Identification of Clinical Factors Associated With the Immunogenicity of Homologous <scp>ChAdOx1</scp> ‐ <scp>nCoV</scp> ‐19 Vaccine in Hemodialysis Patients

Hemodialysis (HD) patients are at higher risk of severe COVID-19 and may exhibit suboptimal vaccine responses. This study evaluates the factors influencing vaccine-induced immunity in HD patients following the second dose of the Vaxzevria. A total of 276 HD patients and 126 controls were included. Antibody responses were assessed using binding antibody units (BAU). Operational antibody thresholds used in prior literature were applied to classify antibody levels as evaluated as 50% and 60% vaccine efficacy (VE) levels after the first dose and second dose separately. Linear regression model and stratification by baseline characteristics were performed to identify clinical factors associated with vaccine responses. HD patients had significantly lower median antibody levels compared to healthy subjects. Antibody levels decreased with age, with the oldest tertile having the lowest response. Higher BMI and favorable body composition, such as increased fat tissue index, were positively correlated with stronger immune responses. Patients with elderly, diabetes mellitus, heart failure, and low BMI were associated with reduced antibody responses and lower rates of achieving 50% and 60% VE thresholds. Vaccine-induced immunity in HD patients is influenced by age, BMI, body composition, and comorbidities. Tailored vaccination strategies, including booster doses, are essential to enhance protection in this vulnerable population.