Anterior nasal versus nasal mid-turbinate sampling for a SARS-CoV-2 antigen-detecting rapid test: does localisation or professional collection matter?

ABSTRACT

ObjectivesThe aim of this diagnostic accuracy study was direct comparison of two different nasal sampling methods for an antigen-based rapid diagnostic test (Ag-RDT) that detects severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Furthermore, the accuracy and feasibility of self-sampling was evaluated. MethodsThis manufacturer-independent, prospective diagnostic accuracy study, compared professional anterior nasal (AN) and nasal mid-turbinate (NMT) sampling for a WHO-listed SARS-CoV-2 Ag-RDT. A second group of participants collected a NMT sample themselves and underwent a professional nasopharyngeal swab for comparison. The reference standard was real-time polymerase chain reaction (RT-PCR) using combined oro-/nasopharyngeal sampling. Individuals with high suspicion of SARS-CoV-2 infection were tested. Sensitivity, specificity, and percent agreement were calculated. Self-sampling was observed without intervention. Feasibility was evaluated by observer and participant questionnaires. ResultsAmong 132 symptomatic adults, both professional AN- and NMT-sampling yielded a sensitivity of 86.1% (31/36 RT-PCR positives detected; 95%CI 71.3-93.9) and a specificity of 100.0% (95%CI 95.7-100). The positive percent agreement (PPA) was 100% (95%CI 89.0-100). Among 96 additional adults, self NMT- and professional NP-sampling yielded an identical sensitivity of 91.2% (31/34; 95%CI 77.0-97.0). Specificity was 98.4% (95%CI 91.4-99.9) with NMT- and 100.0% (95%CI 94.2-100) with NP-sampling. The PPA was 96.8% (95%CI 83.8-99.8). Most participants (85.3%) considered self-sampling as easy to perform. ConclusionProfessional AN- and NMT-sampling are of equivalent accuracy for an Ag-RDT in ambulatory symptomatic adults. Participants were able to reliably perform the NMT-sampling themselves, following written and illustrated instructions. Nasal self-sampling will likely facilitate scaling of SARS-CoV-2 antigen testing.