Two major developments involving the flu vaccine

PITTSBURGH,None — We’re tracking two major developments involving the flu vaccine.

A new study found flu shots may not work if you're overweight. And supermarket and pharmacy chains are pulling popular needle-free flu shots after an advisory from the FDA.

Let's start with the new study. It found the flu vaccine was less effective in obese patients than it is in those at a healthy weight.

The study was conducted at a clinic at the University of North Carolina-Chapel Hill. Researchers found, if you're obese the flu vaccine may not work as well, and if you get the flu a flu shot may be less effective at reducing the illnesses' severity.

UNC-Chapel Hill researchers don't want to send the wrong message. They still want overweight patients to get an annual flu shot, because it will provide some protection against influenza, even if it’s not as effective.

During the H1N1 pandemic researchers noticed that overweight people were not only more likely to get swine flu. They were more likely to die from it.

The study was just published in the International Journal of Obesity.

The second major development involves needle-free flu shots. On Friday, Giant Eagle pulled needle-free flu shots from its stores after the Food and Drug Administration posted an advisory about them.

Target 11 did a story about needle-free flu shots a few weeks ago. People told us they were less painful than traditional injections. The vaccine is administered in less than a second using a jet-injection device that is similar to an air gun.

The quick blast penetrates the skin sending the vaccine into the muscle, but the FDA announced on Friday that system of delivery is not cleared for the influenza vaccine, just measles, mumps and rubella.

At this point, the FDA says there's not enough evidence to prove the injection device is effective with the influenza vaccine.

Supermarket and pharmacy chains were advertising the needle-free shots as a quick and easy way to get vaccinate.

The FDA and Centers for Disease Control have weighed in on the subject, saying anyone who got a needle-free shot does not need to be revaccinated.

Giant Eagle will still administer flu shots the traditional way.

WPXI