# 2019-2020 flu season: active virus strains and the flu shot

**URL:** <https://boards.straightdope.com/t/2019-2020-flu-season-active-virus-strains-and-the-flu-shot/845965>\
**Category:** Factual Questions\
**Created:** [January 5, 2020, 7:16am UTC](https://boards.straightdope.com/t/2019-2020-flu-season-active-virus-strains-and-the-flu-shot/845965 "2020-01-05T07:16:54Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![gkster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gkster/32/14107_2.png) [@gkster](https://boards.straightdope.com/u/gkster)\
**Post date:** [January 5, 2020, 7:16am UTC](https://boards.straightdope.com/t/2019-2020-flu-season-active-virus-strains-and-the-flu-shot/845965/1 "2020-01-05T07:16:54Z")

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Can someone familiar with flu strains and vaccines help with interpreting the CDC and FDA websites? Basically I’m remembering last year when flu shots were supposedly just 30% effective and wondering whether the flu shots that family members and I had last month are effective against the viruses going around right now. And I just realized that one of my kids was away at college and probably didn’t get a shot.

The CDC site says that these are the strains going around:  
Nationally influenza **B/Victoria** viruses have been reported more frequently than other influenza viruses this season followed by **A(H1N1)pdm09**.

> **[Weekly U.S. Influenza Surveillance Report](https://www.cdc.gov/flu/weekly/#PublicHealthLaboratories)**
>
> Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.

And the FDA says:  
The committee recommended that the trivalent formulation influenza vaccines for the U.S. 2019-2020 influenza season contain the following:  
an A/Brisbane/02/2018 **(H1N1)pdm09**-like virus;  
an A/Kansas/14/2017 (H3N2)-like virus;  
a B/Colorado/06/2017-like virus ( **B/Victoria** lineage).  
The committee also recommended that quadrivalent influenza vaccines contain the above three strains and the following additional B strain:  
a B/Phuket/3073/2013-like virus (B/Yamagata lineage)  
[https://www.fda.gov/vaccines-blood-biologics/lot-release/influenza-vaccine-2019-2020-season](https://www.fda.gov/vaccines-blood-biologics/lot-release/influenza-vaccine-2019-2020-season)

I bolded what look to me like matches between virus strains currently going around and strains in the shots. But I don’t know enough about flu strain classifications to know if these really are matches or not.