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- Title
Are anti-SARS-CoV-2 S/N IgG/IgM antibodies always predictive of previous SARS-CoV-2 infection?
- Authors
Lippi, Giuseppe; Henry, Brandon M.; Pighi, Laura; De Nitto, Simone; Salvagno, Gian Luca
- Abstract
We planned this study to verify whether immunoassays for quantifying anti-SARS-CoV-2 IgG/IgM antibodies against both spike (S) and nucleocapsid (N) proteins may be used for identifying previous SARS-CoV-2 infections. The study population consisted of a cohort of fully vaccinated healthcare workers. All study subjects underwent regular medical visits and molecular testing for diagnosing SARS-CoV-2 infections every 2–4 weeks between 2020–2022. Venous blood was drawn for measuring anti-SARS-CoV-2 antibodies with MAGLUMI 2019-nCoV lgG/IgM CLIA Assays directed against both SARS-CoV-2 S and N proteins. Overall, 31/53 (58.5%) subjects had tested positive for SARS-CoV-2 by RT-PCR throughout the study (24 once, 7 twice). No positive correlation was found between anti-SARS-CoV-2 S/N IgM antibodies and molecular test positivity. In univariate regression analysis, both a molecular test positivity (r=0.33; p=0.015) and the number of positive molecular tests (r=0.43; p=0.001), but not vaccine doses (r=−0.12; p=0.392), were significantly correlated with anti-SARS-CoV-2 S/N IgG antibodies. These two associations remained significant in multiple linear regression analysis (p=0.029 and p<0.001, respectively) after adjusting for sex, age, body mass index, and vaccine doses. In ROC curve analysis, anti-SARS-CoV-2 S/N IgG antibodies significantly predicted molecular test positivity (AUC, 0.69; 95% CI; 0.55–0.84), with the best cutoff of 0.05 AU/mL displaying 67.9% accuracy, 0.97 sensitivity, and 0.27 specificity. Although anti-SARS-CoV-2 S/N IgG antibodies provide helpful information for identifying previous SARS-CoV-2 infections, a lower cutoff than that of sample reactivity should be used. Anti-SARS-CoV-2 S/N IgM antibodies using conventional cutoffs seem useless for this purpose.
- Subjects
RESEARCH; STATISTICS; COVID-19; SARS-CoV-2; IMMUNOGLOBULINS; VIRAL proteins; CONFIDENCE intervals; CORONAVIRUS spike protein; COVID-19 vaccines; MULTIPLE regression analysis; IMMUNOASSAY; MOLECULAR biology; DESCRIPTIVE statistics; VIRAL antibodies; STATISTICAL correlation; RECEIVER operating characteristic curves; SENSITIVITY &; specificity (Statistics); LONGITUDINAL method
- Publication
Advances in Laboratory Medicine / Avances en Medicina de Laboratorio, 2023, Vol 4, Issue 2, p175
- ISSN
2628-491X
- Publication type
Article
- DOI
10.1515/almed-2023-0008