Flu shot not as effective against this year's strain, CDC warns

LOS ANGELES (KABC) -- Health officials are warning that the flu vaccine isn't very effective this year. Officials say the vaccine does not protect well against the dominant strain, which tends to cause more deaths and hospitalizations, especially in the elderly.

The Centers for Disease Control and Prevention sent an advisory to doctors and clinicians, warning them that 52 percent of flu samples were not a good match for the current vaccine. Making matters worse, this year's strain, the H3N2, is especially bad.

"The H3N2 strain that's in the community this year tends to be one that leads to more hospitalizations, much more severe than some of the other strains," said Dr. Richard Besser, ABC News chief health and medical editor.

According to the CDC, the virus has mutated or drifted, making the flu vaccine less effective, and it's too late to make any adjustments to the vaccine. Those at highest risk include children younger than 2, adults over 65 and people with asthma, heart disease, weakened immune systems or certain other chronic conditions.

Doctors are being told to immediately put them on antiviral medications if they show any symptoms of the flu.

"I think this is a year where people have to take extra care, you want to wash your hands regularly, you want to make sure you are covering coughs and sneezes," said Besser.

On average, about 24,000 Americans die each flu season, according to the CDC.

In a good year, the flu vaccine is effective in about 60 percent of cases. CDC officials think the vaccine should provide some protection and still are urging people to get vaccinated.

For more information on the flu vaccine, visit www.cdc.gov/flu/index.htm.