ABSTRACT
Introduction: Obesity is considered one of the possible risk factors for hospitalization and intensive care in Covid-19 patients. It is believed that obesity may compromise some steps of the immune response and may affect the development of post-vaccine immunological memory. The aim of our study was to assess the post-vaccination IgG response against the spike protein (S-RBD IgG) in relation to age, gender and body mass index (BMI). Material and Methods: The study involved 766 Healthcare Workers who received two doses of BioNTech/Pfizer vaccination (December 2020-March 2021) and were tested for S-RBD IgG (CMIA) 20-40 days after the second vaccine dose. These subjects were always negative to SARS CoV-2 nasopharyngeal periodical swabs and were negative to Ab anti SARS-CoV-2 S1/S2 IgG (CLIA) measured before the first dose of vaccine. Results: The 766 workers (70.8% female and 29.2% male) were all positive for the antibody levels determined after the second dose of vaccine (S-RDB IgG range: 190.8-63093 AU/mL). Multivariable data analysis showed that the increase in the S-RBD IgG was more pronounced in younger subjects (p<0.001) and in women (p<0.05). Data analysis also showed an increase in the levels of S-RDB IgG in subjects with greater BMI (p<0.05). Conclusion: At a first check (20-40 days after the vaccination), the SARS-Co-V-2 antibody levels in the studied sample were influenced by age and gender, as expected. Contrary to data reported by others, subjects with greater BMI showed an increased antibody response, but this finding, as well as the temporal trend of antibody levels, need to be further investigated.
ABSTRACT
Background: The approach to diagnosing, treating and monitoring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection relies strongly on laboratory resources, with serological testing representing the mainstay for studying the onset, nature and persistence of humoral immune response. This study was aimed at evaluating the analytical performance of the novel Beckman Coulter anti-SARS-CoV-2 immunoglobulins G (IgG) chemiluminescent immunoassay. Methods: This analytical assessment encompassed the calculation of intra-assay, inter-assay and total imprecision, linearity, limit of blank (LOB), limit of detection (LOD), functional sensitivity, and comparison of anti-SARS-CoV-2 antibodies values obtained on paired serum samples using DiaSorin Liaison SARS-CoV-2 S1/S2 IgG and Roche Elecsys Anti-SARS-CoV-2 total antibodies. Diagnostic performance was also tested against results of molecular testing on nasopharyngeal swabs, collected over the previous 4 months. Results: Intra-assay, inter-assay and total imprecision of Beckman Coulter anti-SARS-CoV-2 IgG were between 4.3-4.8%, 2.3-3.9% and 4.9-6.2%, respectively. The linearity of the assay was excellent between 0.11-18.8 antibody titers. The LOB, LOD and functional sensitivity were 0.02, 0.02 and 0.05, respectively. The diagnostic accuracy (area under the curve;AUC) of Beckman Coulter anti-SARS-CoV-2 IgG compared to molecular testing was 0.87 (95% CI, 0.84-0.91;P<0.001) using manufacturer's cut-off, and increased to 0.90 (95% CI, 0.86-0.94;P<0.001) with antibody titers. The AUC was non-significantly different from that of Roche Elecsys Anti-SARS-CoV-2, but was always higher than that of DiaSorin Liaison SARS-CoV-2 S1/S2 IgG. The correlation of Beckman Coulter Access SARS-CoV-2 IgG was 0.80 (95% CI, 0.75-0.84;P<0.001) with Roche Elecsys Anti-SARS-CoV-2 and 0.72 (95% CI, 0.66-0.77;P<0.001) with DiaSorin Liaison SARS-CoV-2 S1/S2 IgG, respectively. Conclusions: The results of this analytical evaluation of Beckman Coulter Access anti-SARS-CoV-2 IgG suggests that this fully-automated chemiluminescent immunoassay represents a valuable resource for large and accurate seroprevalence surveys. © Journal of Laboratory and Precision Medicine. All rights reserved.