With flu season approaching, is there a better time to add a dose of confusion to the annual public-health plea for the elderly to get vaccinated? A report in the latest issue of Lancet Infectious Diseases is just what the doctor ordered to raise more questions than there are answers.

Every year, about 300,000 Americans are hospitalized with the flu; about 36,000 of those, nearly all elderly, will die of it. And for decades public health officials and doctors have urged older Americans to get a flu shot. The practice has been picked up by other industrialized nations and now is commonplace worldwide. However, according to researchers, while vaccination coverage rose from 15 percent in 1980 to 65 percent today, mortality studies have not shown a corresponding drop in flu-related deaths.

Lone Simonsen of George Washington University and fellow researchers say that while controlled, randomized trials show a benefit from vaccinations in younger adults, “few trials have included elderly people, and especially those aged at least 70 years.” They point out that older immune systems may not react the same way as younger ones do. Even so, they recommend older people continue to get flu shots until definitive data say otherwise.

This lack of scientific evidence for a practice in one of the most scientific of professions is the latest in a series of observations on potentially unneeded costs that make health care so expensive. Recently on these pages, columnist Dr. Erik Steele wrote: “Money is [a] key reason for unnecessary tests and treatments. The majority of patients do not pay for all of their health care, providing them some protection from the financial ramifications of unnecessary tests and treatments.” More, few doctors have a financial incentive not to perform a test or procedure.

Dr. Steele recommends that patients ask doctors whether a test is really necessary before agreeing to undergo it. But real change, whether for the number of flu shots or X-rays or in the widespread use of antibiotics, can come only from the doctors themselves. The rest of us don’t know enough, in a systematic sense, about the value of particular treatment.

In the case of the flu-vaccine question, the doctors themselves must demand more evidence, review the validity of the evidence offered and decide whether for older people some of the limited amount of money the nation spends on health care is best spent on these shots. They could decide to aim the needles elsewhere.