Sample and Data Analysis
Seventy-five (75) frozen archived nasopharyngeal samples – consisting
of 38 positive and 37 negative rRT- PCR tested COVID-19 samples were
obtained for the evaluation of the three (3) brands of the
immunochromatographic RDT kits. The archived samples were selected using
a flow chart (supplementary figure 1, SF1 ). It is worth
noting that these samples were retested using rRT-PCR (the
reference test, S0 ) prior to the immunochromatographic assays
(the index test, S1 ). The three immunochromatographic
antigen kits (i.e., DG Rapid, SD Rapid, and SS Rapid) consist of
qualitative membrane-based immunoassays and detect SARS-CoV-2
nucleocapsid antigen. All assays were performed by a single operator for
each brand of test kit, with two blind operators reading the results. In
case of discrepancies, a third operator was consulted, especially for
faint test lines. All tests were performed according to the
manufacturer’s instructions (10–12). The results generated were entered
into Microsoft Excel-365 and analyzed using IBM SPSS Statistics version
23. A Flow chart of the method from sample selection to
data analysis can be found in supplementary figure 1 (SF1)
Results