Flu Vaccine Update: CDC Says it's Less Effective Than Expected, Children's Nasal Spray has Zero Effect

The flu vaccine released this year is less effective than previously thought, showing only 18 percent effectiveness against the H3N2 dominant strain, according to the U.S. Centers for Disease Control and Prevention (CDC).

Federal officials this week said this season's flu vaccine, already acknowledged to be highly ineffective, is performing even worse than earlier estimated, according to HealthjDay, a National Institutes of Health online news publication.

The CDC said it was approximately 50 percent effective, then it was down to 23 percent effective and now it's even lower than that at 18 percent.

The flu vaccine for children are even less effective. The injected vaccine is only at most 15 percent effective for children the Centers for Disease Control and Prevention said in a released statement.

Even worse, the nasal spray vaccine has zero effect on them, it said. "Neither vaccine worked well in protecting against H3N2 viruses this season" for children, it said.

"Physicians should be aware that all hospitalized patients and all outpatients at high risk for serious complications should be treated as soon as possible with one of three available influenza antiviral medications if influenza is suspected, regardless of a patient's vaccination status and without waiting for confirmatory testing," says Joe Bresee, branch chief in CDC's Influenza Division. "Health care providers should advise patients at high risk to call promptly if they get symptoms of influenza."

This flu season, the CDC coverage charts show that early season vaccinations (October and November of last year) were just under 40 percent of the U.S. population. Children were only slightly higher, at 42 percent.