Effectiveness of COVID-19 vaccination among dialysis and kidney transplant patients compared with matched controls-a nationwide cohort study.

Objectives: Patients undergoing long-term kidney replacement therapy (KRT) have an increased risk of morbidity and mortality due to COVID-19. This study aimed to evaluate the real-world effectiveness of COVID-19 vaccination in reducing hospitalization and mortality due to COVID-19 among dialysis and kidney transplant patients.

Methods: We obtained data on all patients receiving KRT from the Finnish Registry for Kidney Diseases. For each patient, 10 controls from the Finnish population registry were matched by age, sex, and municipality. Hazard ratios of hospitalizations and deaths due to COVID-19 were calculated by vaccination status among dialysis patients, kidney transplant recipients, and controls to estimate vaccine effectiveness.

Results: In total, 5755 KRT patients, including 2547 on dialysis and 3208 kidney transplant recipients, were compared with 57 253 controls. Overall, 784 (30.8%) dialysis patients, 929 (29.0%) kidney transplant recipients, and 10 702 (18.7%) controls were infected with SARS-CoV-2 between 1 January 2020 and 31 December 2022. With 2-3 vaccine doses, vaccine effectiveness against hospitalization due to COVID-19 was 47% (95% CI: 12-68%) in dialysis patients, 50% (95% CI: 26-66%) in kidney transplant recipients, and 76% (95% CI: 69-82%) in controls. In kidney transplant recipients, receiving more than three vaccine doses reduced COVID-19-related mortality by 62% (95% CI: 14-83%), whereas the reduction in mortality in dialysis patients was not statistically significant.

Discussion: Vaccination was associated with significantly reduced hospitalization due to COVID-19 among KRT patients, and more than three vaccine doses were associated with reduced mortality in kidney transplant recipients, highlighting the importance of booster vaccinations in this vulnerable group.