SARS-CoV-2 viral load
Quantitative detection of SARS-CoV-2 RNA from the nasal wash of all the
clinical samples was done by performing rtRT-PCR using Simplexa™
COVID-19 Direct kit (DiaSorin) as per the manufacturer’s instructions.
Reactions were run on the LIAISON® MDX instrument (DiaSorin). The
DiaSorin Molecular Simplexa™ COVID-19 Direct assay system is a real-time
RT-PCR system that enables the direct amplification of Coronavirus
SARS-CoV-2 RNA from nasal wash (NW) specimen. The data is analyzed with
LIAISON® MDX Studio Software. The assay targets two different regions of
the SARS-CoV-2 genome, ORF1ab S gene14. The sample was
considered SARS-CoV-2 positive when one of the target genes in the same
sample was positive and negative if both the genes were negative. The Ct
values for both the genes were nearly similar. In this study, we used
the Ct value of ORF1ab from nasal wash for the comparisons. The Ct value
is inversely correlated with RNA copy number of the virus. Ct value
< 40 was considered COVID-19 positive.