Background: Coronavirus disease 2019 (COVID-19) is a rapidly changing disease. So, in this study, we evaluated the evolution of COVID-19 presentation and course in hemodialysis patients (HD). Methods: We retrospectively compared clinical data and outcomes of HD patients affected by COVID-19 during the first pandemic waves of 2020 (from March to December 2020- Group 1) with patients diagnosed with COVID-19 from September 2021 to February 2022 (Group 2), after the full completion of vaccination. Then, we distinguished among them patients responsive (antibody levels > 13 BAU/ml) and unresponsive to the vaccine. We collected data on COVID-19 clinical presentation, laboratory examinations, and outcomes. Results: Group 1 was constituted of 44 patients (69.3±14.6 years) and Group 2 of 55 patients (67.4±15.3 years). Among Group 2, fifty-two patients (95%) were vaccinated, 43 of them (83%) with three doses. Patients of Group 2, compared with Group 1, were more often asymptomatic (38 vs 10%, p=0.002), and reported less frequent fever and pulmonary involvement. At diagnosis, the Group 2 showed a significantly higher number of lymphocytes (0.97±0.45 vs 0.69±0.35 cells x10 9 /L, p=0.008) and lower levels of circulating IL-6 (16±13.3 vs 41±39.4 pg/ml, p=0.002). Moreover, in Group 2, inflammatory parameters significantly improved after a few days from diagnosis. Patients of Group 2 presented a lower hospitalization rate (12.7 vs 38%, p=0.004), illness duration (18.8±7.7 vs 29.2±19.5 days, p=0.005), and mortality rate (5.4 vs 25%, p= 0.008). Finally, responders to the vaccination (80% of the vaccinated patients) compared with non-responders showed a reduction in infection duration and hospitalization (5 vs 40%, p=0.018). Conclusions: COVID-19 presentation and course in HD patients have improved over time after the implementation of vaccine campaigns. However, due to the evolving nature of the disease, active surveillance is necessary.

The authors have declared no competing interest.

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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The study was performed according to the Declaration of Helsinki and was approved by the local Ethics Committee (N. Registro CER Liguria: 135/2020). All participants provided written informed consent before enrollment.

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