TABLE 1.
Characteristics of influenza vaccine recipients 18–49 and 50–64 years of age by vaccine type (after inverse probability of treatment weighting).
| n (%) | 18–49 years | 50–64 years | ||||||
|---|---|---|---|---|---|---|---|---|
| SD egg‐based | SD cell‐based | p value | ASD | SD egg‐based | SD cell‐based | p value | ASD | |
| n = 333,625 | n = 143,412 | n = 255,643 | n = 115,654 | |||||
| Demographic characteristics | ||||||||
| Age at index date, years | 0.926 | 0.000 | 0.810 | 0.001 | ||||
| Mean (std dev) | 35.6 (9.0) | 35.6 (9.0) | 57.4 (4.3) | 57.4 (4.3) | ||||
| Median (Q1, Q3) | 37 (29, 43) | 37 (29, 43) | 58 (54, 61) | 58 (54, 61) | ||||
| Min, max | 18, 49 | 18, 49 | 50, 64 | 50, 64 | ||||
| Age at index date, years | 0.423 | 0.004 | 0.770 | 0.001 | ||||
| 18–29 | 89,842 (26.9) | 38,808 (27.1) | N/A | N/A | ||||
| 30–39 | 112,293 (33.7) | 48,007 (33.5) | N/A | N/A | ||||
| 40–49 | 131,490 (39.4) | 56,597 (39.5) | N/A | N/A | ||||
| 50–59 | N/A | N/A | 160,538 (62.8) | 72,686 (62.8) | ||||
| 60–64 | N/A | N/A | 95,105 (37.2) | 42,968 (37.2) | ||||
| Sex | 0.907 | 0.000 | 0.969 | 0.000 | ||||
| Female | 203,787 (61.1) | 87,626 (61.1) | 141,495 (55.3) | 64,005 (55.3) | ||||
| Male | 129,838 (38.9) | 55,786 (38.9) | 114,148 (44.7) | 51,649 (44.7) | ||||
| Race/ethnicity | 0.723 | 0.005 | 0.815 | 0.004 | ||||
| Non‐Hispanic White | 81,286 (24.4) | 35,187 (24.5) | 82,048 (32.1) | 37,331 (32.3) | ||||
| Non‐Hispanic Black | 15,141 (4.5) | 6502 (4.5) | 18,343 (7.2) | 8293 (7.2) | ||||
| Hispanic | 148,706 (44.6) | 63,646 (44.4) | 102,332 (40.0) | 46,076 (39.8) | ||||
| Non‐Hispanic Asian | 59,937 (18.0) | 25,792 (18.0) | 38,777 (15.2) | 17,561 (15.2) | ||||
| Other/unknown | 28,555 (8.6) | 12,285 (8.6) | 14,142 (5.5) | 6393 (5.5) | ||||
| Medicaid | 38,146 (11.4) | 16,391 (11.4) | 0.967 | 0.000 | 19,547 (7.6) | 8849 (7.7) | 0.815 | 0.004 |
| Neighborhood median household income | 0.890 | 0.003 | 0.885 | 0.004 | ||||
| < $40,000 | 4997 (1.5) | 2148 (1.5) | 3732 (1.5) | 1686 (1.5) | ||||
| $40,000–$59,999 | 46,136 (13.8) | 19,688 (13.7) | 33,442 (13.1) | 14,989 (13.0) | ||||
| $60,000–$79,999 | 74,178 (22.2) | 31,827 (22.2) | 54,416 (21.3) | 24,608 (21.3) | ||||
| ≥ $80,000 | 207,784 (62.3) | 89,520 (62.4) | 163,358 (63.9) | 74,052 (64.0) | ||||
| Unknown | 531 (0.2) | 229 (0.2) | 696 (0.3) | 319 (0.3) | ||||
| Smoking a | 0.976 | 0.001 | 0.995 | 0.000 | ||||
| No | 263,105 (78.9) | 113,062 (78.8) | 193,424 (75.7) | 87,490 (75.6) | ||||
| Yes | 36,477 (10.9) | 15,709 (11.0) | 48,072 (18.8) | 21,764 (18.8) | ||||
| Unknown | 34,043 (10.2) | 14,641 (10.2) | 14,147 (5.5) | 6400 (5.5) | ||||
| Clinical characteristics | ||||||||
| Body mass index a , kg/m2 | 0.993 | 0.002 | 1.000 | 0.001 | ||||
| < 18.5 | 4557 (1.4) | 1971 (1.4) | 1557 (0.6) | 710 (0.6) | ||||
| 18.5 to < 25 | 79,831 (23.9) | 34,382 (24.0) | 48,830 (19.1) | 22,114 (19.1) | ||||
| 25 to < 30 | 85,028 (25.5) | 36,567 (25.5) | 81,159 (31.7) | 36,720 (31.7) | ||||
| ≥ 30 | 116,957 (35.1) | 50,207 (35.0) | 102,373 (40.0) | 46,280 (40.0) | ||||
| Unknown | 47,252 (14.2) | 20,284 (14.1) | 21,724 (8.5) | 9831 (8.5) | ||||
| Charlson comorbidity score b , c | 0.994 | 0.002 | 0.874 | 0.002 | ||||
| Mean (std dev) | 0.3 (0.8) | 0.3 (0.8) | 0.74 (1.43) | 0.7 (1.4) | ||||
| Median (Q1, Q3) | 0 (0, 0) | 0 (0, 0) | 0 (0, 1) | 0 (0, 1) | ||||
| Min, max | 0, 16 | 0, 13 | 0, 17 | 0, 16 | ||||
| Charlson comorbidity score b , c | 0.983 | 0.001 | 0.994 | 0.000 | ||||
| 0 | 279,325 (83.7) | 120,075 (83.7) | 164,922 (64.5) | 74,634 (64.5) | ||||
| 1 | 39,214 (11.8) | 16,839 (11.7) | 48,449 (19.0) | 21,907 (18.9) | ||||
| ≥ 2 | 15,086 (4.5) | 6499 (4.5) | 42,272 (16.5) | 19,113 (16.5) | ||||
| Frailty index b , d | 0.608 | 0.003 | 0.635 | 0.002 | ||||
| Mean (std dev) | 0.1 (0.0) | 0.1 (0.0) | 0.1 (0.0) | 0.1 (0.0) | ||||
| Median (Q1, Q3) | 0.1 (0.1, 0.1) | 0.1 (0.1, 0.1) | 0.1 (0.1, 0.1) | 0.1 (0.1, 0.1) | ||||
| Min, max | 0.0, 0.4 | 0.1, 0.4 | 0.0, 0.4 | 0.0, 0.4 | ||||
| Frailty index b , d | 0.983 | 0.001 | 1.000 | 0.000 | ||||
| Quartile 1 | 83,382 (25.0) | 35,805 (25.0) | 62,622 (24.5) | 28,312 (24.5) | ||||
| Quartile 2 | 45,896 (13.8) | 19,690 (13.7) | 65,184 (25.5) | 29,498 (25.5) | ||||
| Quartile 3 | 120,932 (36.2) | 51,996 (36.3) | 63,940 (25.0) | 28,932 (25.0) | ||||
| Quartile 4, most frail | 83,415 (25.0) | 35,921 (25.0) | 63,897 (25.0) | 28,911 (25.0) | ||||
| Chronic diseases b | ||||||||
| Kidney disease | 2468 (0.7) | 1061 (0.7) | 0.991 | 0.000 | 9224 (3.6) | 4162 (3.6) | 0.883 | 0.001 |
| Heart disease | 1558 (0.5) | 674 (0.5) | 0.882 | 0.001 | 6475 (2.5) | 2926 (2.5) | 0.961 | 0.000 |
| Liver disease | 7746 (2.3) | 3341 (2.3) | 0.870 | 0.001 | 12,162 (4.8) | 5502 (4.8) | 0.997 | 0.000 |
| Diabetes | 18,387 (5.5) | 7890 (5.5) | 0.891 | 0.000 | 51,824 (20.3) | 23,403 (20.2) | 0.797 | 0.001 |
| Immunocompromised e | 8878 (2.7) | 3818 (2.7) | 0.983 | 0.000 | 10,595 (4.1) | 4797 (4.1) | 0.963 | 0.000 |
| Respiratory conditions b | ||||||||
| Chronic obstructive pulmonary disease, chronic bronchitis, or emphysema | 3912 (1.2) | 1691 (1.2) | 0.854 | 0.001 | 6167 (2.4) | 2804 (2.4) | 0.819 | 0.001 |
| Asthma | 22,261 (6.7) | 9557 (6.7) | 0.913 | 0.000 | 16,762 (6.6) | 7591 (6.6) | 0.937 | 0.000 |
| Healthcare utilization | ||||||||
| Number of outpatient and virtual visits b | 0.995 | 0.001 | 0.999 | 0.001 | ||||
| 0 | 3912 (1.2) | 1691 (1.2) | 10,513 (4.1) | 4766 (4.1) | ||||
| 1–4 | 22,261 (6.7) | 9557 (6.7) | 69,446 (27.2) | 31,419 (27.2) | ||||
| 5–10 | 3912 (1.2) | 1691 (1.2) | 84,261 (33.0) | 38,130 (33.0) | ||||
| ≥ 11 | 22,261 (6.7) | 9557 (6.7) | 91,422 (35.8) | 41,338 (35.7) | ||||
| Number of emergency department visits b | 0.979 | 0.001 | 0.998 | 0.000 | ||||
| 0 | 284,111 (85.2) | 122,120 (85.2) | 215,586 (84.3) | 97,529 (84.3) | ||||
| 1 | 36,296 (10.9) | 15,623 (10.9) | 29,046 (11.4) | 13,147 (11.4) | ||||
| ≥ 2 | 13,218 (4.0) | 5669 (4.0) | 11,011 (4.3) | 4977 (4.3) | ||||
| Number of hospitalizations b | 0.987 | 0.001 | 0.986 | 0.001 | ||||
| 0 | 317,205 (95.1) | 136,338 (95.1) | 245,846 (96.2) | 111,210 (96.2) | ||||
| 1 | 14,195 (4.3) | 6116 (4.3) | 7355 (2.9) | 3339 (2.9) | ||||
| ≥ 2 | 2226 (0.7) | 958 (0.7) | 2442 (1.0) | 1105 (1.0) | ||||
| Preventive care b , f | 122,802 (36.8) | 52,761 (36.8) | 0.902 | 0.000 | 156,647 (61.3) | 70,892 (61.3) | 0.902 | 0.000 |
| Receipt of influenza vaccine g | 244,696 (73.3) | 105,140 (73.3) | 0.822 | 0.001 | 213,891 (83.7) | 96,751 (83.7) | 0.926 | 0.000 |
| Receipt of COVID‐19 vaccine b | 249,791 (74.9) | 107,350 (74.9) | 0.896 | 0.000 | 212,000 (82.9) | 95,872 (82.9) | 0.806 | 0.001 |
| Concomitant vaccines h | 61,917 (18.6) | 26,582 (18.5) | 0.849 | 0.001 | 69,080 (27.0) | 31,303 (27.1) | 0.780 | 0.001 |
| Month of vaccination | 0.982 | 0.002 | 0.986 | 0.002 | ||||
| August 2022 | 11,838 (3.5) | 5088 (3.5) | 10,551 (4.1) | 4773 (4.1) | ||||
| September 2022 | 105,342 (31.6) | 45,326 (31.6) | 93,937 (36.7) | 42,532 (36.8) | ||||
| October 2022 | 105,870 (31.7) | 45,415 (31.7) | 84,077 (32.9) | 37,959 (32.8) | ||||
| November 2022 | 72,285 (21.7) | 31,050 (21.7) | 45,403 (17.8) | 20,527 (17.7) | ||||
| December 2022 | 38,290 (11.5) | 16,533 (11.5) | 21,675 (8.5) | 9863 (8.5) | ||||
Abbreviations: ASD = absolute standardized difference; Q1 = quartile 1; Q3 = quartile 3; SD = standard dose; std dev = standard deviation.
a
Defined in the two years prior to index date.
b
Defined in the one year prior to index date.
c
Possible range: 0–29 [11].
d
Possible range: 0–1 [12].
e
HIV/AIDS, leukemia/lymphoma, congenital/other immunodeficiencies, asplenia/hyposplenia, hematopoietic stem cell transplant/solid organ transplant, and receipt of immunosuppressive medications.
f
Includes screenings, preventive physical exams, and wellness visits.
g
During previous influenza season (August 2021 to April 2022).
h
Administered on index date.