Table 5.
Vaccine Effectiveness Estimates Against Influenza A(H1N1)pdm09, US Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN), 2018-2019
| Characteristic | No. | Vaccinated Cases/Total Cases (%) | Vaccinated Influenza-Negative Controls/ Total Influenza-Negative Controls (%) | Unadjusted VE (95% CI) | Adjusted VE (95% CI) |
|---|---|---|---|---|---|
| Alla,b | 2447 | 118/225 (52) | 1568/2222 (71) | 54 (39–65) | 51 (25–68) |
| By age groupc | |||||
| 18 to ≤56 yd,e | 832 | 32/87 (37) | 443/745 (59) | 60 (37–75) | 63 (22–82) |
| >56 to ≤69 yf,g | 831 | 40/79 (51) | 527/752 (70) | 56 (30–73) | 44 (–7 to 71) |
| >69 yh,i | 784 | 46/59 (78) | 598/725 (82) | 25 (–48 to 60) | 16 (–147 to 71) |
| By influenza vaccination historyj | |||||
| Never/rarelyk,l | 568 | 7/84 (8) | 87/484 (18) | 58 (11–83) | 58 (–7 to 84) |
| Always/almost alwaysm,n | 1719 | 107/131 (82) | 1405/1588 (88) | 42 (6–63) | 40 (–4 to 65) |
Vaccination was defined as affirmative self-report with known or approximate date and location of vaccination provided and/or documented evidence of vaccination.
Abbreviations: CI, confidence interval; VE, vaccine effectiveness.
aVE adjusted for age (tertiles), site, tertile of illness onset date relative to peak of influenza A(H1N1) cases, days between onset and specimen collection (<5 vs ≥5 days), black race, and frailty.
bData balanced on vaccination habit, number of high-risk conditions, home oxygen use, ≥1 hospitalization in past year, current tobacco smoking (yes/no), and metabolic disorders.
cDefined as tertiles of age in years in full dataset.
dVE adjusted for site, tertile of illness onset date relative to peak of influenza A(H1N1)pdm09 cases, days between onset and specimen collection (<5 vs ≥5 days), and obstructive lung disorders.
eData balanced on vaccination habit, number of high-risk conditions, home oxygen use, and ≥1 hospitalization in past year.
fVE adjusted for tertile of illness onset date relative to peak of influenza A(H1N1)pdm09 cases and days between onset and specimen collection (<5 vs ≥5 days).
gData balanced on vaccination habit, number of high-risk conditions, home oxygen use, ≥1 hospitalization in past year, heart disease, obstructive lung disorders, and site.
hVE adjusted for tertile of illness onset date relative to peak of influenza A(H1N1)pdm09 cases, days between onset and specimen collection, and home oxygen use.
iData balanced on vaccination habit, current tobacco smoking (yes/no), and obstructive lung disorders.
jInfluenza vaccination history defined by patient self-report during enrollment interview; patients reporting vaccination history “sometimes” are excluded (n = 160).
kVE adjusted for tertile of illness onset date relative to peak of influenza A(H1N1)pdm09 cases and days between onset and specimen collection.
lData balanced on number of high-risk conditions, home oxygen use, ≥1 hospitalization in past year, heart disease, neurologic disorders, congestive heart failure, and site.
mVE adjusted for tertile of illness onset date relative to peak of influenza A(H1N1)pdm09 cases, days between onset and specimen collection, and sex.
nData balanced on age, number of high-risk conditions, home oxygen use, heart disease, current tobacco use (yes/no), and site.