Flu shots provide only modest protection for people over age 65, and there's little evidence that giving flu shots to health workers protects their elderly patients from the flu, two new studies find.

National and international health organizations currently recommend that people over age 65 get a yearly flu shot.

Italian researchers at the department of public health in Asti reviewed 71 previous studies. They found that flu shots prevented 45 percent of flu-like illnesses, hospital admissions and flu-related deaths among people living in nursing homes and long-term care facilities.

The review also found that flu shots prevented 25 percent of these outcomes in elderly people who still live in the community.

Current recommendations that elderly people get an annual flu shot are based, in part, on statistics that show that people who receive a flu shot are among those least likely to die from any cause in a given year.

However, the people who are most likely to get a flu shot are also those most likely to have higher incomes and better health care, the review authors noted. This may mean that the apparent benefits of flu shots may simply reflect the fact that people who get the shots tend to have better health care to begin with.

The authors said their findings do suggest that flu shots may be effective in protecting residents of nursing homes and other institutions.

The second review, this time by a Canadian team at the University of Calgary, found some evidence that giving flu shots to staff at nursing homes can reduce patient pneumonia deaths but doesn't decrease cases of flu or lower respiratory tract infections among the patients.

Both reviews are published in the current issue of the journal The Cochrane Library.