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Oct. 3, 2007 -- Giving flu shots to older adults is a highly effective way to prevent influenza and pneumonia-related hospitalizations and death in this highly vulnerable population, a new study shows.
Vaccination was associated with a 27% reduction in the risk of hospitalization for flu or pneumonia and a 48% reduction in the risk of death in members of several of the nation’s largest HMOs followed for up to 10 flu seasons.
The study comes just a week after publication of a research review suggesting that the benefits of vaccinating the elderly against the flu may have been exaggerated.
While there is still debate among the experts about just how effective flu shots are in older populations, there is widespread agreement that elderly people should be vaccinated, vaccine researcher John D. Treanor, MD, tells WebMD.
“Everyone understands it would be great to have a better vaccine, but the one that we have clearly does work and it is very well-tolerated,” he says. “Vaccination is one of the best ways we have to protect older people.”
(Will you get a flu shot this year? Will you encourage your aging parents to get one? Share your thoughts on our Active Aging message board.)
Past studies examining the effectiveness of flu shots in the elderly have generally compared outcomes among people who did and did not get vaccinated by reviewing medical records.
These studies have consistently shown an association between vaccination and reductions in seasonal flu and pneumonia-related hospitalizations and death.
But some have questioned the findings because the studies also show reductions in deaths from other, noninfectious disease-related causes during flu season.
“The conclusion you might draw from this is that influenza is responsible for a significant proportion of all the deaths in the elderly that occur during the winter, and many people feel that is not realistic,” says Treanor, who directs the vaccine and treatment evaluation unit at the University of Rochester Medical Center.
One theory is that healthier elderly people get flu shots more often than sicker and frailer older people. If this is the case, the doubters say, the healthier, vaccinated population would be expected to have fewer hospitalizations and deaths. ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????The
The new study, which appears in the Oct. 4 issue of The New England Journal of Medicine, was designed to address this and other concerns.
Kristin L. Nichol, MD, MPH, and colleagues examined the effect of flu vaccination in up to 10 influenza seasons in older members of three geographically diverse HMOs, including years when there was a good match between the vaccine and the influenza outbreak and years when the match was not as good. Participants were at least 65 years old with an average age of 74.
The vaccinated older people in the various HMOs were more likely to have high-risk medical conditions than those who were not vaccinated. High-risk medical conditions included diabetes, heart disease, lung disease, cancer, and stroke.
Reductions in the risk of flu-related hospitalizations and death were seen over all flu seasons in flu shot recipients, but the effectiveness in reduction of deaths was slightly less in the two years with a poor match between the vaccine and the circulating virus strains.
“You would expect the impact to be somewhat lower in years where there was not a good match, and this is what we saw,” Nichol tells WebMD. “But the good news is that even in the years when protection wasn’t as good as it could have been there was still clinically relevant protection.”
Nichol, who is chief of medicine at the VA Medical Center in Minneapolis, says the new study offers unequivocal evidence in support of vaccinating the elderly against the flu.
“Our study doesn’t say the vaccine is perfect, or that we should not be searching for better vaccines or looking at different strategies for protecting this population,” she says. “What is does say is right now, even as we are exploring other options, current vaccines have something very important to offer older adults.”
Infectious disease expert William Schaffner, MD, of Nashville’s Vanderbilt University, tells WebMD that more effective flu shots may be available in as little as three years.
He says concerns about the possibility of a pandemic of highly deadly bird flu have been a wake-up call to both public and private vaccine researchers.
“Thanks to bird flu, the U.S. government and vaccine industry have invested more money and effort into coming up with a better influenza vaccine in the last three years than they have in the previous 30,” he says.
Just as better vaccines will help protect the most vulnerable populations, so will better strategies for using the vaccines that are currently available, Schaffner says.
One such strategy is vaccinating everyone to reduce the chances that elderly people and sick people with compromised immune systems will be exposed.
This is especially important for people who are in frequent contact with the elderly and sick, such as health care workers.
“Only about half of health care workers in the U.S. get vaccinated,” he says. “The reasons people who ought to know better give for not getting flu shots are, to use my son’s words, lame.”