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BACKGROUND: Monitoring antibody response following SARS-CoV-2 vaccination is strategic, and neutralizing antibodies represent the gold standard. The neutralizing response to Beta and Omicron VOCs was evaluated versus the gold standard by a new commercial automated assay. METHODS: Serum samples from 100 healthcare workers from the Fondazione Policlinico Universitario Campus Biomedico and the Pescara Hospital were collected. IgG levels were determined by chemiluminescent immunoassay (Abbott Laboratories, Wiesbaden, Germany) and serum neutralization assay as the gold standard. Moreover, a new commercial immunoassay, the PETIA test Nab (SGM, Rome, Italy), was used for neutralization evaluation. Statistical analysis was performed with R software, version 3.6.0. RESULTS: Anti-SARS-CoV-2 IgG titers decayed during the first ninety days after the vaccine second dose. The following booster dose significantly (p < 0.001) increased IgG levels. A correlation between IgG expression and neutralizing activity modulation was found with a significant increase after the second and the third booster dose (p < 0.05. Compared to the Beta variant of the virus, the Omicron VOC was associated with a significantly larger quantity of IgG antibodies needed to achieve the same degree of neutralization. The best Nab test cutoff for high neutralization titer (≥1:80) was set for both Beta and Omicron variants. CONCLUSION: This study correlates vaccine-induced IgG expression and neutralizing activity using a new PETIA assay, suggesting its usefulness for SARS-CoV2 infection management.
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INTRODUCTION: Diabetes mellitus worsens the prognosis of SARS-CoV-2 infection, and vaccination has been the major tool for reducing the risk of hospitalisation, and mortality. The primary aim of this study was to evaluate the response to the SARS-CoV-2 vaccine in subjects with diabetes and controls. Differences between type 1 (T1D) and type 2 (T2D) diabetes and clinical determinants of vaccination response were also evaluated. METHODS: 128 subjects with diabetes (60 with T1D and 62 with T2D) and 202 subjects acting as controls who completed a full vaccination cycle with two doses of mRNA vaccine were enroled. People with previous SARS-CoV-2 infection were excluded. Antibodies (Ab) directed against the spike protein of the SARS-CoV-2 were evaluated at one and 6 months after vaccination. RESULTS: In the whole cohort, the Ab level was higher among women than in men (p = 0.011) and negatively correlated with age (rho = -0.155, p = 0.005). Subjects with diabetes showed decreased levels of Ab after one month compared to controls (1217[747-1887]BAU/mL vs. 1477[942-2556]BAU/mL, p = 0.002), even after correction for age and gender (p = 0.002). No difference was found between subjects with T1D and T2D. After 6 months, antibody levels significantly decreased in people with and without diabetes, with no differences between groups, although some subjects were lost at follow-up. In subjects with diabetes, only a significant correlation was found between Ab level and renal function (rho 0.190, p = 0.042). CONCLUSIONS: Both T1D and T2D are associated with a reduced early response to vaccination. The serum concentration of Ab significantly reduced over time in both groups, highlighting the relevance of vaccination boosters independently of the presence of diabetes.
