Table 1.
Characteristics of the Study Population
| Characteristics | Vaccinated n=2,632,906 |
Vaccinated n=3,238,532 |
Total N=5,871,438 |
p-Value |
|---|---|---|---|---|
| Age, years, mean (SD) | 57.7 (18.0) | 66.3 (14.4) | 62.4 (16.7) | <0.0001 |
| Age group (%) | <0.0001 | |||
| <45 | 29.7 | 10.6 | 19.1 | |
| 45–54 | 14.6 | 10.3 | 12.2 | |
| 55–64 | 16.8 | 18.5 | 17.8 | |
| 65–74 | 22.7 | 36.7 | 30.4 | |
| ≥75 | 16.2 | 23.9 | 20.5 | |
| Sex, n (%) | <0.0001 | |||
| Female | 279,943 (10.6) | 269,247 (8.3) | 549,190 (9.4) | |
| Male | 2,352,958 (89.4) | 2,969,285 (91.7) | 5,322,243 (90.6) | |
| Race and ethnicity (%) | ||||
| White | 66.9 | 66.7 | 66.8 | |
| Black | 16.1 | 18.2 | 17.2 | |
| Hispanic | 6.6 | 7.0 | 6.9 | |
| Asian/Pacific Islander | 1.7 | 2.0 | 1.9 | |
| American Indian/Alaskan Native | 0.8 | 0.6 | 0.7 | |
| Mixed | 0.9 | 0.8 | 0.8 | |
| Other (missing, declined answer, unknown to patient) | 7.0 | 4.7 | 5.7 | |
| Urban versus rural (%) | <0.0001 | |||
| Urban | 62.8 | 68.0 | 65.7 | |
| Rural | 35.7 | 30.9 | 33.0 | |
| Highly rural | 1.5 | 1.1 | 1.3 | |
| Previous influenza vaccination (2019–2020 season), n (%) | 30.0 | 62.0 | 47.9 | <0.0001 |
| Charlson Comorbidity Index, median (IQR) | 0 [0–1] | 1 [0–2] | 0 [0–1] | <0.0001 |
| Charlson Comorbidity Index (%) | <0.0001 | |||
| 0 | 67.2 | 46.8 | 56.0 | |
| 1 | 16.1 | 22.0 | 19.4 | |
| 2 | 6.8 | 11.2 | 9.2 | |
| ≥3 | 9.9 | 20.0 | 15.4 | |
| Geographic region | <0.0001 | |||
| North Atlantic | 21.0 | 22.5 | 21.8 | |
| Midwest | 20.8 | 20.9 | 20.9 | |
| Southwest | 20.6 | 21.2 | 20.9 | |
| Pacific | 17.6 | 18.4 | 18.1 | |
| Continental | 20.0 | 17.0 | 18.3 | |
| Service connectedness | ||||
| None | 36.1 | 36.2 | 36.2 | |
| <50% | 23.2 | 22.6 | 22.9 | |
| ≥50% | 40.7 | 41.2 | 40.9 |