WASHINGTON -- A long-awaited pain-free flu vaccine - one squirted up noses instead of injected into arms - took a tentative step toward the market Tuesday even as government scientists said FluMist is safe enough for only some people to use.

But FluMist is not proved safe for the people who most need a flu vaccine or a pain-free option - toddlers, the elderly and anyone with asthma or other chronic diseases, advisers to the Food and Drug Administration stressed.

Indeed, FluMist initially was created with the hope of giving toddlers a needle-free vaccine, but researchers discovered it seems to increase the risk of asthma attacks in children under age 5.

So in its second attempt at winning FDA approval in two years, the vaccine's maker withdrew its plans to sell FluMist for toddlers, saying it would instead target healthy people aged 5 to 64.

The FDA's advisers threw a monkey wrench into the new plan Tuesday - recommending approval only for those aged 5 to 49. They concluded there's too little evidence that FluMist protects people 50 and over, an age when the immune system begins to wane.

Now the question is whether the FDA, which is not bound by its advisers' recommendations, will let a vaccine with so many restrictions sell. If so, the uncertainties would severely limit how often doctors offer FluMist instead of the flu shots that 70 million Americans get every year.

A big unanswered question: Is FluMist as good as that standard flu shot? After all, FluMist is made of a weakened but live flu virus, while today's flu shots are made of killed virus. Manufacturer MedImmune Inc. hasn't compared the two vaccines.

Flu kills 20,000 Americans each year and hospitalizes 100,000.