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Table 2 Interpretation criteria for the results of the qq-PCR assay

From: Establishment and evaluation of a quadruple quantitative real-time PCR assay for simultaneous detection of human coronavirus subtypes

Ct value Result
FAM channel ROX channel Cy5 channel VIC channel
 ≥ 38.5/undetermined/no Ct  ≥ 38.5/undetermined/no Ct  ≥ 38.5/undetermined/no Ct  ≤ 38.5 Negative
 ≤ 38.5  ≤ 38.5  ≥ 38.5/undetermined/no Ct  ≤ 38.5 SARS-CoV-2
 ≥ 38.5/undetermined/no Ct  ≤ 38.5  ≥ 38.5/undetermined/no Ct  ≤ 38.5 Severe HCoVs (SARS-CoV-2 or SARS-CoV)
 ≥ 38.5/undetermined/no Ct  ≥ 38.5/undetermined/no Ct  ≤ 38.5  ≤ 38.5 Seasonal HCoVs
  1. Ct, cycle threshold; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; HCoVs, human coronavirus; SARS-CoV, severe acute respiratory syndrome coronavirus