Flu shot delivered under the skin offers better protection for elderly

Elderly people who received a flu shot under the skin instead of into a muscle were better protected against the deadly viruses, according to a study that may help prevent sickness and death in one of the most vulnerable groups.

Researchers at Sanofi Pasteur, the vaccines unit of Paris-based Sanofi-Aventis SA, found people age 60 to 94 given the shot under the skin using a short, thin needle were about 7 percent better protected against flu than those who received Sanofi's Vaxigrip shot in a muscle with a conventional needle.

The study may lead to changes in the way doctors vaccinate the elderly, whose immune systems are less responsive to infections than younger adults, said Melanie Saville, who led the study. Previous research has shown flu vaccines protect as much as 60 percent of elderly people, compared with 90 percent of younger adults, she said.

"What's new with this vaccine is the system," Saville said. "The idea of this is to have something any practitioner can use."

Seasonal flu kills about 36,000 people in the U.S. each year, and causes a further 200,000 to be hospitalized, according to the Centers for Disease Control and Prevention. About 90 percent of deaths and half of hospitalizations are among the aged, the CDC says.

Saville and colleagues used a so-called microinjection device, with a 1.5 millimeter-long needle, to give 2,612 people a shot containing three different flu viruses into the bottom layer of their skin. A further 1,089 people got a conventional jab in an arm muscle.

Almost 7 percent more of those who received the shallower shot had a fourfold increase in infection-fighting antibodies compared with those who received the conventional vaccine, signaling they were protected against flu. Side effects were similar for both groups.

The device, developed by New Jersey-based Becton, Dickinson & Co., will make it easier for doctors to administer intradermal shots, Saville said. Currently they use conventional needles at a narrow angle, a tricky procedure that can easily go wrong. Sanofi is considering using the device for other vaccines, Saville said.

The findings follow previous studies in adults, which showed intradermal vaccines give a similar level of protection to intramuscular shots, using less antigen.