Abstract
Background: Vaccination against SARS-CoV-2 has been pivotal in controlling the COVID-19 pandemic. However, understanding vaccine-induced immunity in immunocompromised individuals remains critical, particularly how prior exposure to other coronaviruses modulates immune responses. The influence of previous infections with endemic human coronaviruses (HCoVs), such as OC43, on SARS-CoV-2 immunity is not fully understood. This study evaluates antibody responses to COVID-19 vaccination in hemodialysis patients (HD), transplant recipients (TR), and healthy controls (CO), accounting for prior SARS-CoV-2 infection and baseline human coronavirus (HCoV) reactivity. Methods: We obtained longitudinal antibody measurements from 70 subjects (CO: n = 33; HD: n = 13; TR: n = 24) and assessed antibody kinetics across multiple post-vaccination time points using multivariate linear mixed modeling (MLMM). Results: Limited but measurable cross-reactivity was observed between SARS-CoV-2 and endemic HCoVs, particularly the β-coronavirus OC43. Pre-existing immunity in healthy individuals modestly enhanced vaccine-induced anti-spike (S) IgG responses, supported by post-vaccination increases in SARS-CoV-2 IgG. Prior SARS-CoV-2 infection significantly influenced anti-S and nucleocapsid (N) IgG responses but had limited impact on endemic HCoVs responses. Vaccine type and immune status significantly affected antibody kinetics. mRNA vaccination (BNT162b2) elicited stronger and more durable SARS-CoV-2 anti-S IgG responses than the inactivated CoronaVac vaccine, especially in immunocompetent individuals. Immunocompromised groups showed delayed or attenuated responses, with modest anti-S IgG cross-reactive boosting. Elevated anti-N IgG in CoronaVac recipients raised questions about its origin-infection or vaccine effects. MLMM identified key immunological and clinical predictors of antibody responses, emphasizing the critical role of host immune history. Conclusions: These findings highlight a constrained but meaningful role for HCoV cross-reactivity in SARS-CoV-2 immunity and vaccine responsiveness, underscore the need for infection markers unaffected by vaccination, and support development of broadly protective pan-coronavirus vaccines and tailored strategies for at-risk populations.