By Karen Garloch - Charlotte Observer, May 4, 2009

About 36,000 people die in the United States each year from complications of seasonal influenza. So why should we be worried about the swine flu, which has killed far fewer people?

Several people have asked me a version of this question in the past week.

Here's what I say:

No one has said the H1N1 swine flu that emerged in Mexico will be more dangerous than the seasonal flu. But it's impossible to predict how serious this outbreak will become.

The concern is that this is a new, never-before-seen virus. That means no one has any natural immunity as we have to many other viruses that circulate year after year.

Some scientists are saying the new virus appears milder than first thought, but that should be of little comfort. The first wave of the

1918-19 Spanish flu pandemic, the worst in history, was mild too.

"It started as a minor wave in the spring and came back with a fury in the fall," said N.C. health director Dr. Jeffrey Engel. "Whether this one will act the same is unknown."

Another concern is that the new swine flu virus has struck otherwise healthy young adults in Mexico. The same thing happened with the Spanish flu, and that's a departure from seasonal flu, which typically affects the very young and the very old.

Because there is so much unknown, there is fear.

Several years ago, shortly after the epidemic of SARS, a respiratory syndrome that surfaced in China, I heard a talk by David Ropeik, director of risk communication at the Harvard Center for Risk Analysis.

"Our brains are built to fear first and think second," he said. "When it's new, it's scarier."

And I'll admit this – just reporting the news can appear to be stirring up panic.

Last week, the Associated Press quoted a man who lives near Newberry Academy, the S.C. school where students became ill with swine flu after returning from a trip to Cancun. Neighbor John Bodie said: "I think the news likes to build it up because they can use that word ‘pandemic.'"

So, temper that fear with these facts.

Remember that pandemic just means we have a new flu virus infecting people around the world at the same time. The word pandemic does not refer to the seriousness of the illness. It can be mild or severe. (An epidemic is an infection that is widespread in a population, but not worldwide and not necessarily involving a new virus.) You hear a lot about the Spanish flu that infected about 25 percent of the world's population and caused 20 million to 50 million deaths.

But you might not remember that our last flu pandemic in 1968

The SARS outbreak, which raised alarm around the world, never reached pandemic status. That's partly because the virus wasn't as easily transmissible as flu, but also because of aggressive, effective public health measures, such as early identification and isolation of sick people and quarantine of those who came into contact with infected people.

Another public health tool is called "social distancing," or keeping people away from one another. That's why officials in South Carolina closed the Newberry Academy last week. We should expect more school closings if signs of swine flu show up in students, and we should support authorities for taking action early.

Some public health officials believe any new pandemic will be more manageable because of these modern public health measures and because we now have effective drugs

In the meantime, what should we do?

Wash your hands often. Cover coughs and sneezes with a tissue or the elbow of your sleeve. Stay home if you're sick. Avoid crowds.

You can wear a mask, but there hasn't been enough research to show whether masks are protective for most healthy people. Right now, federal health officials recommend them for health-care workers and emergency responders who deal with lots of illness.

Masks are also recommended for the sick people themselves, especially if they're sitting in a crowded doctor's waiting room, to prevent from spreading the virus to others.

If you have serious symptoms, don't be surprised if someone asks you to put on a mask.