Flu shots only 9% effective for elderly MEDICINE

FILE - In this Tuesday, Jan. 15, 2013 file photo, Carlos Maisonet, 73, reacts as Dr. Eva Berrios-Colon, a professor at Touro College of Pharmacy, injects him with flu vaccine during a visit to the faculty practice center at Brooklyn Hospital in New York. Health officials said Thursday, Feb. 21, 2013 this season's flu shot was only 9 percent effective in protecting seniors against the most common and dangerous flu bug. Flu vaccine tends to protect younger people better than older ones and is never 100 percent effective. But experts say the preliminary results are disappointing and highlight the need for a better vaccine. (AP Photo/Bebeto Matthews, File) less FILE - In this Tuesday, Jan. 15, 2013 file photo, Carlos Maisonet, 73, reacts as Dr. Eva Berrios-Colon, a professor at Touro College of Pharmacy, injects him with flu vaccine during a visit to the faculty ... more Photo: Bebeto Matthews, Associated Press Photo: Bebeto Matthews, Associated Press Image 1 of / 1 Caption Close Flu shots only 9% effective for elderly 1 / 1 Back to Gallery

Atlanta --

It turns out that this year's flu shot is doing a startlingly dismal job of protecting senior citizens, the most vulnerable age group.

The vaccine is proving only 9 percent effective in people 65 and older against the harsh strain of the flu that is predominant this season, the Centers for Disease Control and Prevention said Thursday.

Health officials are baffled as to why this is so. But the findings help explain why so many older people have been hospitalized with the flu this year.

Overall, across the age groups studied, the vaccine's effectiveness was found to be a moderate 56 percent, which means those who got a shot have a 56 percent lower chance of winding up at the doctor with the flu. That is somewhat worse than in other years.

This flu season had some of the highest hospitalization rates in a decade for people 65 and older, at 146 per 100,000 people.