The acting head of the Centers for Disease Control said Monday that people can best protect themselves against the swine flu threat by taking precautions they were taught as kids, like frequently washing their hands.

Asked what individual steps should be taken, Richard Besser replied: "The things that we learned when we were little, covering a cough ... staying home when you have a fever, frequent hand-washing. If people do these things, it will decrease the spread in our communities."

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Besser also said the U.S. government is being "extremely aggressive" in the steps it has taken, or is considering, to protect the American public. He said he didn't think he would personally recommend traveling to parts of Mexico where the new virus has taken hold, but noted that no decision has been made on a possible travel ban.

Besser said he was not reassured by the fact that so far in the U.S., no one has died from the disease.

"From what we understand in Mexico, I think people need to be ready for the idea that we could see more severe cases in this country and possibly deaths," Besser said. "That's something people have to be ready for and we're looking for that. So far, thankfully, we haven't seen that. But we're very concerned and that's why we're taking very aggressive measures."

Besser said there can be no one-size-fits-all approach when the severity of the problem varies from area to area. "You cannot see an outbreak occur at the same level in all places," he said.

He also said the government has worked hard to have the necessary medications in place in such a scenario and already has begun distributing them to states.

Asked in one interview why the United States was not issuing travel bans and quarantining passengers at airports, as some countries have done, Besser said: "We are being extremely aggressive in our approach to this outbreak and each day we're evaluating what we're undertaking and we'll make additional measures as necessary. What you're going to see in an outbreak like this is different things taking place in different parts of the country based on what's going on there."

He said that beginning Monday, screening for the illness would being at U.S. borders.

"What we're going to be doing at the borders, and that will be taking place starting today, is doing passive screening, asking people about fever and illness, looking for people who are ill and handing out cards that let people know what's going on in Mexico and what's going on here so people can take action to protect and prepare," Besser said.

The CDC was posting guidelines on its Web site Monday for health departments and members of the public to decide what to do in the event of illness.

Besser appeared on NBC's "Today" show, CBS's "The Early Show," and ABC's "Good Morning America."