“People in general do not believe that influenza is a serious disease,” Palese says in his sixteenth-floor office at Mount Sinai, which overlooks the East River. “But 30,000 people die of seasonal flu each year” in the U.S. As he speaks, Palese is balancing a model of the influenza virus—round like a baseball, with knobby blue and pink projections—in his right hand. The nubs represent two proteins on the surface of the virus, blue for hemagglutinin (the H in H1N1) and pink for neuraminidase (the N). Influenza viruses keep changing this top coat. Small year-to-year mutations produce seasonal-flu strains, and those tiny changes throw off our immune system enough to require new flu vaccines each year. The big, whole-cloth makeovers, like in 1957 and 1968, occur when the subtype changes (a switch, for example, from H1 to H3); these new strains produce pandemics, because nobody’s immune system recognizes the new coat.
Flu viruses are very sensitive to temperature and humidity, which is why a typical flu season around here doesn’t usually begin until December. The new H1N1 apparently didn’t get that handbook, because it circulated widely during the summer in the U.S., particularly in sleepaway camps. Palese has a remarkable contraption in his lab—a closed cabinet with four internal shelves, each accommodating two side-by-side guinea-pig cages. He can adjust the temperature and humidity inside the cabinet, testing the conditions by which various strains of flu are most easily transmitted. The new H1N1 strain turned out to be exceedingly catchy. As Dr. Bonnie Arquilla, chief of disaster planning at Kings County Hospital Center in Brooklyn, says, “If you’re exposed to it, chances are you’re going to get it.”
The histories of two previous swine-flu pandemics, one lethal and one imaginary, haunted officials. In the spring of 1918, an H1N1 swine influenza caused mostly minor illness; it came back in the fall, and by the time it had finished its worldwide business, more than 50 million people were dead. Historian Alfred Crosby estimates that New York City suffered as many as 24,000 deaths, and some of the public-health advice and images back then eerily echo today: Sanitation workers wore masks, and patrons at movie theaters were encouraged to cover their mouths when they coughed. In the winter of 1976, four soldiers at Fort Dix, in New Jersey, were hospitalized with another novel H1N1 strain of swine flu, and one died; in the frenzied preparation for an expected pandemic, the government rushed a vaccine into production and more than 40 million Americans received shots against a strain that never reappeared again. After only two months, the vaccination campaign was halted out of fears that more people may have died of suspected side effects from the vaccine than of swine flu itself.
“If you’re exposed to it, chances are you’re going to get it,” says the chief of disaster planning at Kings County Hospital.
The strain of H1N1 that showed up this spring had a different personality that puzzled public-health experts. It appeared similar to the 1918 strain, but its off-season, warm-weather surges were unusual. Perhaps the biggest surprise was that elderly people, usually the most vulnerable to flu, seemed almost untouched by the spring outbreak—“a real head-scratcher,” Don Weiss said during the summer. Children between the ages of 5 and 17, by contrast, seemed especially susceptible.
In fact, Dr. Robert G. Webster, an influenza expert at St. Jude Children’s Research Hospital in Memphis, points out that “young people seem to be driving” the outbreaks, which made the start of the school year a “red flag” time. “It’s a fit virus,” he says. And the key biological wild card is whether it could mutate into something more lethal. “It wouldn’t take much to make this a nasty bastard,” Webster adds.
During the summer, New York City planners and others ran various exercises in dread. One of the scariest potboilers on the summer reading list was the 68-page report that the President’s Council of Advisors on Science and Technology (PCAST) released on August 24, which painted some surprisingly grim possibilities for the fall. One “plausible scenario”—immediately qualified as “not a prediction”—suggested that a fall outbreak of swine flu could produce up to 90,000 deaths nationwide with up to 300,000 hospitalizations, straining the country’s medical infrastructure. It’s an admittedly crude exercise to interpolate the predictions of this “plausible” national scenario to New York City’s 8.4 million residents—about 10 percent of us got involuntarily vaccinated against H1N1 in the spring by actually getting it; on the other hand, we are also exceptionally rich in flu-breeding venues, like the subway—but the numbers convey the gravity of these “what if” exercises.
PCAST’s scenario suggests, for example, that 30 to 50 percent of the U.S. population could become infected; in New York, that translates to between 2.5 and 4.2 million people. According to the same scenario, the report suggests that between 1.2 million and 2.5 million people would be sick enough to need medical care, between 25,000 and 50,000 would require hospitalization, and anywhere from 4,200 to 8,400 people would require treatment in ICU units. (These numbers almost certainly favor the high end; however, scientists who worked on the PCAST models were not available for comment. They are fairly consistent with the figures New York City came up with in 2006 when it undertook a planning scenario for a 1918-like virus.)