Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology
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Severe acute respiratory coronavirus 2 (SARS-CoV-2) has spread and caused death worldwide. Preventive measures and infection control are underway, and some areas show signs of convergence. Other viruses in addition to SARS-CoV-2 cause cold-like symptoms and spread in the winter. However, the extent to which SARS-CoV-2, influenza viruses and other causative viruses have prevailed since implementing preventive measures is unclear. ⋯ Co-infection with SARS-CoV-2 and other viruses was not observed. Causative viruses remain prevalent after implementing preventive measures. SARS-CoV-2 differs from influenza viruses in its infectivity.
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Since the emergence of SARS-CoV-2 numerous antibody assays have become available, demonstrating different performance characteristics. This study focused on a quantitative correlation between different commercial assays and a neutralization test (NT). Comparative data is needed as a basis for the production of convalescent plasma and potential interpretations COVID-19 immunity. ⋯ An infection without fever and negative or weakly positive reactions in the Wantai Rapid test were negative predictive factors for NT titers >1:200 (negative predictive value of 92 % and 92 % respectively, combination of both 100 %). The Wantai ELISA titer could be a suitable substitute for NT. An adequate pooling strategy of plasma units additionally could compensate deviations of individual antibody titers.
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Comparative Study
Performance of six SARS-CoV-2 immunoassays in comparison with microneutralisation.
There is an urgent need for reliable high-throughput serological assays for the management of the ongoing COVID-19 pandemic. Preferably, the performance of serological tests for a novel virus should be determined with clinical specimens against a gold standard, i.e. virus neutralisation. We compared the performance of six commercial immunoassays for the detection of SARS-COV-2 IgG, IgA and IgM antibodies, including four automated assays [Abbott SARS-COV-2 IgG (CE marked), Diasorin Liaison® SARS-COV-2 S1/S2 IgG (research use only, RUO), and Euroimmun SARS-COV-2 IgG and IgA (CE marked)], and two rapid lateral flow (immunocromatographic) tests [Acro Biotech 2019-nCoV IgG/IgM (CE marked) and Xiamen Biotime Biotechnology SARS-COV-2 IgG/IgM (CE marked)] with a microneutralisation test (MNT). ⋯ The specificity and sensitivity values of the commercial tests against MNT, respectively, were as follows: 95.1 %/80.5 % (Abbott Architect SARS-CoV-2 IgG), 94.9 %/43.8 % (Diasorin Liaison SARS-CoV-2 IgG; RUO), 68.3 %/87.8 % (Euroimmun SARS-CoV-2 IgA), 86.6 %/70.7 % (Euroimmun SARS-CoV-2 IgG), 74.4 %/56.1 % (Acro 2019-nCoV IgG), 69.5 %/46.3 % (Acro 2019-nCoV IgM), 97.5 %/71.9 % (Xiamen Biotime SARS-CoV-2 IgG), and 88.8 %/81.3 % (Xiamen Biotime SARS-CoV-2 IgM). This study shows variable performance values. Laboratories should carefully consider their testing process, such as a two-tier approach, in order to optimize the overall performance of SARS- CoV-2 serodiagnostics.
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The emergence of new SARS-CoV-2 has promoted the development of new serological tests that could be complementary to RT-PCR. Nevertheless, the assessment of clinical performances of available tests is urgently required as their use has just been initiated for diagnose. ⋯ Excellent sensitivity for IgG detection was obtained >14 days after onset of symptoms for all immunoassays. Specificity was also excellent for IgG CLIA and IgG LFIA. Our study shows that NG-Test® is reliable and accurate for routine use in clinical laboratories.
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As the Coronavirus 2019 (COVID-19) pandemic evolves, the development of immunoassays to help determine exposure and potentially predict immunity has become a pressing priority. In this report we present the performance of the EUROIMMUN enzyme-linked immunosorbent assay (ELISA) for semi-quantitative detection of IgA and IgG antibodies in serum and plasma samples using recombinant S1 domain of the SARS-CoV-2 spike protein as antigen. Specimens from patients, with and without COVID-19 infection, were tested at the University of Chicago Clinical Microbiology and Immunology Laboratory. ⋯ Of samples collected ≥4 days after positive PCR, 38 of 42 (90.5% agreement, 95% CI: 77.9-96.2) were positive for IgA, and 42 of 42 (100% agreement, 95% CI: 91.6-100) were positive for IgG, respectively. The EUROIMMUN Anti-SARS-CoV-2 ELISA Assay demonstrated good sensitivity for detection of IgA and excellent sensitivity for detection of IgG antibodies from samples collected ≥4 days, after COVID-19 diagnosis by PCR. This assay demonstrated good specificity for IgA and excellent specificity for IgG and demonstrated only borderline cross reaction in 2 of the 28 samples from patients with common human coronaviruses infection, types NL63 and OC43.