Effectiveness of Bivalent mRNA COVID-19 Vaccine Among Adults With Kidney Failure Receiving Dialysis: A Cohort Study From the Centers for Medicare and Medicaid Services.

Abstract

RATIONAL & OBJECTIVE Patients with kidney failure treated with maintenance dialysis have an increased risk of severe disease due to SARS-CoV-2 infection, the virus that causes COVID-19. Previous studies have shown that COVID-19 vaccination is effective against severe COVID-19 illness in the general population. However, less is known about populations at greater risk for severe disease. This investigation examined the real-world effectiveness of bivalent mRNA COVID-19 vaccination against clinical outcomes among patients treated with maintenance dialysis. STUDY DESIGN Retrospective cohort study. SETTING & PARTICIPANTS Medicare Fee-for-Service (FFS) claims data for beneficiaries aged ≥18 years with kidney failure receiving maintenance dialysis between September 4, 2022, and April 1, 2023. EXPOSURE Bivalent mRNA COVID-19 vaccination compared with receipt of original monovalent COVID-19 doses alone. OUTCOMES Medically attended COVID-19, which was defined as the occurrence of a COVID-19-associated outpatient encounter, COVID-19-associated hospitalization, critical COVID-19 illness, or COVID-19-associated death, overall as well as each COVID-19-associated outcome individually. ANALYTICAL APPROACH Relative vaccine effectiveness against COVID-19-associated outcomes was calculated as 1 - adjusted hazard ratio, with the adjusted hazard ratio comparing rates of outcomes by vaccination status estimated using a weighted Cox regression model. RESULTS Compared with receipt of original monovalent COVID-19 vaccine doses, the relative estimated effectiveness of a bivalent mRNA COVID-19 vaccine dose was 41% (95% CI: 37%, 46%) against medically attended COVID-19, 49% (95% CI: 43%, 54%) against COVID-19-associated hospitalization, 53% (95% CI: 44%, 61%) against critical COVID-19 illness, and 54% (95% CI: 42%, 63%) against COVID-19-associated death among adults with kidney failure treated with maintenance dialysis without additional immunocompromising conditions. Estimated vaccine effectiveness against medically attended COVID-19 was 50% (95% CI: 44%, 55%) 7-59 days after bivalent vaccination and 33% (95% CI: 26%, 39%) 60-206 days after bivalent vaccination. LIMITATIONS Potential misclassification bias, residual confounding, and generalizability concerns may exist. CONCLUSIONS These findings suggest a bivalent mRNA COVID-19 vaccine dose provided protection against COVID-19 disease among previously vaccinated persons with kidney failure receiving maintenance dialysis, but the estimated effectiveness waned over time.