Spokane County saw a steep increase in flu hospitalizations last season – largely because of the high number of infected seniors, said Dorothy MacEachern, an epidemiologist with the Spokane Regional Health District.
“It was a tough year for the elderly and the flu last year,” she said. The health district announced the first of the season’s two flu deaths – a woman in her 80s – in January.
And for that population, last season’s flu vaccine was little help.
While last year’s vaccine reduced the risk for outpatient medical visits resulting from flu by about one-half to two-thirds for most people, the vaccine’s effectiveness was much lower for people ages 65 and older, according to a report issued by the Centers for Disease Control and Prevention.
But, the CDC says, vaccination remains the best way to prevent flu, and the finding shouldn’t discourage future vaccinations among older people, who face greater risk for more serious illness and complications from flu.
The flu vaccine normally protects against three strains of influenza: two A strains and one B strain. One of the A strains, H3N2, caused much of last season’s serious illness in the U.S. But in people 65 and older, the vaccine’s effectiveness against H3N2 was measured at just 9 percent, according to the report.
One possible explanation: Some older adults didn’t mount an effective immune response to the strain. Flu vaccine works by stimulating the immune system to develop antibodies in the body, protecting against infection with the viruses in the vaccine.
A high-dose vaccine formulated for people 65 and older, marketed as Fluzone High-Dose, got approval from the U.S. Food and Drug Administration in 2009.
Studies have found it prompts a stronger immune response among seniors than a standard dose, although it’s not known whether that leads to better flu prevention, according to the CDC. A study to determine its effectiveness is expected to be done in a year or two.
In Spokane County, relatively few older people have rolled up their sleeves for high-dose shots, MacEachern said.
“We do know that older folks are pretty good at getting their vaccine, but sometimes habits are hard to change,” she said. “They might feel less inclined to get something new, like this new high-dose shot.”
MacEachern said that while vaccination isn’t perfect protection, it’s a valuable measure of protection, backed up with healthy habits such as good hand washing and avoiding crowds during flu season.
Every flu season is different, she added.
“Even though (last year’s vaccine) didn’t prevent as much illness as we certainly would have liked, it minimized it and prevented some hospitalizations and prevented some deaths so that the worst outcomes were largely prevented,” MacEachern said.