New research suggests that giving flu vaccine in a novel way can stretch doses and protect more people, but it didn’t work as well in those over 60 and is too experimental to be used to ease this year’s shortage, experts say.

Scientists tested giving smaller doses of vaccine into the skin instead of full doses given as traditional shots into a muscle. Young people had comparable immune system responses but older people, who are most at risk of dying from flu, did not.

Just measuring response alone doesn’t prove effectiveness or justify changing recommendations for this flu season, said Dr. Myron Levin of the University of Colorado School of Medicine, who is chairman of the government’s vaccine advisory panel.

“What nobody knows is whether or not they’re going to be just as protective,” said Levin, who had no role in the two new pilot studies.

Results were published online Wednesday and will appear in the New England Journal of Medicine’s Nov. 25 edition.

The skin method is used for tuberculosis tests but isn’t licensed for giving flu or any other vaccine. Because of the severe flu shot shortage this year, some doctors may opt to use it anyway on some people, such as health care and day care workers, said Dr. Robert Belshe of St. Louis University, who led one of the studies.

His team gave full doses of Aventis Pasteur flu shots to 119 people and 40 percent doses of an experimental GlaxoSmithKline vaccine into the skin of 119 others. The vaccine used in the research contained strains from the 2001-2002 season.

Antibody responses were similar in people ages 18 to 60, but were 75 percent lower in older study participants, Belshe said.

The new findings “are very exciting but they are still very early” and need to be tested in larger studies that include more older people and those with other health problems, said Dr. Mitchell Cohen, director of the Centers for Disease Control and Prevention’s Coordinating Center for Infectious Disease.