Diagnostic values analysis of SARS-CoV-2 antibodies using Mindray CL-900i at Dr. Soetomo Hospital Surabaya

Background: rRT-PCR is one of the definitive diagnostic tests for COVID-19 infection. The antibody (serological) assay is another method used to diagnose COVID-19 infection. This assay is quick and easy to perform, but it needs a high level of sensitivity and specificity. The objective of this research is to analyse the diagnostic values of SARS-CoV-2 IgM and IgG antibodies produced by patients with confirmed COVID-19 infection using the Mindray CL-900i. Methods: This study design was an analytic observational study using a cross-sectional design with a diagnostic test approach. rRT-PCR-confirmed COVID-19 infection patients' serum samples were collected between day one and day twenty-one following the onset of symptoms. The positive sample population was divided into three groups: days 1-7 of illness, days 8-14 of illness and days 15-21 days of illness. Anti-SARS-CoV-2 IgM and IgG levels in each sample were evaluated using Mindray CL-900i to determine positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity utilising a Mindray CL-900i. Results: The anti-SARS-CoV-2 IgM serological assays using Mindray CL-900i showed that IgM has 89.09% sensitivity, 88.57% specificity, 92.45% PPV, and 83.78% NPV. The sensitivity of IgM serology examinations was 87.09% in the days 1-7 of the illness group, 100% in the days 8-14 of the illness group, and 85.71% in the days 15-21 of illness group. Meanwhile, the anti-SARS-CoV-2 IgG serological assays using Mindray CL-900i showed that IgG had 88.9% sensitivity, 94.4% specificity, 96% PPV, and 85% NPV. The sensitivity of IgG serology examinations was 80.64% in the days 1-7 of the illness group, 100% in the days 8-14 of the illness group, and 100% in the days 15-21 of the illness group. Antibodies were detected on days 0-7 following the initiation of symptoms; anti-SARS-CoV-2 IgM demonstrated a higher rate of sensitivity compared to anti-SARS-CoV-2 IgG. The sensitivity of anti-SARS-CoV-2 IgG increased and stayed higher than that of anti-SARS-CoV-2 IgM starting on the eighth day after the onset of symptoms. Detectable IgG was found in the group from the first week of illness; this could be the result of a cross-reaction with previous infections with corona viruses other than SARS-CoV2. Conclusion: Anti-SARS-CoV-2 IgM and IgG serological assays using Mindray CL-900i were found to be sensitive and specific for diagnosing patients with probable COVID-19 infection.