Performance of and Severe Acute Respiratory Syndrome Coronavirus 2 Diagnostics Based on Symptom Onset and Close Contact Exposure: An Analysis From the Test Us at Home Prospective Cohort Study

• Published in: Open forum infectious diseases 2024-06, Vol.11 (6), p.ofae304
• Main Authors: Herbert, Carly, Wang, Biqi, Lin, Honghuang, Yan, Yi, Hafer, Nathaniel, Pretz, Caitlin, Stamegna, Pamela, Wright, Colton, Suvarna, Thejas, Harman, Emma, Schrader, Summer, Nowak, Chris, Kheterpal, Vik, Orvek, Elizabeth, Wong, Steven, Zai, Adrian, Barton, Bruce, Gerber, Ben S, Lemon, Stephenie C, Filippaios, Andreas, Gibson, Laura, Greene, Sharone, Colubri, Andres, Achenbach, Chad, Murphy, Robert, Heetderks, William, Manabe, Yukari C, O'Connor, Laurel, Fahey, Nisha, Luzuriaga, Katherine, Broach, John, Roth, Kristian, McManus, David D, Soni, Apurv
• Format: Article
• Language: English
• Subjects: Diagnostic Methods and Tools
• ISSN: 2328-8957; 2328-8957
• DOI: 10.1093/ofid/ofae304

Understanding changes in diagnostic performance after symptom onset and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure within different populations is crucial to guide the use of diagnostics for SARS-CoV-2. The Test Us at Home study was a longitudinal cohort study that enrolled individuals across the United States between October 2021 and February 2022. Participants performed paired antigen-detection rapid diagnostic tests (Ag-RDTs) and reverse-transcriptase polymerase chain reaction (RT-PCR) tests at home every 48 hours for 15 days and self-reported symptoms and known coronavirus disease 2019 exposures immediately before testing. The percent positivity for Ag-RDTs and RT-PCR tests was calculated each day after symptom onset and exposure and stratified by vaccination status, variant, age category, and sex. The highest percent positivity occurred 2 days after symptom onset (RT-PCR, 91.2%; Ag-RDT, 71.1%) and 6 days after exposure (RT-PCR, 91.8%; Ag-RDT, 86.2%). RT-PCR and Ag-RDT performance did not differ by vaccination status, variant, age category, or sex. The percent positivity for Ag-RDTs was lower among exposed, asymptomatic than among symptomatic individuals (37.5% (95% confidence interval [CI], 13.7%-69.4%) vs 90.3% (75.1%-96.7%). Cumulatively, Ag-RDTs detected 84.9% (95% CI, 78.2%-89.8%) of infections within 4 days of symptom onset. For exposed participants, Ag-RDTs detected 94.0% (95% CI, 86.7%-97.4%) of RT-PCR-confirmed infections within 6 days of exposure. The percent positivity for Ag-RDTs and RT-PCR tests was highest 2 days after symptom onset and 6 days after exposure, and performance increased with serial testing. The percent positivity of Ag-RDTs was lowest among asymptomatic individuals but did not differ by sex, variant, vaccination status, or age category.