Comparison of self-collected oral-nasal and mid-turbinate swabs to healthcare worker-collected nasopharyngeal swabs for the detection of SARS-CoV-2: a paired clinical evaluation.

Abstract

Accurate detection of respiratory viruses is essential for infection control, patient management and public health response. Nasopharyngeal swabs (NPS), collected by healthcare workers (HWC-NPS), remain the gold standard for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) detection but require trained personnel and can be uncomfortable for patients. Self-collected swabs, such as oral-nasal swabs (SC-ONS) and mid-turbinate swabs, offer scalable alternatives suitable for mass testing. Previous mid-turbinate swab designs included a plastic stopper and were not compatible with automated laboratory testing. This study compared the performance of (i) SC-ONS, (ii) an automation-friendly, redesigned version of mid-turbinate swab (SC-MTS) and (iii) HWC-NPS in detecting SARS-CoV-2. Between April and June 2022, paired NPS, ONS and MTS samples were collected from 100 participants at a Coronavirus disease 2019 (COVID-19) assessment centre in Hamilton, Ontario. Samples were tested for SARS-CoV-2 by reverse-transcriptase PCR. Compared to HWC-NPS, SC-ONS demonstrated 82.1% sensitivity and 100% specificity, while SC-MTS showed 75.0% sensitivity and 100% specificity. Agreement with HWC-NPS was strong for both SC-ONS (κ=0.863) and SC-MTS (κ=0.804). Agreement between SC-ONS and SC-MTS was nearly perfect (κ=0.944). Cellular material yields as well as SARS-CoV-2 viral loads were lower for self-collected swabs than HWC-NPS, while viral load comparisons revealed no significant difference between SC-ONS and SC-MTS. Our study aligns with previous work demonstrating the use of self-collected mid-turbinate swabs for the detection of respiratory viruses, while also demonstrating the compatibility of the newly designed swabs with automated laboratory instruments. Our results, while conducted in a relatively small sample, suggest that self-collected ONS and MTS are reliable alternatives to HWC-NPS, offering practical, less invasive, automation-friendly options for large-scale respiratory virus surveillance and pandemic preparedness.