2.1.3. Control samples

Known copies of 2019-nCoV_N positive control plasmids and Hs_RPP30 control containing human RNase P gene purchased from IDT were used as positive control and internal control, respectively. The main stock of the positive plasmid control for each targets contained 2lac copy/μl. The potency of each plasmid controls was checked by serially diluted solutions (2000, 200 and 20 copy/μl) using three replicates for each dilution. Finally, 200 copy/μl was used as positive control in the kit according to the general recommendation from IDT. These plasmid controls were directly added to the mastermix as templates. Samples were considered positive for SARS-CoV-2 infection when a signal was detected at Ct <38 and negative if the N-gene specific signals were undetermined or detected at Ct >38 along with the amplified RP signal of a Ct <40. A specimen was considered invalid when both N1/N2 signals and RP signal were undetermined. A no-template control (NTC) consisting of nuclease-free water was also used.