Past Seasons’ Vaccine Effectiveness Estimates
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. Information on how these estimates are calculated can be found on CDC’s web page How Flu Vaccine Effectiveness and Efficacy are Measured.
Table. Adjusted vaccine effectiveness estimates for influenza seasons from 2004-2022**
CDC calculates vaccine effectiveness estimates through the U.S. VE Network
|
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Unpublished |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 |
||
| Flannery 2018 | WI, MI, PA, TX, WA | 7,410 |
40 |
32, 46 | |
| Rolfes 2019 | WI, MI, PA, TX, WA | 8,436 |
38 |
31, 43 | |
| Flannery 2019 | WI, MI, PA, TX, WA | 10,041 |
29 |
21, 35 | |
| Tenforde 2021 | WI, MI, PA, TX, WA | 8,845 |
39 |
32, 44 | |
| n/a | n/a | n/a |
n/a |
||
| Price 2022 | CA, MI, PA, TN, TX, WA, WI | 4,312 |
36 |
21, 48 |
*From 2004-2005 through 2010-2011, the Flu VE Network also enrolled inpatients.
**2020-2021 flu vaccine effectiveness was not estimated due to low flu virus circulation during the 2020-2021 flu season.
† Vaccine effectiveness (VE) estimates for the 2008-2009 flu season have not been published.
‡ Number of patients used in VE calculation.
