COVID-19 symptoms at time of testing and association with positivity among outpatients tested for SARS-CoV-2

Abstract

Introduction: Symptoms associated with SARS-CoV-2 infection remain incompletely understood, especially among ambulatory, non-hospitalized individuals. With host factors, symptoms predictive of SARS-CoV-2 could be used to guide testing and intervention strategies.

Methods: Between March 16 and September 3, 2020, we examined the characteristics and symptoms reported by individuals presenting to a large outpatient testing program in the Southeastern US for nasopharyngeal SARS-CoV-2 RNA RT-PCR testing. Using self-reported symptoms, demographic characteristics, and exposure and travel histories, we identified the variables associated with testing positive using modified Poisson regression.

Results: Among 20,177 tested individuals, the proportion positive was 9.4% (95% CI, 9.0-9.8) and was higher for men, younger individuals, and racial/ethnic minorities (all P<0.05); the positivity proportion was higher for Hispanics (26.9%; 95% CI. 24.9-29.0) compared to Blacks (8.6%; 95% CI, 7.6-9.7) or Whites (5.8%; 95% CI, 5.4-6.3). Individuals reporting contact with a COVID-19 case had the highest positivity proportion (22.8%; 95% CI, 21.5-24.1). Among the subset of 8,522 symptomatic adults who presented for testing after May 1, when complete symptom assessments were performed, SARS-CoV-2 RNA PCR was detected in 1,116 (13.1%). Of the reported symptoms, loss of taste or smell was most strongly associated with SARS-CoV-2 RNA detection with an adjusted risk ratio of 3.88 (95% CI, 3.46-4.35). The presence of chills, fever, cough, aches, headache, fatigue and nasal congestion also significantly increased the risk of detecting SARS-CoV-2 RNA, while diarrhea or nausea/vomiting, although not uncommon, were significantly more common in those with a negative test result. Symptom combinations were frequent with 67.9% experiencing ≥4 symptoms, including 19.8% with ≥8 symptoms; report of greater than three symptoms increased the risk of SARS-CoV-2 RNA detection.

Conclusions: In a large outpatient population in the Southeastern US, several symptoms, most notably loss of taste or smell, and greater symptom burden were associated with detection of SARS-CoV-2 RNA. Persons of color and those with who were a contact of a COVID-19 case were also more likely to test positive. These findings suggest that, given limited SARS-CoV-2 testing capacity, symptom presentation and host characteristics can be used to guide testing and intervention prioritization.

Fig 1. SARS-CoV-2 testing and positivity proportion among 20,177 symptomatic and asymptomatic individuals, UNC RDC March 16 to September 3, 2020.

Number of individuals tested per day stratified by (A) SARS-CoV-2 positive result, (B) sex, (C) race/ethnicity and (D) age. Longitudinal SARS-CoV-2 positivity proportions (E) overall and stratified by (F) sex, (G) race/ethnicity and (H) age, with plotted centered sixth order polynomial regression and 95% confidence intervals. Abbreviations: UNC, University of North Carolina; RDC, Respiratory Diagnostic Center; No., number; SARS-CoV-2, severe acute respiratory coronavirus 2.

Fig 2. SARS-CoV-2 positivity by COVID-19 symptom among 8,522 symptomatic adults, UNC RDC May 1 to September 3, 2020.

(A) Percent of individuals reporting COVID-19 symptom and positivity proportion with 95% confidence interval for each COVID-19 symptom. (B) Unadjusted and adjusted risk ratios and 95% confidence intervals for testing positive for each COVID-19 symptom, with adjusted estimates adjusted for sex, age and race/ethnicity. The unadjusted and adjusted risk ratios for each symptom contrast the presence of that symptom with not having that symptom. Abbreviations: UNC, University of North Carolina; RDC, Respiratory Diagnostic Center; No., number; SARS-CoV-2, severe acute respiratory coronavirus 2; CI, Confidence Interval; SOB, shortness of breath.

Fig 3. COVID-19 symptoms among 1,116 symptomatic adults with positive SARS-CoV-2 RNA, UNC RDC May 1 to September 3, 2020.

(A and B) Percent of individuals with COVID-19 symptom by sex and age. (C and D) Box plots of number of symptoms by sex and age. (E and F) Percent of individuals with number symptoms with plotted centered sixth order polynomial regression, by sex and age. Abbreviations: UNC, University of North Carolina; RDC, Respiratory Diagnostic Center; No., number; SARS-CoV-2, severe acute respiratory coronavirus 2; SOB, shortness of breath.

Fig 4. COVID-19 symptom combinations among 1,116 symptomatic outpatient adults with positive SARS-CoV-2 RNA, UNC RDC May 1 to September 3, 2020.

(A) All symptom combinations reported by at least five individuals. (B) Percent reporting symptom combinations. (C) Phi correlation heat map for symptom combinations. (D) Percent reporting symptom category combinations. (E) Phi correlation heat map for symptom category combinations. Abbreviations: UNC, University of North Carolina; RDC, Respiratory Diagnostic Center; No., number; SARS-CoV-2, severe acute respiratory coronavirus 2; SOB, shortness of breath; URTI, upper respiratory tract infection; GI, gastrointestinal.