Clinical characteristics and viral load dynamics of COVID-19 in a mildly or moderately symptomatic outpatient sample.

BACKGROUND: Studies of outpatients with mild or moderate COVID-19 are uncommon. We studied: 1) association of symptoms with reverse transcriptase polymerase chain reaction (RT-PCR) test results; and 2) association of initial RT-PCR cycle threshold (Ct) in relation to duration of RT-PCR positivity in outpatients with mild or moderate COVID-19. METHODS: This was a cohort study of outpatients with confirmed COVID-19 and at least one symptom. Participants had repeat nasopharyngeal swabs and symptom checklists every 3-5 days until two consecutive RT-PCR tests were negative. RT-PCR tests were used to assess viral load. Antibody tests for COVID-19 were performed at 2 weeks, 4 weeks, and 8 weeks after symptom onset. RESULTS: Twenty-five patients (nine females) were enrolled, ranging in age from 19-58 (median age 28 years). All patients reported at least one symptom, with a median of six symptoms per patient. Symptoms persisted for 6-67 days (median duration 18 days). In all 25 patients, blood samples collected a median of 13 days after symptom onset were positive for SARS-CoV-2 antibodies in 15 (60%). After a median of 28 days following symptom onset, 23/23 patients with available samples tested positive for antibodies. The longest duration of positive RT-PCR test was 49 days from first positive PCR test (Mean = 27.4, SD = 12.5, Median = 24). Initial Ct was significantly associated with longer duration (ß = -1.3, SE = 0.3, p<0.01 per 1 cycle higher) of RT-PCR positivity. CONCLUSIONS: In mildly or moderately ill COVID-19 outpatients, RT-PCT tests remained positive for as long as 49 days and test positivity and symptom duration correlated with initial viral load.

Whom Should We Test for COVID-19? Performance of a Symptom and Risk Factor Questionnaire on COVID-19 Test Results and Patient Outcomes in an Immediate Care Setting.

INTRODUCTION: The CDC and Illinois Department of Public Health disseminated risk factor criteria for COVID-19 testing early in the pandemic. The objective of this study is to assess the effectiveness of risk stratifying patients for COVID-19 testing and to identify which risk factors and which other clinical variables were associated with SARS-CoV-2 PCR test positivity. METHODS: We conducted an observational cohort study on a sample of symptomatic patients evaluated at an immediate care setting. A risk assessment questionnaire was administered to every patient before clinician evaluation. High-risk patients received SARS-CoV-2 test and low-risk patients were evaluated by a clinician and selectively tested based on clinician judgment. Multivariate analyses tested whether risk factors and additional variables were associated with test positivity. RESULTS: The adjusted odds ratio of testing positive was associated with COVID-19-positive or suspect close contact (aOR 1.56, 95% CI 1.15-2.10), large gathering attendance with a COVID-19-positive individual (aOR 1.92, 95% CI 1.10-3.34), and, with the largest effect size, decreased taste/smell (aOR 2.83, 95% CI 2.01-3.99). Testing positive was associated with ages 45-64 and ≥65 (aOR 1.75, 95% CI 1.25-2.44, and aOR 2.78, 95% CI 1.49-5.16), systolic blood pressures ≤120 (aOR 1.64, 95% CI 1.20-2.24), and, with the largest effect size, temperatures ≥99.0°F (aOR 3.06, 95% CI 2.23-4.20). The rate of positive SARS-CoV-2 test was similar between high-risk and low risk patients (225 [22.2%] vs 50 [19.8%]; P = .41). DISCUSSION: The risk assessment questionnaire was not effective at stratifying patients for testing. Although individual risk factors were associated with SARS-CoV-2 test positivity, the low-risk group had similar positivity rates to the high-risk group. Our observations underscore the need for clinicians to develop clinical experience and share best practices and for systems and payors to support policies, funding, and resources to test all symptomatic patients.