Is a new outbreak inevitable?

Yes, because the first outbreak never really ended. Over the summer, the disease has continued to spread through children’s camps and military bases. Now many colleges and universities are reporting outbreaks among students returning for the fall semester. And in the colder fall and winter months, when people spend more time indoors in close quarters, flu cases always rise dramatically. “The virus is still around and it’s ready to explode,” says flu expert William Schaffner of Vanderbilt University. “We’re potentially looking at a very big mess.”

Is the outbreak global?

Yes. Since scientists first identified the swine flu virus last April, it has spread to more than 100 countries around the world, infecting millions from Chile to China, and it’s moving especially fast through Europe. And there are more than 2,800 documented deaths from the disease, although that number probably understates the case. “We are at the early stages of a global pandemic,” says Dr. Margaret Chan, head of the World Health Organization. It’s the first such flu pandemic in 41 years.

How bad could it get?

The worst-case scenarios are dire. The WHO predicts that up to

2 billion people worldwide could be infected in the next two years. If the history of past flu outbreaks is any guide, several million people could die from the disease—90,000 in the U.S. alone. The disease strikes hardest at those under the age of 25, children with neurological problems, pregnant women, and people with weak lungs or fragile immune systems. But those born before 1957 seem less susceptible to the disease, possibly because they developed immunity to distant relatives of the virus during flu outbreaks in the 1950s.

Why is this bug so hard to stop?

Most people have no immunity to it. Swine flu—or to use its official name, H1N1 influenza—bears little resemblance to the typical seasonal flu viruses that sicken hundreds of thousands of people every year. Those who survive a seasonal flu usually develop antibodies to that virus, which protect them from later outbreaks of flu viruses with a similar molecular structure. But few born after 1957 have encountered anything like the H1N1 virus. “This epidemic will travel faster than usual, because the population is more susceptible,” says Marc Lipsitch of the Harvard School of Public Health.

How sick do people get?

Swine flu’s effects are nasty, but so far have been much milder than truly deadly influenzas of the past. As a result, many health experts predict that the pandemic won’t live up to the worst-case scenarios. Most people experience nothing worse than fever, body aches, a sore throat, a runny nose, and, in about half the cases, stomach distress. “If you get it, you feel like you’ve been hit by a train,” says Dr. Harold Standiford of the University of Maryland. “But in terms of causing serious illness, it has not done that very often.”

Are we prepared for an outbreak?

Not entirely. Hospitals are stockpiling respirators and breathing masks, and many schools have set up hand-sanitizer stations near building entrances and in hallways. Health authorities are encouraging employers to develop flexible sick-leave policies, so that people don’t feel compelled to go to work when they’re ill—a big issue in a country where 48 percent of working people don’t get paid sick days. And public-health officers have drawn up priority lists for distributing the H1N1 vaccine. Hospital workers, emergency responders such as paramedics and firefighters, and pregnant women and young people with underlying health problems will get first crack at the vaccine—when it’s ready.

And when will that be?

It will be months before there’s enough vaccine to distribute to the entire population. Pharmaceutical companies started racing to develop a swine flu vaccine as soon as scientists prepared a genetic map of the virus, but it won’t be available in bulk until mid-October, when about 50 million doses should be ready, with an additional 20 million doses coming every month after that. By then, swine flu infection could be rampant. “I think the virus is beating us to the tape, and it will be the virus itself that will immunize us in the fall,” says Vanderbilt’s Schaffner.

How can we protect ourselves?

With soap, facial tissue, and common sense. Until the vaccine is available, the best advice is to wash your hands often, scrubbing for at least 20 seconds—about the time it takes to sing a verse of “Amazing Grace” at a normal tempo. And when you sneeze, cover your nose and mouth with a tissue—or sneeze into your elbow, not your hands—so that you don’t subsequently spread the virus to everything you touch. People who experience flu symptoms should stay home until their fever has subsided for 24 hours. Even with the strictest precautions, though, people are going to get sick. “Flu, like a hurricane, is a force of nature,” says Eric Toner, a public-health expert at the University of Pittsburgh. “You can’t stop it. All you can do is be prepared to deal with the consequences.”

Why they call it swine flu

Pigs are getting a bad rap. It’s true that the H1N1 virus was first detected in pigs, but the virus found in pigs is not the same strain of H1N1 that’s spreading rapidly through the human population. The H1N1 that affects humans is a new mutation, which combines genetic bits from four different subtypes of the virus. And scientists say that humans are at very little risk of contracting flu from pigs. The risk, in fact, is the other way around—pigs are much more likely to contract swine flu from humans. So don’t blame pigs for your sneezes and aches. Dr. Amy Vincent of the U.S. Agriculture Department has studied swine flu for years, and she says that if you get sick, chances are the virus you caught wasn’t brought to your area by a pig. “The most likely scenario is that it came over in the mammalian species that moves most freely around the world.” That means you, humans.