US Flu VE Data for 2019-2020

At a glance

Influenza vaccine effectiveness from the US Flu VE Network for the 2019-2020 U.S. flu season. Adjusted vaccine effectiveness against flu illness for all ages was 39%.

Reference

Tenforde et, al, 2021

Description of patients enrolled in the US Flu VE Network, 2019-2020

Age

Age Number % Total
6 months-8 years 2011 23
9-17 years 1193 13
18-49 years 3258 37
50-64 years 1348 15
65+ years 1035 12

Sex

Sex Number % Total
Male 3675 42
Female 5169 58
Unknown 1 <1

Race/ethnicity

Race Number % Total
White, non-Hispanic 894 10
Black, non-Hispanic 834 9
Hispanic 801 9
Other, non-Hispanic 6294 71
Unknown 22 <1

Influenza A or B viruses

End of season influenza vaccine effectiveness for all vaccine types, against influenza A or B viruses

Age group (years) Influenza positive
Total		 Vaccinated influenza positive
(% vaccinated)		 Influenza negative
Total		 Vaccinated influenza negative
(% vaccinated)		 Adjusted VE % Adjusted 95% CI
All ages 2722 1140 (42) 6123 3388 (55) 39 (32, 44)
6 mos–8 646 269 (42) 1365 759 (56) 34 (19, 46)
9–17 471 155 (33) 722 324 (45) 40 (22, 53)
18–49 1056 388 (37) 2202 991 (45) 34 (23, 44)
50–64 350 180 (51) 998 619 (62) 40 (22, 54)
≥65 199 148 (74) 836 695 (83) 39 (9, 59)

Influenza A(H1N1)pdm09 viruses

End of season influenza vaccine effectiveness for all vaccine types, against influenza A(H1N1)pdm09 viruses

Age group (years) Influenza positive
Total		 Vaccinated influenza positive
(% vaccinated)		 Influenza negative
Total		 Vaccinated influenza negative
(% vaccinated)		 Adjusted VE % Adjusted 95% CI
All ages 1405 679 (48) 6123 3388 (55) 30 (21, 39)
6 mos–8 277 133 (48) 1365 759 (56) 23 (-3, 42)
9–17 132 53 (40) 722 324 (45) 29 (-7, 52)
18–49 576 242 (42) 2202 991 (45) 26 (9, 39)
50–64 273 142 (52) 998 619 (62) 40 (20, 56)
≥65 147 109 (74) 836 695 (83) 42 (9, 64)

Influenza B/Victoria viruses

End of season influenza vaccine effectiveness for all vaccine types, against influenza B/Victoria viruses

Age group (years) Influenza positive
Total		 Vaccinated influenza positive
(% vaccinated)		 Influenza negative
Total		 Vaccinated influenza negative
(% vaccinated)		 Adjusted VE % Adjusted 95% CI
All ages 1209 415 (34) 6123 3388 (55) 45 (37, 52)
6 mos–8 348 129 (37) 1365 759 (56) 39 (20, 54)
9–17 329 100 (30) 722 324 (45) 43 (23, 58)
18–49 434 128 (29) 2202 991 (45) 45 (30, 56)
50–64 56 27 (48) 998 619 (62) 44 (0, 68)
≥65 42 31 (74) 836 695 (83) 34 (-40, 69)

US Flu VE Network

Influenza virus type and subtype among influenza-positive patients, US Flu VE Network, 2019-2020

Virus Type Number % Total
Influenza A 1,504 55
H3N2 29 1
H1N1pdm09 1,405 52
A, Not subtyped 70 3
Influenza B 1,229 45
B Yamagata 6 <1
B Victoria 1,209 44
Lineage not determined 13 <1
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Content Source:
National Center for Immunization and Respiratory Diseases (NCIRD)