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Background: Vulnerable populations, such as hemodialysis (HD) patients and kidney transplant (RTx) recipients, have priority for anti-COVID-19 vaccination, because of their impaired immune status. Here, we investigated the immune response after vaccination with BNT162b2 (two doses plus booster) in HD and RTx patients., Methods: A prospective, observational study was started in two homogeneous groups of 55 HD and 51 RTx patients previously matched from a cohort of 336 patients. Anti-RBD IgG levels, assayed after the second dose with BNT162b2 mRNA, were used to stratify subjects into quintiles. After the second dose and after booster, anti-RBD and IGRA test were evaluated in RTx and HD, belonging to the first and fifth quintiles., Results: After the second dose of vaccine, the median circulating levels of anti-RBD IgG were significantly higher in HD (1456 AU/mL) compared to RTx (27.30 AU/mL). IGRA test showed significantly higher values in the HD (382 mIU/mL) compared with the RTx (73 mIU/mL). After the booster, humoral response increased significantly in both HD (p = 0.0002) and RTx groups (p = 0.009), whereas the T-cellular immunity remained essentially stable in most patients. In RTx patients with a low humoral response after the second dose, the third dose did not significantly strengthen either humoral or cellular immunity., Conclusions: For HD and RTx, there is great variability in the humoral response to anti-COVID-19 vaccination, with a stronger response in the HD group. The booster dose was ineffective at reinforcing the humoral and cellular immune response in most RTx patients hyporesponsive to the second dose., (© 2023. The Author(s), under exclusive licence to The Japanese Society of Nephrology.)

IgA nephropathy (IgAN) is a frequent cause of chronic kidney disease (CKD) and progressive renal impairment. A native renal biopsy diagnosis of IgAN is a predictor of graft loss, with a relative risk of 47% but it is difficult to predict graft survival and progressive allograft dysfunction in these patients. Deletion of complement factor H-related genes 1 and 3 (delCFHR3-1) has been associated with a decreased risk of developing IgAN on native kidneys, but the impact on the graft in IgAN-transplanted patients is unknown. We hypothesized that delCFHR3-1 is also associated with the processes that influence graft survival in transplant recipients with IgAN and tested whether cellular senescence is involved in mediating graft damage. We found that patients carrying two copies of CFHR1-3 had a worse outcome (P = .000321) and presented increased FHR1 deposits at glomerular and tubulointerstitial level associated with higher expression of the senescence marker p16 INK4a (P = .001) and tubulointerstitial fibrosis (P = .005). Interestingly, FHR1 deposits were associated with increased complement activation as demonstrated by C5b-9 deposits. These data support both the role of FHR1 in mediating complement activation and tubular senescence, and suggest the possibility of genotyping delCFHR3-1 to predict graft survival in IgAN-transplanted patients., (© 2020 The American Society of Transplantation and the American Society of Transplant Surgeons.)