LONDON -- New research indicates that flu shots aren't as effective in the elderly as previously thought. But health officials say older people should still get the vaccinations anyway.

An international group of scientists known as the Cochrane Review Group found the vaccine is only about 28 percent effective when given to people over 65. Older people are particularly vulnerable to influenza.

Combining data from 15 studies, the researchers found that in elderly people, flu vaccines were not effective against influenza-like illnesses, influenza, or pneumonia -- but they prevented up to 30 percent of hospitalizations for pneumonia.

The vaccine had more benefits for elderly people in long-term care facilities. Combining data from 29 studies, the researchers found that, in that setting, flu vaccines prevented up to 42 percent of deaths caused by influenza and pneumonia.

The findings, published in this week's issue of The Lancet medical journal, are similar to those of a study done by the U.S. National Institutes of Health that found flu shots for the elderly had not saved lives.

But a researcher at the Centers for Disease Control and Prevention said if he had a loved one in the high risk group, he'd "strongly recommend they get vaccinated."