The aim of this investigation was to determine the effect of SARS-Cov-2 vaccination in hemodialysis patients, search for risk factors for non- or low-response, and to measure the effect of a third booster vaccination in non- or low-responders. Methods SARS-CoV-2 IgG antibodies and the virus-neutralizing capacity were measured 4–5 weeks after a full standard vaccination in 95 chronic hemodialysis patients and 60 controls. IgG titers > 30 AU/mL served to classify participants as responders. Multivariable binary logistic regression analysis was used to search for risk factors of reduced vaccination success. Patients with vaccination failure were offered a third booster dosage. Results 82.1% of the patient cohort as compared to 98.3% of the healthy control group were able to mount SARS-CoV-2 titers above 30 AU/mL after two standard vaccine doses. Mean IgG antibody titers were lower in hemodialysis patients than controls (78 ± 35 vs. 90 ± 20 AU/mL, p = 0.002). Multivariable binary logistic regression analysis showed age and immunosuppressive medication as major risk factors for vaccination failure with a decreased probability of successful vaccination of −6.1% (95% CI −1.2 to −10.9) per increase in age of one year and −87.4% (95% CI −98.0 to −21.5) in patients on immunosuppressive therapy (crude odds ratio for vaccination failure for immunosuppressive therapy 6.4). Ten out of 17 patients with non-response to vaccination were offered a third dose. Booster vaccination after the second dose induced an increase in effective antibody titers of >30 AU/mL in seven out of ten patients 4–5 weeks later (70%). Conclusion Standard SARS-CoV-2 vaccination schemes are highly effective in mounting protective neutralizing IgG antibodies in chronic hemodialysis patients. Nevertheless, response to vaccination is diminished as compared to a healthy control group. Major risk factors for vaccination failure are older age and immunosuppressive therapy. In non- or low-responders to standard vaccination a third booster vaccination was able to induce effective antibody titers in about 70% of patients, indicating that a third booster vaccination might be preferable to decreasing immunosuppressive therapy.

Summary After the introduction of steroid sparing immunosuppressive protocols, osteonecrosis of the hip has become a rare entity in renal transplantation. Instead, an elusive bilateral pain syndrome of the distal extremities has gained more clinical attention. Because of the typical presentation, it is sometimes referred to as ‘post‐transplant distal limb syndrome’ (PTDLS). The syndrome typically manifests during the first year after transplantation and may lead to significant morbidity because of pain induced immobilization. On MRI‐scans, a characteristic bilateral patchy osteoedema can be demonstrated. The etiology of PTDLS has not been determined definitely so far. Over the last 8 years, we have seen the syndrome in 37 out of 639 renal transplant patients (5.8%). There was no association to steroid‐medication, age, gender, PTH levels or delayed graft function. As an important finding, we saw a significant rise in alkaline phosphatase from 160 ± 54 to 271 ± 108 U/l (P = 0.001) and calcium from 2.46 ± 0.18 to 2.58 ± 0.18 mmol/l (P = 0.013) preceding the onset of pain by several weeks. Mean duration of clinical symptoms was 5.1 ± 3.1 months; however, all patients experienced remission without signs of chronic damage on long‐term follow up.

There is a high incidence of latent pre-diabetes among renal transplant recipients. Increasing age, rejection episodes and lower diastolic blood pressure proved to be associated with pre-diabetes. In contrast to post-transplant diabetes, tacrolimus use and HbA1-c levels were not prognostic of pre-diabetes.

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