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# That Flu Shot You Had May Not Work This Year


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by 

[Tessa Berenson](https://time.com/author/tessa-berenson/)


![Tessa Berenson](https://static.time.com/v3/assets/bltea6093859af6183b/bltec0484fe1b20c577/698a0ced86f68ed9d96ee9e6/tessa-berenson-author-2020.jpg?branch=production&width=96&quality=75&auto=webp)

## Tessa Berenson


Dec 4, 2014 1:33 PM UTC

![Flu vaccines](https://static.time.com/v3/assets/bltea6093859af6183b/blt7854909363bfce61/6987622d8e06019066457d9f/flu-influenza.jpg?branch=production&width=3840&quality=75&auto=webp&crop=3:2)

Flu vaccines. File photo dated 05/10/09 of a nurse preparing to give a patient a shot from a hypodermic needle, as pregnant women are among those being urged to get the flu vaccine in a major public health drive. Issue date: Monday October 6, 2014\. People with existing health conditions and parents of young children are also being targeted by medics seeking to encourage widespread immunisation against the illness ahead of the winter. See PA story HEALTH Flu. Photo credit should read: David Cheskin/PA Wire URN:21112040

Flu vaccines. File photo dated 05/10/09 of a nurse preparing to give a patient a shot from a hypodermic needle, as pregnant women are among those being urged to get the flu vaccine in a major public health drive. Issue date: Monday October 6, 2014\. People with existing health conditions and parents of young children are also being targeted by medics seeking to encourage widespread immunisation against the illness ahead of the winter. See PA story HEALTH Flu. Photo credit should read: David Cheskin/PA Wire URN:21112040David Cheskin—PA Wire/AP

![Tessa Berenson](https://static.time.com/v3/assets/bltea6093859af6183b/bltec0484fe1b20c577/698a0ced86f68ed9d96ee9e6/tessa-berenson-author-2020.jpg?branch=production&width=3840&quality=75&auto=webp&crop=1:1)

by 

[Tessa Berenson](https://time.com/author/tessa-berenson/)


![Tessa Berenson](https://static.time.com/v3/assets/bltea6093859af6183b/bltec0484fe1b20c577/698a0ced86f68ed9d96ee9e6/tessa-berenson-author-2020.jpg?branch=production&width=96&quality=75&auto=webp)

## Tessa Berenson


Dec 4, 2014 1:33 PM UTC

The Centers of Disease Control and Prevention (CDC) have warned doctors that flu vaccines may not be effective against the most common strain of flu circulating in the U.S..

[According to Reuters](http://www.reuters.com/article/2014/12/04/us-usa-flu-idUSKCN0JI00T20141204), the U.S. health agency issued an advisory to doctors Wednesday saying that of the flu samples they had taken between October 1 and November 22, less than half were good matches for the current flu shots.

The flu shots will still protect against certain strains of the flu, and can help reduce the risk of complications even among the strains that have mutated.

\[[_Reuters_](http://www.reuters.com/article/2014/12/04/us-usa-flu-idUSKCN0JI00T20141204)\]

CDC Says Flu Shots May Not Be Very Effective This Year

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