A Comparison of Less Invasive SARS-CoV-2 Diagnostic Specimens in Nursing Home Residents — Arkansas, June–August 2020

Abstract

Abstract Background SARS-CoV-2 testing remains essential for early identification and clinical management of cases. We compared the diagnostic performance of three specimen types for characterizing SARS-CoV-2 in infected nursing home residents. Methods A convenience sample of 17 residents were enrolled within 15 days of first positive SARS-CoV-2 result by real-time reverse transcription polymerase chain reaction (RT-PCR) and prospectively followed for 42 days. Anterior nasal swabs (AN), oropharyngeal swabs (OP), and saliva specimens (SA) were collected on the day of enrollment, every 3 days for the first 21 days, then weekly for 21 days. Specimens were tested for presence of SARS-CoV-2 RNA using RT-PCR and replication-competent virus by viral culture. Results Comparing the three specimen types collected from each participant at each time point, the concordance of paired RT-PCR results ranged from 80–88%. After the first positive result, SA and OP were RT-PCR–positive for ≤48 days; AN were RT-PCR–positive for ≤33 days. AN had the highest percentage of RT-PCR–positive results (81%; 21/26) when collected ≤10 days of participants’ first positive result. Eleven specimens were positive by viral culture: nine AN collected ≤19 days following first positive result and two OP collected ≤5 days following first positive result. Conclusions AN, OP, and SA were effective methods for repeated testing in this population. More AN than OP were positive by viral culture. SA and OP remained RT-PCR–positive longer than AN, which could lead to unnecessary interventions if RT-PCR detection occurred after viral shedding has likely ceased.