Comparison of two SARS-CoV-2 RT-PCR assays and implication of the instrument software on cycle threshold (Ct) value.

The Cycle Threshold (Ct) value of SARS-CoV-2 RT-PCR are used as an indicator of viral load. Using a collection of 45 fresh nasopharyngeal samples collected on universal transport media, we compare the Ct value obtained with 2 RT-PCR assays, the Alinity M SARS-CoV-2 and the Alinity M RESP-4-Plex (Abbott Molecular, Des Plaines, Illinois, Etats-Unis) processed on an Alinity M device. The assays are highly correlated; however, the Ct values were in median lower of 4.