Diagnostic accuracy of three SARS-CoV2 antibody detection assays, neutralizing effect and longevity of serum antibodies

• Published in: Journal of virological methods Vol. 293; p. 114173
• Main Authors: Bubonja-Šonje, Marina, Batičić, Lara, Abram, Maja, Cekinović Grbeša, Đurđica
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-07-2021
• Subjects: Antibodies, Neutralizing - blood; Antibodies, Viral - blood; Antibody testing; COVID-19; COVID-19 - diagnosis; COVID-19 Serological Testing - methods; Humans; Immunoglobulin G - blood; Immunoglobulin M - blood; Neutralization Tests; SARS-CoV-2 - immunology; SARS-CoV-2 neutralizing activity; Sensitivity and Specificity; Serological testing; COVID-19; Antibody testing; Serological testing; SARS-CoV-2 neutralizing activity
• ISSN: 0166-0934; 1879-0984; 1879-0984
• DOI: 10.1016/j.jviromet.2021.114173

•Assessed SARS-CoV-2 immunoassays have diagnostic accuracy from 99 % to 100 %.•Sensitivity of IgG assays is greater than 95 %, specificity greater than 99 %.•Longevity of SARS-CoV-2 IgG in symptomatic COVID patients is at least eight months.•Severe disease is associated with higher IgG titers and neutralizing activity.•IgG assays showed strong positive correlation to neutralizing activity.
Evidence is currently insufficient to know whether SARS-CoV-2 antibodies (Abs) protect from future infection and how long immunity will last. The kinetics of the immune response to SARS-CoV-2 infection and role of serology in estimating individual protective immunity is yet to be established. We evaluated diagnostic performances of three serological assays - Abbott Architect CMIA IgG, bioMerieux VIDAS ELFA IgG/IgM, and Diesse Chorus ELISA IgG/IgM, and analyzed longevity and potential neutralizing effect of SARS-CoV-2 Abs in COVID-19 patients. Clinical sensitivities of assessed IgG tests two to three weeks post symptom onset (PSO) were very high: 96.77 % for Architect, 96.77 % for Chorus, and 100.00 % for VIDAS. Sensitivities of two assessed IgM assays were moderate: 74.07 % for Chorus, and 76.92 % for VIDAS. Specificities were excellent for all assessed IgG assays: 99.01 % for Architect and 100 % for Chorus and VIDAS. Chorus and VIDAS IgM assays also achieved excellent specificity of 99.01 % and 100 %, respectively. In most cases IgG Abs were still present eight months PSO. Neutralizing antibodies were detected in majority of serum samples from convalescent patients. Serum samples from severe COVID-19 patients had higher antibody titers and higher neutralizing activity. We observed a strong positive correlation among SARS-CoV-2 IgG antibody titer and neutralizing activity. The strongest positive correlation to neutralizing activity was found for VIDAS IgG assay.