Table 1. Characteristics of EPICC Study Participants Included in Analyses.
| Characteristic | Participants, No. (%) | P valuea | ||
|---|---|---|---|---|
| Unvaccinated at time of infection (n = 1413) | Postvaccination infection (n = 419) | Total (N = 1832) | ||
| Age group, y | ||||
| 18-44 | 916 (64.8) | 310 (74.0) | 1226 (66.9) | .002 |
| 45-64 | 398 (28.2) | 89 (21.2) | 487 (26.6) | |
| ≥65 | 99 (7.0) | 20 (4.8) | 119 (6.5) | |
| Sex | ||||
| Female | 563 (39.8) | 151 (36.0) | 714 (39.0) | .16 |
| Male | 850 (60.2) | 268 (64.0) | 1118 (61.0) | |
| Race and ethnicityb | ||||
| Asian | 68 (4.8) | 10 (2.4) | 78 (4.3) | <.001 |
| Black or African American | 164 (11.6) | 42 (10.0) | 206 (11.2) | |
| Hispanic or Latinx | 326 (23.1) | 58 (13.8) | 384 (21.0) | |
| White | 737 (52.2) | 273 (65.2) | 1010 (55.1) | |
| Other or missingc | 118 (8.4) | 36 (8.6) | 154 (8.4) | |
| BMI categoryd | ||||
| Underweight or normal weight | 292 (20.7) | 107 (25.5) | 399 (21.8) | .003 |
| Overweight | 577 (40.8) | 183 (43.7) | 760 (41.5) | |
| Obesity | 338 (23.9) | 94 (22.4) | 432 (23.6) | |
| Severe obesity | 206 (14.6) | 35 (8.4) | 241 (13.2) | |
| Charlson Comorbidity Index score | ||||
| 0 | 954 (67.5) | 336 (80.2) | 1290 (70.4) | <.001 |
| 1-2 | 315 (22.3) | 58 (13.8) | 373 (20.4) | |
| 3-4 | 85 (6.0) | 17 (4.1) | 102 (5.6) | |
| ≥5 | 59 (4.2) | 8 (1.9) | 67 (3.7) | |
| Military status | ||||
| Active duty | 817 (57.8) | 309 (73.7) | 1126 (61.5) | <.001 |
| Dependent | 316 (22.4) | 67 (16.0) | 383 (20.9) | |
| Retired military | 280 (19.8) | 43 (10.3) | 323 (17.6) | |
| Infected during Delta periode | 111 (7.9) | 373 (89.0) | 484 (26.4) | <.001 |
| Fully vaccinated after SARS-CoV-2 infection | ||||
| No | 246 (17.4) | 419 (100.0) | 665 (36.3) | <.001 |
| Yes | 1167 (82.6) | 0 (0.0) | 1167 (63.7) | |
| Hospitalization status | ||||
| Hospitalized | 223 (15.8) | 13 (3.1) | 236 (12.9) | <.001 |
| Not hospitalized | 1190 (84.2) | 406 (96.9) | 1596 (87.1) | |
| Duration of hospitalization for COVID-19, median (IQR), d | 5.0 (3.0-8.0) | 3.5 (2.2-6.2) | 5.0 (3.0-8.0) | .15f |
| Maximum reported severity on survey | ||||
| Never had symptoms | 199 (14.1) | 18 (4.3) | 217 (11.8) | <.001 |
| Mild | 309 (21.9) | 72 (17.2) | 381 (20.8) | |
| Moderate | 534 (37.8) | 200 (47.7) | 734 (40.1) | |
| Severe | 336 (23.8) | 125 (29.8) | 461 (25.2) | |
| Critical | 35 (2.5) | 4 (1.0) | 39 (2.1) | |
| Reported recovery from COVID-19 | ||||
| No | 121 (8.6) | 23 (5.5) | 144 (7.9) | .04 |
| Yes | 1292 (91.4) | 396 (94.5) | 1688 (92.1) | |
| Duration of resolved illnesses | ||||
| Median (IQR), d | 16.0 (7.0-38.2) | 14.0 (5.0-28.2) | 15.0 (7.0-33.0) | <.001f |
| Missing data, No. | 121 | 23 | 144 | NA |
| Duration of ongoing illnesses, d | ||||
| Median (IQR) | 353.0 (219.0-375.0) | 276.0 (205.5-353.5) | 351.5 (218.8-372.0) | .04f |
| Missing data, No. | 1292 | 396 | 1688 | NA |
| Duration group, d | ||||
| <28 | 811 (57.4) | 293 (69.9) | 1104 (60.3) | <.001 |
| 28-89 | 289 (20.5) | 75 (17.9) | 364 (19.9) | |
| ≥90 | 313 (22.2) | 51 (12.2) | 364 (19.9) | |
| Any longer-term symptoms reportedg | ||||
| No | 1126 (79.7) | 353 (84.2) | 1479 (80.7) | .04 |
| Yes | 287 (20.3) | 66 (15.8) | 353 (19.3) | |
| Any moderate to severe longer-term symptoms reportedg | ||||
| No | 1184 (83.8) | 369 (88.1) | 1553 (84.8) | .03 |
| Yes | 229 (16.2) | 50 (11.9) | 279 (15.2) | |
| Reported respiratory symptoms on enrollment survey | ||||
| No | 902 (63.8) | 212 (50.6) | 1114 (60.8) | <.001 |
| Yes | 511 (36.2) | 207 (49.4) | 718 (39.2) | |
a
Statistical comparisons used the Pearson χ2 test, unless otherwise specified.
b
Ascertained by survey self-report and included in the analysis because racial and ethnic minorities have been shown to experience more severe short-term outcomes of SARS-CoV-2 infection.
c
Other race and ethnicity includes those reporting multiple races and ethnicities as well as Native American individuals.
d
Underweight or normal weight was defined as less than 25; overweight, 25 to 29; obesity, 30 to 34; and severe obesity, 35 or higher.
e
July 1 to December 31, 2021.
f
Kruskal-Wallis rank sum test.
g
Lasting more than 1 month.