Severe Acute Respiratory Coronavirus-2 Antibody and T cell response after a third vaccine dose in hemodialysis patients compared with healthy controls

1. Hemodialysis patients (HD patients) have a high health risk from Severe Acute Respiratory Coronavirus-2 (SARS-CoV-2) infection. In this study, we assess the impact of a third vaccine dose (3D) on antibody levels and T cell response in HD patients and compare the results to those of a healthy control group. We conducted a prospective cohort study consisting of 60 HD patients and 65 healthy controls. All of them received two doses of the Comirnaty mRNA vaccine and a third mRNA vaccine dose (Spikevax or Comirnaty). The SARS-CoV-2 S antibody response in all participants was measured 6 months after the second vaccine dose and 6 to 8 weeks after administration of the 3D. We also assessed INF-γ secretion 6–8 weeks after the 3D in 24 healthy controls, 17 HD patients with a normal and 20 HD patients with a low or no antibody response after the second dose. The groups were compared using univariate quantile regressions and multiple analyses. The adverse effects of vaccines were assessed via a questionnaire. After the 3D, the SARS-CoV-2-specific antibody and INF-γ titers of most HD patients were comparable to those of healthy controls. A subgroup of HD patients who had shown a diminished antibody response after the first two vaccine doses developed a significantly lower antibody and INF-γ response compared to responder HD patients and controls, even after the 3D. A new strategy is needed to protect this patient group from severe COVID-19 infection.