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 messenger RNA (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.
OUTCOME: 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.
PLAIN-LANGUAGE SUMMARY: People with kidney failure treated with maintenance dialysis are at increased risk of severe COVID-19. The role of COVID-19 vaccination in this population is not well characterized. Between September 4, 2022, and April 1, 2023, the relative effectiveness of a bivalent mRNA COVID-19 vaccine dose compared with receipt of original monovalent COVID-19 vaccine doses alone among adults aged ≥18 years with kidney failure treated with maintenance dialysis but without additional immunocompromising conditions was 41% (95% CI, 37%-46%) against medically attended COVID-19, with the estimated effectiveness being similar for severe outcomes like COVID-19-associated hospitalization and COVID-19-associated death. COVD-19 vaccine effectiveness among these adults waned with more time since vaccination.
