Past Seasons' Vaccine Effectiveness Estimates

What to know

These pages include information about the seasonal flu vaccine effectiveness estimates from past seasons, including tables of the estimated vaccine effectiveness (and 95% confidence interval [CI]) by age group and virus subtype.

Past Seasons Estimates

Table. Adjusted vaccine effectiveness estimates for influenza seasons from 2004-2025

Influenza Season

Reference

Study Site(s)

No. of Patients

Adjusted Overall VE (%)

95% CI

2004-05*

WI

762

10

-36, 40

2005-06*

WI

346

21

-52, 59

2006-07*

WI

871

52

22, 70

2007-08*

WI

1,914

37

22, 49

2008-09*

Unpublished

WI, MI, NY, TN

6,713

41

30, 50

2009-10*

WI, MI, NY, TN

6,757

56

23, 75

2010-11*

WI, MI, NY, TN

4,757

60

53, 66

WI, MI, PA, TX, WA

4,771

47

36, 56

WI, MI, PA, TX, WA

6,452

49

43, 55

WI, MI, PA, TX, WA

5,999

52

44, 59

WI, MI, PA, TX, WA

9,311

19

10, 27

WI, MI, PA, TX, WA

6,879

48

41, 55

WI, MI, PA, TX, WA 7,410

40

32, 46

WI, MI, PA, TX, WA 8,436

38

31, 43

WI, MI, PA, TX, WA 10,041

29

21, 35

2019-20

WI, MI, PA, TX, WA 8,845

39

32, 44

2020-21**

n/a n/a n/a

n/a

2021-22

CA, MI, PA, TN, TX, WA, WI 4,312

36

21, 48

2022-23

MI, PA, TX, WA, AZ, MO, OH 2,561 30 -9, 54

2023-24***

AZ, MI, MO, PA, OH, TX, WA 9,061 44 36, 51

2024-25††

Frutos 2025 MN, WI, UT, CA, OR, WA, IN, CO 139,558 56 54, 58

*From 2004-2005 through 2010-2011, the Flu VE Network also enrolled inpatients.

Vaccine effectiveness (VE) estimates for the 2008-2009 flu season have not been published.

**2020-2021 flu vaccine effectiveness was not estimated due to low influenza virus circulation during the 2020-2021 flu season.

Number of patients used in VE calculation.

***Overall VE was calculated for this table to be consistent with what has been reported historically and is available for comparison with historical estimates. All other 2023-2024 VE estimates are reported by age group.

††VE estimates for 2024-2025 flu season are preliminary.

Information on how these estimates are calculated can be found on 星空娱乐官网's web page How Flu Vaccine Effectiveness and Efficacy are Measured.

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