ABSTRACT
Background: Obesity is established as a key correlate of severe SARS-CoV-2 outcomes. Multiple other epidemiological and immunological features are less well-defined including whether obesity increases susceptibility to SARS-CoV-2, influences symptom phenotype, or impedes or alters the immune response to infection. Given the substantial global burden of obesity and given these uncertainties, we examined the epidemiology and immunology of obesity and SARS-CoV-2. Methods: Industry employees were invited to participate in a prospective SARS-CoV-2 serology-based cohort study. Blood and baseline survey measures that included demographics, comorbidities, and prior COVID-19 compatible symptoms were collected. Serological testing and interim symptom reporting were conducted monthly. SARS-CoV-2 immunoassays included an IgG ELISA targeting the spike RBD, multiarray Luminex targeting 20 viral antigens, pseudovirus neutralization, and T cell ELISPOT assays. Unadjusted and adjusted analyses were used to identify differences in seroprevalence, clinical features, and immune parameters by BMI. Results: Of 4469 individuals enrolled, 322 (7.21%) were seropositive. Adjusted seroprevalence was non-significantly lower with higher BMI. Obesity was associated with increased reporting of fever (OR 3.43 [95% CI 1.58-7.60]) and multiple other symptoms and aggregate measures. There were no identifiable differences in immune response between obese and non-obese individuals. Discussion: We present benchmark data that obesity is not linked to increased risk of SARS-CoV-2 infection; that symptom phenotype is strongly influenced by obesity; and that despite evidence of obesity-associated immune dysregulation in severe infections, there is no evidence of muted or dysfunctional immune response across multiple immune measures among non-severe infections.
Subject(s)
COVID-19 , Obesity , Fever , Sexual Dysfunction, PhysiologicalABSTRACT
Background Seroepidemiology is an important tool to characterize the epidemiology and immunobiology of SARS-CoV-2 but many immunoassays have not been externally validated raising questions about reliability of study findings. To ensure meaningful data, particularly in a low seroprevalence population, assays need to be rigorously characterized with high specificity. Methods We evaluated two commercial (Roche Diagnostics and Epitope Diagnostics IgM/IgG) and two non-commercial (Simoa and Ragon/MGH IgG) immunoassays against 68 confirmed positive and 232 pre-pandemic negative controls. Sensitivity was stratified by time from symptom onset. The Simoa multiplex assay applied three pre-defined algorithm models to determine sample result. Results The Roche and Ragon/MGH IgG assays each registered 1/232 false positive, the primary Simoa model registered 2/232 false positives, and the Epitope registered 2/230 and 3/230 false positives for the IgG and IgM assays respectively. Sensitivity >21 days post symptom-onset was 100% for all assays except Epitope IgM, but lower and/or with greater variability between assays for samples collected 9-14 days (67-100%) and 15-21 days (69-100%) post-symptom onset. The Simoa and Epitope IgG assays demonstrated excellent sensitivity earlier in the disease course. The Roche and Ragon/MGH IgG assays were less sensitive during early disease, particularly among immunosuppressed individuals. Conclusions The Epitope IgG demonstrated good sensitivity and specificity. The Roche and Ragon/MGH IgG assays registered rare false positives with lower early sensitivity. The Simoa assay primary model had excellent sensitivity and few false positives.