The benefits of receiving an influenza immunization may be twofold.
In addition to preventing respiratory illness, the flu vaccine also guards against influenza-related pneumonia, according to a JAMA study released Monday.
Researchers took data from the Etiology of Pneumonia in the Community, or EPIC, a study conducted at academic medical centers in Chicago, Memphis, Nashville and Salt Lake City in collaboration with the Centers for Disease Control and Prevention. From January 2010 through June 2012, they identified 2,767 patients hospitalized with community-acquired pneumonia and determined that 6% had pneumonia caused by influenza. Researchers then pinpointed which ones had previously received an influenza vaccination. The patients with non-influenza pneumonia served as a control group.
"We found patients who received the influenza vaccination had a substantially lower risk,” said lead author Dr. Carlos Grijalva, an associate professor of health policy at Vanderbilt University in Nashville.
Specifically, they found that the vaccine was 57% effective in fighting influenza pneumonia.
“That means that approximately 57% of hospitalizations for influenza pneumonia could be prevented through vaccination,” Grijalva concluded, adding that the benefit extended to both children and adults.
Grijalva said there have been previous studies with similar design, but they had studied illness while this study examined immunization's success at preventing serious complications of the illness.
“I think it's very useful to highlight how the influenza vaccine provides benefits that are not restricted to influenza,” he said. “It's a good time to raise awareness of that.”
While the prevention of hospitalizations obviously saves the health system money, Grijalava said it hasn't been determined how much was saved by vaccinations or the amount of return on the vaccine's investment.
“It's a good question—but it's not something we explored in this study,” he said.
Each flu season, scientists must predict what form the virus may take and develop a vaccine that will best combat that particular strain. In their report, Grijalva and colleagues acknowledged that, in the flu seasons studied, a good job was done in matching vaccine with the circulating influenza strains and this may have skewed their findings. The study also only focused on hospitalized patients, so additional studies done in outpatient settings would complement these findings.
Grijalva also said that, in general, vaccines are of less benefit to older adults and patients with malignancies and HIV. New strategies need to be developed to help these patients, he said, adding that this could include new vaccines or combinations of vaccines.