Studies: Flu vaccine's effectiveness in elderly unclear

At 67, Helen Wong hasn't missed her annual flu shot in years. She also hasn't been seriously sick in years. Wong is pretty sure there's a connection, and she'll be sharing that conviction this fall with fellow members of her fitness club at the Glassell Park Senior Center, five miles north of downtown Los Angeles.

When it comes to flu vaccination, there are always doubters, says Wong, a resident of Glassell Park and a regular at its senior center.

But Nov. 1, when the center holds its annual flu immunization clinic, Wong expects that many of her peers will line up for the shot.

"I'm finding confidence growing" in the long-advertised benefits of the vaccine for older people, she says -- that it drives down the odds of catching the flu, of developing complications from the illness such as pneumonia, of dying.

Among medical researchers and health professionals, however, confidence in those benefits has turned in the opposite direction.

After six decades of steadily expanded use among the elderly, flu vaccination for seniors has come under critical scrutiny in several studies. Collectively, they suggest that for those older than 65, flu vaccination may confer fewer benefits than have been widely advertised.

Researchers such as Lone Simonsen of George Washington University say the skepticism is overdue. The medical profession's wariness should have been piqued by a simple but glaring disconnect, says Simonsen, a former epidemiologist for the National Institute of Allergy and Infectious Diseases: The flu vaccination rate among U.S. seniors has risen more than fourfold over 25 years -- to 65 percent in 2007. During the same period, hospitalization for and deaths caused by flu or pneumonia appear to have declined only marginally in the nation's 65-and-over population. It just doesn't add up, she says.

"If I could have it my way, we would start by going back and looking at the basic premise for flu vaccination of seniors," says Simonsen, the author of one of the first studies to question the vaccine's benefits for seniors.

Studies on the effectiveness of flu vaccine in older populations have had a wide range of methodological problems, Simonsen says.

Although their weaknesses are varied, their effect is almost invariably skewed in one direction, she says: The studies have produced a view of vaccination that is "is far too rosy."

Since the late 1950s, when flu vaccine became widely available, a belief in the vaccine's lifesaving benefits for older people has been the cornerstone of the nation's immunization policy. Not surprisingly, then, the studies that cast doubt on those benefits have been met with concern and hostility.

"These studies are acknowledged to be less specific. More specific studies show clear evidence of effectiveness in individuals and subpopulations," says Dr. William Schaffner, chairman of Vanderbilt University Medical School's department of preventive medicine and an executive board member of the Infectious Diseases Society of America.

Schaffner acknowledges that among those older than 70, flu vaccine often produces a weak response. "If we wait for something much better, we are missing the opportunity to provide some protection for people who need it."

The centers for Disease Control and Prevention estimate that flu kills about 36,000 people in the United States annually. For most of the deaths counted as flu fatalities, pneumonia -- a frequent complication of flu -- is listed as the cause.

For those 65 or older, the lesson is clear: A dose of pneumococcal vaccine is a good way to bolster protection against complications of flu. A single dose, says the U.S. Department of Health and Human Services, can protect against 23 types of Streptococcus pneumonia bacteria thought responsible for causing more than 90 percent of pneumonia cases.

The latest of the critical studies, published in the Aug. 2 issue of the Lancet, followed the cases of 3,519 patients older than 65 -- all admitted to the hospital with pneumonia either during or just before the flu seasons of 2000-2002. After separating those who had been vaccinated against flu from those who had not, and accounting for other health factors, the study found that the group that had been immunized against flu appeared no less likely to develop pneumonia requiring hospitalization than those who had not.

On the heels of that study came a second, conducted by Canadian researchers, that looked at the death rates of elderly hospitalized patients with pneumonia. About 8 percent of the patients vaccinated against flu died, compared with 15 percent of the non-vaccinated patients.

But when researchers paired patients of similar age and health status and then looked at their comparative likelihood of dying, they found that age and frailty -- not flu vaccination -- seemed to account for which patients were most likely to die of pneumonia during flu season. At the same time, they noted, seniors who were younger, more active and generally in better health were more likely to be vaccinated.

The study's lead author, Dean T. Eurich of the University of Alberta School of Public Health, concluded that past studies likely attributed to vaccination the benefits that actually come from what he called the "healthy user effect": Seniors who get vaccinated against flu tend to be younger, healthier, more active and better able to take care of themselves. For those reasons -- not flu immunization -- they are less likely to succumb to pneumonia, Eurich said.

Both Simonsen and Schaffner agree that the current dispute among experts should not sway seniors inclined to get the shot from doing so. With a vaccine that is safe and easy to get -- this year, at least -- some protection against flu is better than none at all, they say.

(Many people don't seem to know that a dose of pneumococcal would benefit them as well.) "No one is saying don't vaccinate seniors. It would be imprudent to do that," Simonsen says. Indeed, several studies have pointed to the need for community groups, hospitals and nursing homes to step up their efforts to vaccinate frail and elderly patients at highest risk of dying if they contract flu.

But clinging to inflated measures of effectiveness discourages public health officials from exploring and encouraging better vaccines, more effective ways of administering them, and improved vaccination policies to protect the elderly, Simonsen says.

The decision to recommend the widespread vaccination of schoolchildren is one way to protect seniors from flu. At the same time, the poor response many older patients have to the vaccine -- a function of their immune systems' decline -- suggests other improvements that could be made.

New vaccines, higher doses of existing vaccines and vaccine formulations with additives designed to jump-start the immune system -- have been tested and have shown promise in boosting seniors' immune response, Simonsen says. But they are moving slowly toward adoption.

"We're not limited by technology. We're limited by studies that say everything is fine," Simonsen says. "If the system is broken, we can fix it. But if we don't know it's broken, we can't."