Coinfections with Respiratory Pathogens among COVID-19 Patients in Korea

Figure 2

Ct values of the E, RdRP, and N genes in the Allplex 2019-nCoV assay for SARS-CoV-2 performed on nucleic acids extracted from the NPS/OPS and sputum specimens collected from the study group (N = 342). (a) Ct values of the E, RdRP, and N genes detected in NPS/OPS (N = 330) and sputum (N = 167) specimens among all study subjects (N = 342). (b) Ct values among the study subjects (N = 155) who were classified as positive for SARS-CoV-2 in both NPS/OPS and sputum samples. (c) Ct values among the study subjects (N = 26) who were classified as positive for SARS-CoV-2 in NPS/OPS but negative in sputum (NPS/OPS + but sputum −) and the subjects (N = 12) classified as negative for SARS-CoV-2 in NPS/OPS but positive in sputum (NPS/OPS – but sputum +). (d) Ct values among the study subjects (N = 149) who were classified as positive for SARS-CoV-2 in NPS/OPS even though their sputum specimens were not submitted. Ct: cycle threshold; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; NPS: nasopharyngeal swab; OPS: oropharyngeal swab; E: envelope protein gene; RdRP: RNA-dependent RNA polymerase gene; N: nucleocapsid protein gene. Significant difference; differences in Ct values of the E, RdRP, and N genes between those who were SARS-CoV-2 positive in tests on the NPS/OPS specimens but negative in tests on sputum (N = 26) and those who were negative in tests on their NPS/OPS specimens but positive in tests on their sputum (N = 12) were 8.2, 7.8, and 7.4, respectively, which were significantly different ().

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