Sars cov 2 assay

The collected swabs (Heidelberg, IMPROSWAB, Improve; Berlin, eSwab, Copan) for routine RT-PCR testing were kept in provided Amies solution. The RT-PCR assays performed were Allplex SARS-CoV-2 Assay from Seegene (Seoul, South Korea) in Heidelberg and the Roche cobas SARS CoV-2 assay (Pleasanton, CA United States) on the cobas^® 6800 or 8800 system or the SARS CoV-2 assay from TibMolbiol (Berlin, Germany) in Berlin. Ct-values varied in a range of 2–3 between the three technologies. For the Ct-value presentation and the viral load calculations the E-Gene was used as reference Ct-value. A conversion of the Ct-values into viral-load was performed using quantified specific in vitro-transcribed RNA [14 ].

Reverse transcriptase-polymerase chain reaction (RT-PCR) was used as the reference test. The RT-PCR samples were collected by health-care workers using the IMPROSWAB^® (Guangzhou Improve Medical Instruments Co., Ltd., Guangzhou, China) at the Heidelberg study site and the eSwab™ (Copan Diagnostics Inc., Murrieta, CA, USA) at the study site in Berlin. Collected samples were transferred to the referral laboratories for RT-PCR testing in Heidelberg and Berlin. The RT-PCR assays, referral laboratory standard assays, used for clinical diagnosis as comparators were Allplex™ SARS-CoV-2 assay (Seegene, Seoul, South Korea) in Heidelberg and cobas™ SARS CoV-2 assay on the cobas^® 6800 or 8800 system (Roche, Pleasanton, CA, United States) or the SARS CoV-2 assay from TIB Molbiol (Berlin, Germany) in Berlin. Interpretation of the RT-PCR assays followed the manufacturers’ instructions. The RT-PCR assays targeted the E gene of SARS-CoV-2, which was used for the CT-value determination and the viral load calculations. Based on testing of standardized material, CT-values of the three tests are expected to differ by around 2–3 with the same amount of virus present [2 (link)]. The conversion of CT-values into viral-load was based on calibrated RT-PCR testing with quantified SARS-CoV-2 in vitro transcripts [2 (link)].