#3163 sars-cov-2 omicron infections among vaccinated maintenance hemodialysis patients: outcomes and comparison to delta variant

Abstract Background and Aims Infections with the B.1.1.529 Omicron variant of SARS-CoV-2 became predominant worldwide in late 2021, replacing the previously dominant B.1.617.2 Delta variant. While these variants are highly transmissible and can evade vaccine protection, population studies suggested that outcomes after infection with Omicron variant were better than with Delta. Data regarding prognosis of maintenance hemodialysis (MHD) patients infected with Omicron vs. Delta variants are limited. Method This retrospective, cohort study included all patients with end-stage kidney disease treated with MHD at Meir Medical Center, Kfar Saba, Israel, who were diagnosed with SARS-CoV-2 infection between June 2021 and May 2022. Results Twenty-six MHD patients were diagnosed with the Delta variant and 71 with Omicron. SARS-CoV-2 infection severity was significantly worse among those infected with the Delta variant: 50% developed severe or critical COVID-19 vs. 5% in the Omicron group (p<0.001). Among MHD infected with Omicron, 57% were asymptomatic during their illness. For the entire cohort, 30-day mortality was 5.2%. It was higher among MHD in the Delta group (5/26, 19.2%) than in the Omicron group (0/71; p<0.001), as was 90-day mortality (5/26, 19.2% vs. 3/71, 4.2%, respectively; p = 0.02). Mean age was comparable between groups. Patients infected with Omicron variant received a higher mean number of vaccine doses before infection, as compared to Delta group (p<0.001). Conclusion Infection with the SARS-CoV-2 Delta variant was associated with worse outcomes compared with Omicron, among patients on MHD. However, despite mild disease among vaccinated MHD patients, infection with Omicron variant was still associated with significant 90-day mortality rate.