Table 4. Logistic regression results for odds ratio of testing seropositive for SARS-CoV-2, Orange County, California, USA, July–August 2020*.
| Characteristic | No. (%) |
Adjusted odds ratio (95% CI)† | |
|---|---|---|---|
| SARS-CoV-2 seropositive, n = 350 | Total tested, n = 2,604 | ||
| Age group, y | |||
| 18–24 | 19 (5.43) | 158 (5.35) | Referent |
| 25–29 | 31 (8.86) | 234 (7.92) | 1.09 (0.58–2.04) |
| 30–34 | 33 (9.43) | 275 (9.31) | 0.97 (0.52–1.81) |
| 35–39 | 35 (10) | 328 (11.1) | 0.85 (0.46–1.56) |
| 40–49 | 83 (23.71) | 651 (22.04) | 1.08 (0.62–1.87) |
| 50–59 | 82 (23.43) | 659 (22.31) | 1.09 (0.62–1.89) |
| 60–69 | 46 (13.14) | 418 (14.15) | 1.02 (0.56–1.86) |
| 70–79 | 18 (5.14) | 188 (6.36) | 0.93 (0.45–1.91) |
|
>80 |
3 (0.86) |
43 (1.46) |
0.64 (0.18–2.32) |
| Sex | |||
| F | 222 (63.43) | 1,668 (56.47) | Referent |
| M |
128 (36.57) |
1,286 (43.53) |
0.75 (0.59–0.94) |
| Race or ethnicity‡ | |||
| White | 108 (30.86) | 1,228 (41.57) | Referent |
| Asian | 47 (13.43) | 435 (14.73) | 1.25 (0.85–1.82) |
| Black | 5 (1.43) | 42 (1.42) | 1.28 (0.48–3.37) |
| Hispanic | 162 (46.29) | 1,010 (34.19) | 1.54 (1.17–2.03) |
| Pacific Islander | 3 (0.86) | 12 (0.41) | 3.89 (1.04–14.65) |
| Unknown |
25 (7.14) |
227 (7.68) |
1.25 (0.78–2) |
| % With college degree in ZIP code | |||
| 1st quartile | 158 (45.14) | 937 (31.72) | Referent |
| 2nd quartile | 92 (26.29) | 893 (30.23) | 0.98 (0.65–1.46) |
| 3rd quartile | 59 (16.86) | 644 (21.8) | 1.15 (0.64–2.04) |
| 4th quartile |
41 (11.71) |
480 (16.25) |
1.15 (0.59–2.22) |
| % With insurance in ZIP code | |||
| 1st quartile | 154 (44) | 928 (31.42) | Referent |
| 2nd quartile | 91 (26) | 812 (27.49) | 0.98 (0.67–1.43) |
| 3rd quartile | 54 (15.43) | 597 (20.21) | 0.99 (0.56–1.76) |
| 4th quartile |
51 (14.57) |
617 (20.89) |
0.95 (0.51–1.76) |
| Population density, × 1,000 persons/km2 | 1.02 (0.81–1.29) | ||
| House crowding index |
|
|
1.00 (0.96–1.04) |
| Median income (SD) | 0.76 (0.57–1.00) | ||
| % Persons in ZIP code SARS-CoV-2 positive >10%§ | 1.25 (0.80–1.96) | ||
*This cross sectional survey was conducted July 10–August 16, 2020. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2. †Model intercept represents odds of testing seropositive for SARS-CoV-2 for a White female diagnosed with SARS-CoV2 in the 18–24 years age group in a ZIP code in the first quartile of college degree and insured with the average population density, and average percentage of SARS-CoV-2 positive persons in Orange County. The odds of this person testing seropositive is estimated to be 0.074 (95% CI 0.031–0.178). 95% CIs computed with robust SEs. ‡For comparison, the estimated race/ethnicity makeup of Orange County in 2021 is non-Hispanic White (38.6%, n = 1,223,157; Black/African American (1.6%, n = 52,696); American Indian or Alaskan Native (0.3%, n = 6,018); Asian (21.1%, n = 685,728); Native Hawaiian or Pacific Islander (0.3%, n = 8,885); other or multiple races (3.1%, n = 100,297); Hispanic or Latinx (35.0%, n = 1,115,740) (21). American Indian or Alaska Native race group not included in analysis because of lack of data; no person of this race group tested seropositive. §Number of persons who tested positive in person’s ZIP code reported to Orange County Public Health Department during March 1–August 16, 2020, divided by estimated population of ZIP code.