Hepcidin and other obesity-related factors affecting BNT162b2 response in children and adolescents over a 6-month period.

Abstract

Background Obesity causes chronic inflammation and metabolic dysregulation of the immune response and increases an individual's susceptibility to severe infection. Purpose This study aimed to evaluate the effect of an increased body mass index (BMI), obesity-associated biomarkers, and habitual factors on immune responses following BNT162b2 vaccination in a pediatric population over a 6-month period. Methods In this prospective, single-center cohort study, the participants received a 2-dose regimen of the BNT16 2b2 mRNA vaccine. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) and neutralizing antibody (Ab) levels were measured before vaccination (T0), 14 days after vaccination (T1), and 6 months after the second dose (T2). Baseline anthropometric and biochemical assessments including BMI measurements were performed at T0. Lifestyle characteristics were evaluated using a standardized questionnaire administered at baseline. Results T2 SARS-CoV-2 neutralizing Ab levels were significantly lower in overweight or obese participants (P= 0.02). Among the other biochemical markers, hepcidin, and leptin levels were significantly correlated with BMI (P= 0.004 and P<0.001, respectively). The main biochemical parameters that were inversely correlated with T1 IgG and neutralizing titers were uric acid (P=0.007, P<0.001), fasting serum glucose-to-plasma insulin ratio (P=0.02 and P=0.02), and hepcidin (P=0.01 and P=0.01). Passive smoking was associated with lower T2 IgG titers (P=0.04). Higher uric acid levels and a lower KIDMED index were associated with reduced T2 SARS-CoV-2 neutralizingtiters (P=0.005 and P=0.02, respectively). Reactogenicity was significantly correlated with BMI and age (P=0.03 and P= 0.02, respectively), whereas higher hepcidin and uric acid levels were associated with the presence of local and systemic adverse effects, respectively (P=0.008 and P= 0.02, respectively). Conclusion Our findings suggest that obesity-related environmental and behavioral factors may be associated with humoral immune responses during 6 months of follow-up.