In epidemics, is fear a good thing?

Since SARS was first reported, the World Health Organization has freely issued travel advisory warnings, and the press has had a field day covering every incremental detail of the unfolding epidemic. At last there’s been a backlash to all the hysteria: In today’s Los Angeles Times, the distinguished virologist David Baltimore, president of Caltech, spoke out against a media-driven epidemic of fear that, among other things, has emptied Chinatowns all over North America. And today’s New York Times Op-Art piece made the point that compared with many other infectious diseases SARS really isn’t a player—especially not in the United States.

In a sense, Baltimore is right on the money. While the human tragedy of lost lives is always great, SARS’s mortality figures alone cannot justify the attention. From December through April, an outbreak of Ebola tore through a remote region of the Congo, eventually infecting 135 people, of whom 123 died—a mortality rate of 91 percent. Yet this outbreak received almost no media coverage. I found out about it only because I was visiting the WHO Web site to read its announcements about, you guessed it, SARS.

But the news frenzy and its ensuing backlash contain a double irony: On the one hand, the level of attention given to SARS seems wildly disproportionate to the scale of the problem itself; on the other hand, had it not been for this exaggerated sense of fear, we might have a truly frightening situation on our hands.

While SARS has made appearances in 27 countries, it has, to date, infected no more than about 5,500 people globally and less than 350 have died. Even if one takes into account the unpredictably insidious nature of an infectious disease, which can be spread between strangers who share nothing more than the same aircraft, these numbers suggest that the mass avoidance of Asian cities by global travelers—and the near-universal wearing of face masks in places like Hong Kong—is an overreaction. Although SARS can be spread by coughing, the relatively large size of the droplets in which the virus is transmitted significantly limits the distance it can travel to infect a healthy person—at least compared to an airborne disease like influenza. Most transmissions have occurred between individuals who have had prolonged close contact, such as health workers caring for infected patients or family members visiting their sick relatives. Few transmissions have been traced to airplanes and none to simply walking down the street. Your chances of visiting Hong Kong without getting infected are close to 100 percent—even if you don’t take special precautions. All of which suggests, as is now being argued, that the economic damage done by the fear of the disease may be far more dangerous than the disease itself.

But this eminently reasonable reasoning fails to account for the evidence that is not at hand: All the fuss may well have contained what could have been a truly panic-worthy epidemic. While we have yet to learn how bad the epidemic will get, it is almost certain that without the WHO’s pre-emptive global alert and the resulting avalanche of news stories about the disease, the situation could have been far worse than it is. Though SARS is not quite as contagious as the flu, it can still be spread through relatively casual contact. If lots of sick people were taking long plane flights or wandering around on the streets for days, the risk of catching it from them might not be negligible. We know that a handful of individuals can spread the disease from one country to 26 others in a matter of weeks (SARS was introduced to Hong Kong, which now has the highest rate of infection, by a single person arriving from mainland China). How much worse would the epidemic be if travelers had not avoided certain cities; if airports had not quarantined symptomatic passengers; and if sick people had not confined themselves (or been confined) to their homes? Almost certainly much worse, in which case we would have had the hysteria and the economic damage, anyway. And we’d also have an epidemic on a scale that was really something to panic about.

All this should lead us to rethink Roosevelt’s famous quip about fearing only fear itself: It appears that fear can be a useful tool for the public good. One reason that HIV managed to spread globally, breaking out of its core population of gay men, prostitutes, and intravenous drug users, was due to a general perception that it couldn’t. AIDS is the problem that it is today because we weren’t scared enough. (And perhaps we still aren’t scared enough. Even as the number of HIV-positive individuals soars past the 30 million mark in Africa, health clinics continue to reuse needles—a practice that has been recognized for over a decade as the single most effective way to spread the virus.)

So, our real concern ought not to be that we are too easily scared, but that we are too easily reassured. China, for example, might have prevented the epidemic from spreading outside the rural area in which it first broke out if its public health authorities had instilled a little more preventive fear in the population. Articles suggesting that fear of the disease and not the disease itself is the real problem may usefully enable us to go about our lives in a more productive fashion; but if they persuade us not to take the next such outbreak of disease as seriously, they will not be doing us a favor in the long term.

But, you may wonder, how much fear is healthy? And faced with a myriad of imaginable threats, which ones should we be most scared of? As terrifying as a 90 percent mortality rate is, there are good reasons that the WHO did not consider the African Ebola outbreak to be of the same magnitude as SARS in China. By nature, Ebola is much harder to transmit than SARS; it also debilitates its victims relatively quickly. As long as local response is swift, the potential for Ebola to spread globally is limited, no matter how devastating an outbreak is. Ebola is literally too deadly for its own good. SARS, by contrast, had “global” written all over it from the very first; it was the WHO’s recognition of this that prompted such an early and aggressive awareness campaign.

In 1918, the Spanish flu caused more than 20 million deaths worldwide and was the most deadly epidemic of all time. In the United States, the disease’s spread was drastically accelerated by large public gatherings celebrating Armistice Day—which were held well after the epidemic was in full swing. Many more Americans—some 675,000—were killed by influenza than by the Great War itself. An early wave of fear about this deadly disease might have averted much of the catastrophe.

This historical lesson has not been lost on the WHO, and the rest of us would do well to pay attention, too. In a world that is growing ever more connected, at an ever faster pace, the distant has become near, and the burdens of others have become our burdens. Under those circumstances, it’s OK to be a little afraid—in fact, our fear may be what saves us.