Association of Seroconversion Status with Outcome in Admitted Covid-19 Patients.

OBJECTIVE: To determine the association between seroconversion status and outcome in admitted COVID-19 patients and compare inflammatory markers amongst them. STUDY DESIGN: Single cohort observational study. PLACE AND DURATION OF STUDY: Indus Hospital and Health Network between 10th May and 10th July 2020. METHODOLOGY: All admitted patients were tested serially for anti-COVID-IgM and IgG until their sera showed positive results. This was continued until their expiry or discharge. Those patients who remained negative for both anti-COVID-19-IgG and IgM were labeled as non-seroconverts. Demographics, comorbidities, inflammatory marker levels and outcome (alive/expired) were compared between seroconverts and non-seroconverts. RESULTS: In 224 admitted patients, the median seroconversion time of IgM and IgG was six and seven days in survivors and non-survivors respectively. Expired patients displayed higher levels of procalcitonin (maximum), C-reactive protein, and Interleukin-6 (baseline and maximum). Of 34 non-seroconverts, 17 (50%) expired. Non-seroconverts significantly failed to develop fever and had lower levels of ferritin, CRP, and LDH. CONCLUSION: Non-seroconversion in hospitalised COVID-19 infected patients indicated muted immune and acute phase response and was associated with poor outcomes. Hence these patients need to be carefully evaluated and managed. KEY WORDS: Antibody response, Corticosteroids, Immunosuppression, SARS-Cov-2, Seroconversion.

Sensitivity and Specificity of Anti-SARS-CoV-2 Detection Kits - Comparison and Agreement between Fifteen Different Assays.

Accurate and rapid diagnosis of coronavirus disease 2019 (COVID-19) is critical for proper care and identification of affected individuals. This led to early availability of many serological assays in the market, but with limited validation. In this study, we aimed to validate the serological assays based on different techniques. We evaluated 15 different assays based on four immunoassay techniques in 235 patients. The most sensitive kits employed were as follows: immunochromatography (Zybio severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] IgM/IgG Antibody Assay Kit - 83%), ELISA (Aeskulisa SARS-CoV-2 NP IgG -88.1%), chemiluminescence (Alinity SARS-CoV-2 IgG - 82.2%), and immunofluorescence (Lifotronic FA160 (Shenzhen SARS-CoV-2 Assay Kit [IgG]) - 88.9%). The kits by Uniper (Singuway Biotec COVID-19 IgM/IgG Presumptive Kit), Genrui 2019-nCoV IgM/IgG Test Kit, Wondfu SARS-CoV-2 Antibody Test, and Aeskulisa SARS-CoV-2 NP IgG exhibited 100% specificity, whereas IgG assay using Lifotronic FA160 (Shenzhen SARS-CoV-2 Assay Kit) exhibited the lowest specificity at 58%. Maximum agreement was observed between Aeskulisa SARS-CoV-2 NP IgG and Alinity SARS-CoV-2 IgG at 94%. Serological tests are practical alternatives, but their reliability depends on critical validation. The COVID-19 pandemic warranted investment in healthcare research at both the national and international levels.