Supplementary Material for: Rapid Serological Tests for SARS-CoV-2: Diagnostic Performance of 4 Commercial Assays

<b><i>Objective:</i></b> To assess the diagnostic performance of lateral flow immunochromatographic assays (LFAs) of 4 different manufacturers to identify SARS-CoV-2 antibodies (IgM, IgG, or total), comparing them with the nucleic acid amplification test (NAAT) or the clinical defined test (definite or probable SARS-CoV-2 infection, respectively). <b><i>Methods:</i></b> One hundred nineteen serum samples were randomly selected by convenience and distributed in the following groups: (1) group with SARS-CoV-2 infection (<i>n</i> = 82; RT-qPCR positive [definite, <i>n</i> = 70] and probable [<i>n</i> = 12]); (2) other diseases (<i>n</i> = 27; other viruses identified [<i>n</i> = 8] and SARS of other etiologies [<i>n</i> = 19]); and (3) healthy control group (<i>n</i> = 10). LFAs of 4 manufacturers were compared: MedTest Coronavirus (COVID-19) IgG/IgM (MedLevensohn, Brazil); COVID-19 IgG/IgM ECO Test (Ecodiagnóstica, Brazil); Camtech COVID-19 IgM/IgG Rapid Test Kit (Camtech Diagnostics Pte Ltd, Singapore); and 1-Step COVID-19 Test for total antibodies (Guangzhou Wondfo Biotech Co., China). <b><i>Results:</i></b> The 4 tests studied showed high diagnostic performance characteristics for the diagnoses of definite or probable SARS-CoV-2 infection. The best measures were for the Wondfo test: sensitivity (86.59%; 95% CI: 77.26–93.11%), specificity (100%; 90.51–100%), DOR (257; 60–1,008), LR+ (33.43; 4.82–231.85), LR− (0.13; 0.08–0.23), accuracy (90.76%; 84.06–95.29%), and Matthews correlation coefficient (MCC) 0.82. Although considering only the probable SARS-CoV-2 infection (PCR−) cases, all the kits studied showed limited values. <b><i>Conclusion:</i></b> Our data demonstrate the excellent performance of LFA for the diagnoses of definite or probable SARS-CoV-2 infection. There was substantial heterogeneity in sensitivities of IgM and IgG antibodies among the different kits. LFA tests cannot replace molecular diagnostics but should be used as an additional screening tool.