SARS-CoV-2 vaccine efficacy and severe outcomes in patients on maintenance dialysis
Vaccination trials in the hemodialysis population showed a weaker antibody response than healthy controls, but the utility of the vaccine in preventing SARS-CoV-2 infection and serious illness was unknown. Between December 21, 2020 and June 30, 2021, researchers conducted a retrospective cohort study in the Canadian province of Ontario. Using provincial health administrative data, they were able to assess vaccination receipt, SARS-CoV-2 infection, and serious outcomes (hospitalization or death). Receipt of one or two doses of vaccine was modeled in a cause-specific, time-varying Cox proportional hazards model with baseline characteristics, baseline infection rates in the community, and censorship for non-COVID deaths, recovered kidney function, out-of-province transfer, solid organ transplant, and dialysis withdrawal are all considered.
As of June 30, 2021, 2,403 (17%) of 13,759 people on maintenance dialysis were unvaccinated, while 11,356 (83%) had received at least one dose. BNT162b2 (n=8455, 74%) and mRNA-1273 (n=2901, 26%) vaccines were used; the median interval between the first and second dose was 36 days (IQR 28–51). For a comparison with an unvaccinated vaccine, the adjusted relative risk (HR) for SARS-CoV-2 infection and serious outcomes was 0.59 (95% CI, 0.46 to 0.76) and 0.54 (95% CI, 0.37 to 0.77), respectively, and for two doses compared to unvaccinated, the adjusted hazard ratio (HR) was 0.31 (95% CI , 0.22 to 0.42) and 0.17 (95% CI, 0.1 to 0.1). Vaccination efficacy did not differ significantly by age, dialysis method, or vaccine type. Despite concerns about weak antibody responses, vaccination against COVID-19 prevented SARS-CoV-2 infection and catastrophic outcomes in dialysis patients.