WASHINGTON – One day your annual flu shot could come in the mail.

At least that’s the hope of researchers developing a new method of vaccine delivery that people could even use at home: a patch with microneedles.

Microneedles?

That’s right, needles so small you don’t even feel them. Attached to a patch like a Band-Aid, the little needles barely penetrate the skin before they dissolve and release their vaccine.

Researchers led by Mark Prausnitz of Georgia Institute of Technology reported their research on microneedles in Sunday’s edition of Nature Medicine.

The business side of the patch feels like fine sandpaper, he said. In tests of microneedles without vaccine, people rated the discomfort at one-tenth to one-twentieth that of getting a standard injection, he said. Nearly everyone said it was painless.

Some medications are already delivered by patches, such as nicotine patches for people trying to quit smoking. That’s simply absorbed through the skin. But attempts to develop patches with the flu vaccine absorbed through the skin have not been successful so far.

In the Georgia Tech work, the vaccine is still injected. But the needles are so small that they don’t hurt and it doesn’t take any special training to use this kind of patch.

So two problems are solved right away — fear of needles, and disposal of leftover hypodermic needles.

“The goal has been a means to administer the vaccine that is patient friendly,” Mark R. Prausnitz of Georgia Tech said in a telephone interview.

That means “not only not hurting or looking scary, but that patients could self-administer,” he said, and people would be more likely to get the flu vaccine.