Why Swine Flu Isn't So Scary

As swine flu continues to spread, concerns are mounting about a serious pandemic. Yet based on history and what we know about the flu virus, the threat is not as bad as it may seem.

Regular (seasonal) influenza, of course, is bad enough. In the U.S. we have more than 200,000 hospitalizations and 30,000 deaths annually associated with infections by influenza viruses. These viruses come in three flavors: two kinds of influenza A (named H1N1 and H3N2, after their surface proteins) and one influenza B.

Influenza viruses change frequently. The surface of the virus varies because of ongoing mutations, which ...