By Gene Emery, Reuters
BOSTON — Annual influenza vaccines save the lives of elderly people, even though they are less effective in this group compared to younger people, U.S. researchers reported on Wednesday.
Ten years of data from three regions of the United States show that the vaccine reduces the risk of hospitalization from pneumonia or the flu by 27 percent in the elderly, and cuts the death rate in half.
The elderly make up the bulk of the 36,000 people who die from flu each year in the United States.
“What we do show, definitely, is that there is a substantial benefit,” said Kristin Nichol of the Minneapolis Veterans Affairs Medical Center, leader of the team.
They found that the benefits of the vaccine varied from community to community and from year to year, depending on whether the shots were designed to combat the flu strains that occurred.
“In seasons with a poor match, vaccine effectiveness was 37 percent; in seasons with a good match, vaccine effectiveness was 52 percent” in reducing death, the researchers wrote in their report, published in the New England Journal of Medicine.
Overall, data from more than 70,000 people per season showed that the injections are effective.
Nonetheless, only about 65 percent of people over 64 get a flu shot each year, in part because health-care providers often fail to recommend them, Nichol said.
Last week, researchers reported in Lancet Infectious Diseases that previous research may have inflated the flu vaccine’s effectiveness in the elderly.
Nichol said in a telephone interview that the new study addresses many of the concerns raised in the Lancet paper.
There is no disagreement that the shots could be more effective. Many studies show people who are vaccinated against flu are less likely to die during the flu season, typically October to March in North America.
Flu expert Dr. John Treanor of the University of Rochester Medical Center in New York said that while half of the people who died had been vaccinated, this did not mean the immunizations were not worthwhile.
“Some of these deaths were probably due to other viruses, such as respiratory syncytial virus, that can mimic influenza, but many probably represent vaccine failures,” Treanor wrote in a commentary.
The study of people enrolled in three health maintenance organizations in Minnesota, Wisconsin, Oregon, New York and Washington state found that the vaccines always reduced the death rate, no matter what age group and whether the person faced a high risk of illness because of pre-existing medical problems.
But the flu vaccine became less effective with age. Researchers know that the immune systems of elderly people gradually become weaker and less able to respond to the booster effects of a vaccine.
Nichol noted that the study did not look at whether the vaccine was worthwhile among the frailest elderly, including nursing home residents. More effective vaccines for the elderly are under development but have not yet been approved for use in the United States.