A new formulation of an inhalable flu vaccine that can be stored refrigerated instead of frozen won federal approval, its manufacturer said Monday.

The new version of FluMist should allow for expanded use of the vaccine in places like schools, pharmacies and grocery stores, where the requirement that the original version of the vaccine be kept frozen presented difficulties, according to its manufacturer, MedImmune Inc.

The Food and Drug Administration originally approved FluMist in 2003. The nasal spray delivers weakened live viruses to patients.

FluMist is approved for healthy people ages 5 to 49, though the company seeks expanded approval for use in children as young as 1 as long as they don't have a history of wheezing or asthma.

MedImmune said the new formulation should be available in August, in time for the 2007-2008 flu season. The company is based in Gaithersburg, Md.