CHICAGO (WLS) -- Health officials say this year's flu vaccine is even less effective than previously reported, showing just 18 percent effectiveness against the dominant strain of flu.
The U.S. Centers for Disease Control says effectiveness is down from the 23 percent protection level estimated for the flu shot earlier in the season. The situation for children is even worse, as the CDC said the effectiveness of the injected vaccine for kids between 2 and 8 years old is just 15 percent.
Health officials say the nasal spray version of the vaccine may not protect young children at all.
Health officials also say the H3N2 flu strain that is current circulating was not factored into this season's vaccine because decisions about which strains to target were made in Feb. 2014.