Table 4.
Seroprevalence estimates among people with or without the characteristic and difference in seroprevalence, as assessed through a community survey of SARS-CoV-2 seroprevalence, Denver County, Colorado, July–August 2020
| Characteristic | Seroprevalence among those with characteristic, % (95% CI) | Seroprevalence among those without characteristic, % (95% CI) | Percentage-point difference in seroprevalence (95% CI) |
|---|---|---|---|
| Acute illness a | |||
| CSTE clinical criteria | 22.9 (10.2-43.8) | 4.6 (2.0-10.3) | 18.3 (1.8 to 34.8) |
| Fever, cough, or loss of smell or taste | 28.2 (12.8-51.2) | 4.4 (1.9-10.0) | 23.8 (4.0 to 43.6) |
| Any loss of smell or taste | 36.4 (13.9-67.1) | 5.2 (2.7-9.9) | 31.3 (−4.5 to 67.0) |
| Acute illness and tested | 37.5 (13.0-70.1) | 6.1 (3.1-11.4) | 31.4 (−4.1 to 67.0) |
| Compatible illness (CSTE COVID-19 clinical), not tested but asked to isolate | 86.4 (51.8-97.4) | 6.3 (2.7-14.2) | 80.1 (54.0 to 100.0) |
| RT-PCR testing | |||
| Ever tested by RT-PCR | 19.0 (6.1-46.0) | 5.3 (2.6-10.5) | 13.7 (−7.1 to 34.6) |
| RT-PCR positive | 85.1 (45.2-97.5) | 7.1 (3.3-14.6) | 78.0 (39.2 to 100.0) |
| RT-PCR positive when ill | 100.0 | 7.0 (3.2-14.5) | 93.0 (87.5 to 98.4) |
| Exposure history b | |||
| Close contact: RT-PCR–positive person | 53.9 (25.4-80.1) | 3.4 (1.8-6.3) | 50.5 (16.6 to 84.4) |
| RT-PCR–positive person: household member/partner | 94.1 (50.3-99.6) | 3.4 (1.8-6.3) | 90.7 (73.2 to 100.0) |
| RT-PCR–positive person: other | 33.6 (13.8-61.7) | 3.4 (1.8-6.3) | 30.2 (1.6 to 58.9) |
| Occupational characteristics c | |||
| Worked outside the home | 6.2 (3.5-10.8) | 8.1 (2.6-22.8) | −1.9 (−11.5 to 7.7) |
| Worked or volunteered in health care setting | 3.8 (1.0-13.4) | 7.1 (3.7-13.1) | −3.3 (−10.4 to 3.7) |
| Residential setting | |||
| Currently living in single-family home | 5.2 (1.3-18.9) | 10.2 (5.1-19.3) | −5.0 (−14.9 to 4.9) |
Abbreviations: CSTE, Council of State and Territorial Epidemiologists; RT-PCR, reverse transcription–polymerase chain reaction.
First 3 categories refer to illnesses with onset on March 1, 2020, or later; others reflect illness onset on January 15, 2020, or later. Excludes 4 illnesses with non–COVID-19 diagnosis (eg, myocardial infarction). CSTE clinical criteria reflect an illness meeting the clinical criteria of CSTE COVID-19 surveillance case definition 17 : (1) any 1 of the following: cough, shortness of breath, difficulty breathing, new olfactory disorder, new taste disorder (note: only loss of smell or taste was used in the survey) or (2) at least 2 of the following: fever (measured or subjective), chills, rigors, myalgia, headache, sore throat, nausea or vomiting, diarrhea, fatigue, or congestion/runny nose. Any loss of smell or taste includes data only from people aged ≥14 years.
Close contact with RT-PCR–positive person and the 2 exclusive subsets: questionnaire queried close contact with someone who received a positive test result while that contact was ill (first 10 days of illness) or around the time the testing was performed (2 days before to 10 days after swab). For health care workers, any patient contact lacking 6 feet of separation was considered close contact. For all others, close contact was defined as within 6 feet for 15 minutes or more or direct physical contact.
Occupational and volunteer history reflects adults only.