There are no studies which have compared the risk of severe Covid‐19 and related mortality between transplant recipients and non‐transplant patients. We enrolled two groups of patients hospitalized for Covid‐19, i.e., kidney transplant recipients from the French Registry of Solid Organ Transplant (n=306) and a single‐center cohort of non‐transplant patients (n=795). An analysis was performed among subgroups matched for age and risk factors for severe Covid‐19 or mortality. Severe Covid‐19 was defined as admission (or transfer) to an intensive care unit, need for mechanical ventilation, or death.Transplant recipients were younger and had more comorbidities compared to non‐transplant patients. They presented with higher creatinine levels and developed more episodes of acute kidney injury. After matching, the 30‐day cumulative incidence of severe Covid‐19 did not differ between KTR and non‐transplant patients; however, 30‐day Covid‐19‐related mortality was significantly higher in KTR (17.9% versus 11.4%, respectively, p=0.038). Age >60 years, cardiovascular disease, dyspnea, fever, lymphopenia, and C‐reactive protein (CRP) were associated with severe Covid‐19 in univariate analysis, whereas transplant status and serum creatinine levels were not. Age >60 years, hypertension, cardiovascular disease, diabetes, CRP >60 mg/L, lymphopenia, kidney transplant status (HR=1.55), and creatinine level >115 µmol/L (HR=2.32) were associated with Covid‐19‐related mortality in univariate analysis. In multivariable analysis, cardiovascular disease, dyspnea, and fever were associated with severe disease, whereas age >60 years, cardiovascular disease, dyspnea, fever, and creatinine level>115 µmol/L retained their independent associations with mortality. Kidney transplant recipients had a higher Covid‐19‐related mortality compared to non‐transplant hospitalized patients.

Significance Statement: Antibody and T cell responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines are poorly reported in kidney transplant recipients (KTRs) and patients on hemodialysis (HDPs). The authors investigated the response to BNT162b2 vaccine in 45 KTRs and ten HDPs. After the second dose, 88.9% of HDPs and only 17.8% of KTRs developed anti–SARS-CoV-2 antibodies. A specific T cell response was induced in 100% of HDPs and 57.8% of KTRs. The immune response seemed influenced by the immunosuppressive regimen in KTRs, particularly tacrolimus and belatacept. These results could help to better define the strategy of vaccination in this immunocompromised population. Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with a high rate of mortality in patients with ESKD, and vaccination is hoped to prevent infection. Methods: Between January 18 and February 24, 2021, 225 kidney transplant recipients (KTRs) and 45 patients on hemodialysis (HDPs) received two injections of mRNA BNT162b2 vaccine. The postvaccinal humoral and cellular response was explored in the first 45 KTRs and ten HDPs. Results: After the second dose, eight HDPs (88.9%) and eight KTRs (17.8%) developed antispike SARS-CoV-2 antibodies (P<0.001). Median titers of antibodies in responders were 1052 AU/ml (IQR, 515–2689) in HDPs and 671 AU/ml (IQR, 172–1523) in KTRs (P=0.40). Nine HDPs (100%) and 26 KTRs (57.8%) showed a specific T cell response (P=0.06) after the second injection. In responders, median numbers of spike-reactive T cells were 305 SFCs per 10⁶ CD3+ T cells (IQR, 95–947) in HDPs and 212 SFCs per 10⁶ CD3+ T cells (IQR, 61–330) in KTRs (P=0.40). In KTRs, the immune response to BNT162b2 seemed influenced by the immunosuppressive regimen, particularly tacrolimus or belatacept. Conclusion: Immunization with BNT162b2 seems more efficient in HDPs, indicating that vaccination should be highly recommended in these patients awaiting a transplant. However, the current vaccinal strategy for KTRs may not provide effective protection against COVID-19 and will likely need to be improved.

Immunosuppressed organ transplanted patients are considered at risk for severe forms of COVID‐19. Moreover, exaggerated innate and adaptive immune responses might be involved in severe progression of the disease. However, no data on the immune response to SARS‐CoV‐2 in transplanted patients is currently available. Here, we report the first assessment of antibody and T cell responses to SARS‐CoV‐2 in 11 kidney transplanted patients recovered from RT‐PCR‐confirmed (n=5) or initially suspected (n=6) COVID‐19. After reduction of immunosuppressive therapy, RT‐PCR‐confirmed COVID‐19 transplant patients were able to mount vigorous antiviral T cell and antibody responses, as efficiently as two non‐therapeutically immunosuppressed COVID‐19 patients on hemodialysis. By contrast, six RT‐PCR‐negative patients displayed no antibody response. Among them, three showed very low numbers of SARS‐CoV‐2‐reactive T cells whereas no T cell response was detected in the other three, potentially ruling out COVID‐19 diagnosis. Low levels of T cell reactivity to SARS‐CoV‐2 were also detected in seronegative healthy controls without known exposure to the virus. These results suggest that during COVID‐19, monitoring both T cell and serological immunity might be helpful for the differential diagnosis of COVID‐19 but are also needed to evaluate a potential role of antiviral T cells in the development of severe forms of the disease.

We report the case of a sensitized woman who underwent successful transplantation after a desensitization protocol, with an optically normal 8-day biopsy. At 3 months, she developed active antibody-mediated rejection (AMR) due to preformed donor-specific antibodies. It was decided to treat the patient with daratumumab, an anti-CD38 monoclonal antibody. The mean fluorescence intensity of donor-specific antibodies decreased, pathologic signs of AMR regressed, and kidney function returned to normal. A molecular assessment of biopsies was retrospectively performed. By doing so, regression of the molecular signature of AMR was evidenced between the second and third biopsies. Interestingly, the first biopsy revealed a gene expression profile of AMR, which helped retrospectively classify this biopsy as AMR, illustrating the relevance of molecular phenotyping of biopsy in high-risk situations such as desensitization.