Season's Flu Vaccine Just 23 Percent Effective: CDC

By Kara Seymour

How effective is the flu vaccine?

This year, only about 23 percent, says a new report from the Centers for Disease Control.

Since 2004, the CDC has analyzed the effectiveness of the flu shot and the results have ranged from 10 to 60 percent. This season’s vaccine had “reduced protection,” leaving even those who got the shot highly susceptible to contracting the flu, according to the CDC.

The CDC considers ”effectiveness” as the amount the vaccine reduced a person’s risk of having to go to the doctor because of flu.

One factor that determines how well a flu vaccine works is the similarity between the flu viruses used when producing it and the flu viruses that actually circulate, the CDC said in summarizing the report.

Many of this season’s predominant viruses have “drifted” from the original vaccine virus, the CDC explained.

“Health care providers should advise patients at high risk to call promptly if they get symptoms of influenza,” said Joe Bresee, branch chief in CDC’s Influenza Division. Those that are high risk include the elderly, children, pregnant woman and people with certain medical conditions.

The CDC said it would still recommend that people get a flu vaccine even during seasons when “drifted” viruses spread. The vaccination can prevent some infections and reduce the severity of the disease, it said.