This season's flu vaccine is 45 percent effective, researchers say

This season's flu vaccine is 45 percent effective, researchers say
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This season's flu vaccine is estimated to be 45 percent effective, an improvement over previous years, according to a report published Thursday by the Centers for Disease Control and Prevention (CDC). 

The report, published by researchers from CDC and several other universities, used data from 4,112 children and adults to conclude the vaccine has "significantly" reduced medical visits associated with the flu so far this season.  

The effectiveness of the vaccine could drop as the flu season continues and new strains potentially emerge that aren't protected by the vaccine. 

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The vaccine is developed annually to protect against three or four strains of the flu virus that researchers predict will be most prevalent in the upcoming season. 

Last season's vaccine was only 29 percent effective, largely because of a strain that began circulating during the second half of the flu season. 

Flu activity in the U.S. remains high, the CDC says. Flu activity typically peaks between December and February, but cases can continue until May. 

The CDC estimates there have been at least 26 million flu illnesses so far this season, including 14,000 deaths.

More children and adolescents have died of the flu so far this season compared to similar points in previous seasons. 

More than 90 cases of flu-related deaths have been reported in individuals under the age of 18. 

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The CDC recommends annual vaccination against the flu for all people living in the U.S. who are older than 6 months. 

Still, polls show many people don't get the flu shot because they don't believe it's effective or are worried about potential side effects. 

The CDC says side effects from the vaccine are typically mild, and getting the shot is the best way to protect against the flu. 

Experts say flu symptoms can be less severe in an individual who is vaccinated but still becomes ill.