Clinical Performance of SARS-CoV-2 Molecular Tests

• Published in: Journal of clinical microbiology Vol. 58; no. 8
• Main Authors: Green, Daniel A, Zucker, Jason, Westblade, Lars F, Whittier, Susan, Rennert, Hanna, Velu, Priya, Craney, Arryn, Cushing, Melissa, Liu, Dakai, Sobieszczyk, Magdalena E, Boehme, Amelia K, Sepulveda, Jorge L
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 23-07-2020
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Betacoronavirus - genetics; Betacoronavirus - isolation & purification; Child; Child, Preschool; Clinical Laboratory Techniques - methods; Coronavirus Infections - diagnosis; Coronavirus Infections - pathology; Coronavirus Infections - virology; COVID-19; COVID-19 Testing; Diagnostic Tests, Routine - methods; Female; Humans; Infant; Infant, Newborn; Male; Middle Aged; New York; Pandemics; Pneumonia, Viral - diagnosis; Pneumonia, Viral - pathology; Pneumonia, Viral - virology; Predictive Value of Tests; SARS-CoV-2; Sensitivity and Specificity; Special Issue; Viral Load; Virology; Young Adult; New York; COVID-19; SARS-CoV-2; sensitivity; negative predictive value; laboratory utilization
• ISSN: 0095-1137; 1098-660X
• DOI: 10.1128/JCM.00995-20

Molecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the gold standard for diagnosis of coronavirus disease 2019 (COVID-19), but the clinical performance of these tests is still poorly understood, particularly with regard to disease course, patient-specific factors, and viral shedding. From 10 March to 1 May 2020, NewYork-Presbyterian laboratories performed 27,377 SARS-CoV-2 molecular assays from 22,338 patients. Repeat testing was performed for 3,432 patients, of which 2,413 had initial negative and 802 had initial positive results. Repeat-tested patients were more likely to have severe disease and low viral loads. The negative predictive value of the first-day result among repeat-tested patients was 81.3% The clinical sensitivity of SARS-CoV-2 molecular assays was estimated between 58% and 96%, depending on the unknown number of false-negative results in single-tested patients. Conversion to negative was unlikely to occur before 15 to 20 days after initial testing or 20 to 30 days after the onset of symptoms, with 50% conversion occurring at 28 days after initial testing. Conversion from first-day negative to positive results increased linearly with each day of testing, reaching 25% probability in 20 days. Sixty patients fluctuated between positive and negative results over several weeks, suggesting that caution is needed when single-test results are acted upon. In summary, our study provides estimates of the clinical performance of SARS-CoV-2 molecular assays and suggests time frames for appropriate repeat testing, namely, 15 to 20 days after a positive test and the same day or next 2 days after a negative test for patients with high suspicion for COVID-19.