- women who are pregnant or breastfeeding To reflect the real-world population of hemodialysis patients, the NEPHRO-VAChemodialysis project is designed as inclusive as possible. Exclusion criteria are minimal and serve to exclude patients who are not evaluable, or in whom vaccination is considered not safe or not effective. Since baseline blood samples before vaccination will provide an individual reference level of antibody measures, potential bias can be anticipated for. As such, we can still evaluate the immune response induced by the vaccination only. Moreover, At baseline (ie before vaccination) blood samples will be taken. The existence of SARS-Cov-2 antibodies will be examined in the samples in retrospect. As such, based on the baseline antibody levels, we can divide the study population in a COVID+ and COVID- subgroup and perform subgroup analysis to evaluate the effect of this variable. We feel it is not feasible and necessary to exclude patients for the trial based on prevaccination SARS-CoV-2 antibody positivity. First of all the procedures in the study reflect the real life situation. Secondly, analyzing the study results the revaccination antibody levels will be a variable used in the analysis.

- women who are pregnant or breastfeeding To reflect the real-world population of hemodialysis patients, the NEPHRO-VAChemodialysis project is designed as inclusive as possible. Exclusion criteria are minimal and serve to exclude patients who are not evaluable, or in whom vaccination is considered not safe or not effective. Since baseline blood samples before vaccination will provide an individual reference level of antibody measures, potential bias can be anticipated for. As such, we can still evaluate the immune response induced by the vaccination only. Moreover, At baseline (ie before vaccination) blood samples will be taken. The existence of SARS-Cov-2 antibodies will be examined in the samples in retrospect. As such, based on the baseline antibody levels, we can divide the study population in a COVID+ and COVID- subgroup and perform subgroup analysis to evaluate the effect of this variable. We feel it is not feasible and necessary to exclude patients for the trial based on prevaccination SARS-CoV-2 antibody positivity. First of all the procedures in the study reflect the real life situation. Secondly, analyzing the study results the revaccination antibody levels will be a variable used in the analysis.