From the first scary headline on The Drudge Report about the mysterious microbial army massing in Mexico, Americans weren't just warned about the dangers of the H1N1 flu. We were warned about the dangers of panic. "Will Swine Flu Panic Spread Beyond Mexico?" asked Time. "Swine flu panic has hit New York," announced Bild. The Guardian published an online timeline headlined "Swine flu: panic spreads worldwide." A CNN story on emergency room visits by the "worried well"—people who mistake their everyday symptoms for the flu—quoted a doctor declaring, "I haven't seen such a panic among communities perhaps ever."

Midway through May, the disease looks less threatening than it did a month ago. But it's the Black Death compared to the popular panic we were promised, a mental epidemic that set off alarms throughout the media yet never managed to manifest itself on the ground. It's easy to find examples of public anxiety, with every hypochondriac in the country fretting that the cold his kid always catches this time of year was actually the killer flu. But panic? Where's the evidence of that?

The Time story offers thin gruel. It tells us that many Mexicans donned facemasks, as recommended by their government; that stores quickly sold out of masks and vitamin supplements; that schools in Mexico City shut down; that some people left the city and others stayed put. In other words, it tells us that ordinary Mexicans were taking ordinary precautions. The Bild report merely informs us that a few schools in New York had closed and that many children displaying flu-like symptoms were sent home. The Guardian timeline includes a series of links to Mexican photographs that allegedly "capture the sense of panic everywhere." Click through, and you'll see pictures of people calmly going about their business while wearing masks. My favorite photo features a woman on a subway reading a newspaper, a vaguely bored look in her eyes. If this is panic, we need a new word for chaotic stampedes.

Even the CNN story, which at least involves exaggerated worries and a potentially destructive diversion of resources, stops well short of describing a public panic. We learn that the number of patients at the emergency department at Chicago Children's Memorial Hospital more than doubled after the flu hit the news; we learn that some hospitals in California set up triage tents to separate the sick from the merely anxious. We learn nothing about people storming ERs, fighting each other for dwindling medical supplies, or acting in anything other than an orderly way.

"People are sharing information, they're seeking out information, they're asking questions about whether or not they have the symptoms," says Jeannette Sutton, a researcher at the Natural Hazards Center at the University of Colorado at Boulder. "Those are not incidents of panic or hysteria. That's rational thinking, where people are asking questions and trying to make decisions based on the information they have available to them."

When I distinguish anxiety from panic, I'm not just splitting hairs. The fear of panic—actual panic—has shaped public policy in unfortunate ways. During a disaster, it's not uncommon for officials to hold useful information close to their vests because they don't want to "spread panic," even though nine decades of research have established that the public almost always remains calm in such a crisis. "Most scholars seem to agree that whatever 'panic' might mean, the phenomena are statistically quite rare, usually involve only a handful of persons, and are of short duration," writes E.L. Quarantelli, one of the pioneers of disaster research, in the International Encyclopedia of the Social and Behavioral Sciences. "Some researchers have observed that it is very difficult to find clear-cut cases of actual panic in natural and technological disasters (and that they are also extremely rare in the other arena in which they supposedly occur, that is among soldiers in battles during wars). But the term continues to be widely used and persists despite the lack of empirical evidence that it happens on any scale; it also continues...to be the staple of disaster movies and novels."

Now imagine if those officials instead argued that they should hold back important information because they don't want to "spread anxiety." Their position would sound absurd. Nothing fans anxieties like a dearth of solid information, and nothing resolves anxiety like concrete data.

That isn't the only way the fear of panic can influence public policy. The flu crisis has set off a flurry of stories about Twitter's alleged role in spreading hysteria. Entertainment Weekly even got worked up about the fact that twitterers were linking to an obvious parody that described the perils of "zombie swine flu." The writer did not quote a single tweeter who believed the yarn, and he acknowledged at the end that "most users seem to get the fact that the story is a joke." But then he quickly added that Twitter, because it is "so unpoliced," is "the ideal forum for a potential War of the Worlds-like event." (Never mind that, contrary to popular legend, the original War of the Worlds event didn't set off a mass panic either.) Writing on Foreign Policy's influential website, Evgeny Morozov of the Open Society Institute fretted that "having millions of people wrap up all their fears into 140 characters and blurt them out in the public might have some dangerous consequences, networked panic being one of them." He illustrated this by listing a bunch of anxious or rumor-mongering tweets from different users' feeds, without any attempt to see how the comments were being received or in what ways they were or weren't influencing people's behavior. That accomplished, he then warned us that "the next generation of cyber-terrorists" will surely "take advantage of the escalating fears over the next epidemic and pollute the networked public sphere with scares that would essentially paralyze the global economy."

If I were prone to confusing panic with anxiety, I would accuse Mr. Morozov of panicking. You have to hope his line of thought doesn't catch on in Washington. The last thing we need is a horde of hysterical congressmen stampeding to pass a bill that treats Twitter as a national security threat.

It's not as though there haven't been any destructive overreactions to the H1N1 flu. It's just that they've come from officials, not the general public. The government of Egypt certainly overreacted when it ordered the slaughter of every pig in the country, against the advice of approximately 100 percent of the world's public health experts. Russian and Chinese authorities overreacted when they rushed to restrict meat imports, even though it was already clear that there was little danger of getting infected by eating pork. The zookeepers in Kabul overreacted when they quarantined Afghanistan's only pig.

Of the stories I've seen that insisted on conjoining the phrase "swine flu" with the word "panic," the most illuminating is a series of articles by The Guardian's most consistently interesting columnist, Simon Jenkins. While he's prone to the same exaggerated concerns about public hysteria, almost every example of panic that Jenkins presents is actually a case of scare-mongering, with governments and mass media serving as the culprits. "Professional expertise is now overwhelmed by professional log-rolling," he argues. "Risk aversion has trounced risk judgment." His argument brings to mind an idea advanced by the Rutgers sociologists Lee Clarke and Caron Chess, writing this past December in Social Forces, that disasters sometimes spark an elite panic. "This is a controversial claim," they note, "at least from the point of view of mainstream disaster research, which has been arguing against the 'panic myth' for so long that using the word 'panic' at all is anathema. And yet there do seem to be examples." Just ask those Egyptian pigs.

But even then "panic" is a metaphor at best, and it isn't always the most useful metaphor. Afghanistan's sequestered swine might owe his fate more to Islam's attitude toward his species than to any transient health scare. And when Egypt's Muslim government destroyed the livelihood of Christian pig farmers, was it reacting blindly to the crisis or was it using the crisis as an excuse to persecute a religious minority? When Russia and China threw up trade barriers, were they acting hysterically or were they simply seizing an opportunity to limit foreign competition? Were the British bureaucrats who aggravated Jenkins acting irrationally, or were they, as he suspected, making a bid for public resources? "An obligation on public officials not to scare people or lead them to needless expense is overridden by the yearning for a higher budget or more profit," he warns. "Health scares enable media-hungry doctors, public health officials and drugs companies to benefit by manipulating fright."

In other words, it might not just be the popular panic that's been mislabeled. If we examine it closely, we may find that the panic of the elites looks a lot like opportunism.

Jesse Walker is managing editor of Reason magazine.