of swine flu shows how our response to a crisis can have as big an effect as the crisis itself