It seems logical: Why not try to get sick with swine flu now, and get some immunity in case it comes roaring back this fall in a deadlier form? Sort of like those "pox parties" to get your kids exposed to a childhood disease.

Bad idea, flu experts say. It's too risky.

It's true that once your body has encountered a particular virus strain, it is generally better able to fight it off later on. Vaccines work by masquerading as germs, priming the immune system to attack particular bugs.

The current swine flu appears no deadlier than ordinary flu, but scientists worry that it could return in a more lethal form during the regular flu season in fall and winter. That's what happened in the deadly pandemic of 1918, and there's evidence that people who got sick earlier that year had protection when the lethal wave came.

So wouldn't it be a good idea to get sick now?

"I understand the logic (but it) leads you astray," said Dr. William Schaffner, a flu expert at Vanderbilt University.

He said there's no way to predict how bad a case of flu will be in a particular person. Given the risk of life-threatening complications, "this is not something where you want to do a biological experiment," he said.

"You can't control the infection that you're going to get, and you may be the one, or your child may be the one, that gets a severe infection."

What's more, a person who decides to get sick can accidentally pass it along to other, more vulnerable people, even before any symptoms show up, he said.

Dr. Robert Atmar, a flu researcher at the Baylor College of Medicine in Houston, agreed. He said he would "strongly recommend against" purposely trying to catch the new flu.

For one thing, it's not yet clear that swine flu will return in deadlier form this fall. "Why roll the dice when you may not need to?" he asked.

He also said flu medicines should be available to ease symptoms of patients during the winter flu season, and that scientists hope a vaccine will be ready by then.