text: SARS CoV 2 detection in nasopharyngeal swabs performance characteristics of a real time RT qPCR and a droplet digital RT PCR assay based on the exonuclease region ORF1b nsp 14 The emergence and spread of SARS CoV 2 has led to a compelling request for accurate diagnostic tests The aim of this study was assessing the performance of a real time RT qPCR rt RT qPCR assay and of a droplet digital RT PCR dd RT PCR targeting the nsp14 genome region for the detection of SARS CoV 2 in nasopharyngeal swabs A total of 258 nasopharyngeal swabs were analyzed with the nsp14 assays and for comparison with a reference assay targeting the RdRp and E genes Conflicting results were further investigated by two additional protocols the Centers for Disease Control and Prevention CDC real time targeting N1 N2 and a nested RT PCR for the spike region Agreement of results was achieved on 226 samples 156 positive and 70 negative 8 samples were positive in the reference assay and in the nsp14 rt RT qPCR but negative with the dd RT PCR and 24 samples provided different combinations of results with the three assays Sensitivity specificity and accuracy 95 C I of the nsp14 assays were 100 0 97 4 100 0 98 7 92 1 100 0 and 99 6 97 5 100 0 for the rt RT qPCR 92 4 87 4 95 6 100 0 94 2 100 0 and 94 7 91 1 97 0 for the dd RT PCR The results of the study support the use of the nsp14 real time RT qPCR and ddPCR for the detection of SARS CoV 2 in nasopharyngeal swabs 