Abstract
Introduction: Compared to nasopharyngeal swabs (NPS), there has been insufficient evaluation of the diagnostic performance of nasal swabs (NS) for the detection of severe acute respiratory coronavirus 2 (SARS-CoV-2) in the nucleic acid amplification test (NAAT) and quantitative SARS-CoV-2 antigen test (QAT).
Methods: We prospectively compared healthcare worker-collected and flocked NS within nine days after symptom onset to paired NPS to detect SARS-CoV-2 in NAAT and QAT on the fully automated Lumipulse system. The agreement between sample types was evaluated, and cycle threshold (Ct) values and antigen levels were used as surrogate viral load measures.
Results: Sixty sets of NPS and NS samples were collected from 40 patients with COVID-19. The overall agreements between NAAT and QAT samples were 76.7% and 65.0%, respectively. In NAAT, the Ct value of NS was significantly higher, 5.9, than that of NPS. Thirty-nine (95.1%) NS tested positive in 41 positive-paired NPS with Ct ≤ 30. The negative correlation was observed between antigen levels of NS in QAT and Ct values of NS in NAAT (r = -0.88). In QAT, the antigen level of NS was significantly lower than that of NPS. Thirty-six (90.0%) NS tested positive in 40 positive-paired NPS with antigen levels >100 pg/mL, which were collected significantly earlier than those with antigen levels ≤100 pg/mL.
Conclusions: In NAAT and QAT, NS had limited performance in detecting SARS-CoV-2 compared to NPS. However, NS may be helpful for patients with COVID-19 with high viral loads or those in the early stages of the illness.
Keywords: Nasal swabs; Nasopharyngeal swabs; Nucleic acid amplification test; Quantitative SARS-CoV-2 antigen test; SARS-CoV-2; Viral load.
【저자키워드】 SARS-CoV-2, nasopharyngeal swabs, nucleic acid amplification test, Viral load., nasal swabs, Quantitative SARS-CoV-2 antigen test, 【초록키워드】 diagnostic, Antigen, Nasopharyngeal swab, amplification, Measures, Viral load, cycle threshold, NAAT, healthcare, automated, SARS-CoV-2 antigen, nasal swab, nucleic acid amplification, Quantitative, early stage, symptom onset, negative correlation, positive, significantly lower, NPs, Respiratory Coronavirus, tested, detect, collected, significantly, evaluated, nine, were used, significantly higher, patients with COVID-19, 【제목키워드】 diagnostic, Antigen, SARS-CoV-2 detection, nasal swab, nucleic acid amplification, Quantitative,