An annual flu vaccine decreases by one third the risk of hospitalization due to flu complications, a new study has found.

Getting a flu shot every year could cut the risk of dying from flu in half for people over 65, according to the study conducted by researchers at Northwestern Memorial Hospital in Chicago.

The researchers studied more than 400,000 people aged over 65 who had been vaccinated and 300,000 seniors who hadn't. All the study participants lived on their own, not in nursing homes or other long-term care facilities.

The findings showed that those who received a vaccine were 27 percent less likely to be hospitalized due to flu complications, compared to the unvaccinated.

The death rate was 48 percent lower for those who received the annual flu shot, according to the study published in the January issue of New England Journal of Medicine.

"Most people feel that influenza is a mild disease and one that doesn't cause people to become very ill," said infectious disease specialist Dr. Michael Ison who took part in the study. "But it can cause serious complications, and the majority of hospitalizations and illness is in people greater than 65."

Every year, between 5 percent and 20 percent of the U.S. population is infected with the flu virus, and flu is responsible for more than 200,000 hospitalizations and about 36,000 deaths every year, according to estimates from the U.S. Centers for Disease Control and Prevention (CDC).

To prevent some of these illnesses and deaths, the CDC recommends that many groups be vaccinated against the flu each year, including pregnant women, children from 6 months to 5 years of age, anyone over age 50 and people with chronic medical conditions.

(Xinhua News Agency January 13, 2009)