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Table 1 The sensitivity and specificity of direct RT-qPCR on self-collected nasal swabs in samples with clear SARS-CoV-2 positivity (Ct < 37) detected by two-step RT-qPCR on nasopharyngeal swabs

From: Excellent option for mass testing during the SARS-CoV-2 pandemic: painless self-collection and direct RT-qPCR

  Two-step RT-qPCR on nasopharyngeal swabs
Positive# Negative Total
Direct RT-qPCR on nasal swab    
Positive 246 3* 249
Negative 13 776 789
Total 259 779 1038
Sensitivity 94.98% (95% CI 91.57–97.30%)   
Specificity 99.61% (95% CI 98.88–99.92%)   
Positive predictive value (PPV) 98.80% (95% CI 96.36–99.61%)   
Negative predictive value (NPV) 98.73% (95% CI 97.23–99.02%)   
  1. #RT-qPCR positivity is defined as having Ct values lower than or equal to 37
  2. *Direct RT-qPCR positivity for these nasal-swab samples was confirmed by two-step RT-qPCR from RNA isolates