Diagnosed and Undiagnosed COVID-19 in US Emergency Department Health Care Personnel: A Cross-sectional Analysis

Abstract

Study objective: We determine the percentage of diagnosed and undiagnosed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among a sample of US emergency department (ED) health care personnel before July 2020.

Methods: This was a cross-sectional analysis of ED health care personnel in 20 geographically diverse university-affiliated EDs from May 13, to July 8, 2020, including case counts of prior laboratory-confirmed coronavirus disease 2019 (COVID-19) diagnoses among all ED health care personnel, and then point-in-time serology (with confirmatory testing) and reverse transcriptase-polymerase chain reaction testing in a sample of volunteers without a previous COVID-19 diagnosis. Health care staff were categorized as clinical (physicians, advanced practice providers, and nurses) and nonclinical (clerks, social workers, and case managers). Previously undiagnosed infection was based on positive SARS-CoV-2 serology or reverse transcriptase-polymerase chain reaction result among health care personnel without prior diagnosis.

Results: Diagnosed COVID-19 occurred in 2.8% of health care personnel (193/6,788), and the prevalence was similar for nonclinical and clinical staff (3.8% versus 2.7%; odds ratio 1.5; 95% confidence interval 0.7 to 3.2). Among 1,606 health care personnel without previously diagnosed COVID-19, 29 (1.8%) had evidence of current or past SARS-CoV-2 infection. Most (62%; 18/29) who were seropositive did not think they had been infected, 76% (19/25) recalled COVID-19-compatible symptoms, and 89% (17/19) continued to work while symptomatic. Accounting for both diagnosed and undiagnosed infections, 4.6% (95% confidence interval 2.8% to 7.5%) of ED health care personnel were estimated to have been infected with SARS-CoV-2, with 38% of those infections undiagnosed.

Conclusion: In late spring and early summer 2020, the estimated prevalence of severe acute respiratory syndrome coronavirus 2 infection was 4.6%, and greater than one third of infections were undiagnosed. Undiagnosed SARS-CoV-2 infection may pose substantial risk for transmission to other staff and patients.

Figure

Prevalence of diagnosed and estimated undiagnosed SARS-CoV-2 infections in US ED health care personnel, July 2020, by site. A, The percentage of health care personnel with diagnosed and undiagnosed infections in a sample of 20 US EDs at enrollment (May 13 to July 8, 2020). Gray bars represent the percentage of diagnosed infections as recorded in occupational health reports at the beginning of the enrollment period. Black bars represent undiagnosed infections estimated from a sample of previously undiagnosed disease in volunteer health care personnel in whom serology and nasal reverse transcriptase–PCR testing was performed (Table 2). White bars show the cumulative community COVID-19 incidence (June 29, 2020; right vertical axis). In total, 38% of all infections among ED health care personnel were undiagnosed before surveillance PCR and serology testing. B, The relationship between the percentage of recognized and estimated unrecognized infections in this sample, stratified by job classification. Gray bars represent diagnosed infections, and black bars represent undiagnosed ones.