News for North Texas
Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

Why The Flu Vaccine Doesn't Always Work, And Why So Many People Don't Get It

A photo of disposable face masks.

Texas is first in flu according to Walgreens, and both the Dallas County and Tarrant County health departments are tracking a steep uptick in the number of positive tests.

According to the Centers for Disease Control and Prevention, this year's vaccine is thought to be about 32 percent effective, just like last year's.

A tough sell?

According to the CDC, flu vaccination rates for adults in recent years hover just over 40 percent. Dr. Edward Dominguez thinks he knows why.

"Many people feel that all of the available vaccines for influenza in the United States can actually cause the flu," he said. "And these are killed vaccines; they can't cause anything other than pain and local inflammation. Or you can be allergic to the components. None of these vaccines can actually cause the flu."

Dominguez is an infectious disease specialist at Methodist Dallas Medical Center. He says people are also turned off to getting the vaccine when they hear it's only 32 percent effective.

Believe it or not, he says, that's not unusual.

"It turns out that that's about as good the flu vaccine has always been," he said. "Somewhere between 30-to-50 percent effective."

32 percent... and dropping?

Dominguez says by the time the season's over, we may discover the vaccine wasn't even 32 percent effective. That's because one of the strains of flu the shot protects against might be mutating. That means what's in the vaccine is a little different than the virus actually going around.

"And it doesn't take much of a mutation for that particular virus to become more aggressive, if you will, and for the vaccine to become less effective, even though it's very closely related to last year's strain," said Dominguez.

Dallas County reports this season, about 30 percent of flu tests from hospital labs were coming back positive in late December. At the same time last season, only about 6 percent of flu tests were positive.

"We won't know exactly how effective this vaccine was until we're past this flu season," Dominguez said. "I think if you talk to enough physicians, they're going to tell you that it's probably less than 30 percent."

Firsthand knowledge

And this season, Dominguez can speak from experience. He got the vaccine like he does every year and still got the flu-- then ended up in the emergency room with pneumonia. 

Courtney Collins has been working as a broadcast journalist since graduating from the Medill School of Journalism at Northwestern University in 2004. Before coming to KERA in 2011, Courtney worked as a reporter for NPR member station WAMU in Washington D.C. While there she covered daily news and reported for the station’s weekly news magazine, Metro Connection.