SARS-CoV-2 Vaccination in Solid-Organ Transplant Recipients

Acceptance of Organs from Deceased Donors With Resolved or Active SARS-CoV-2 Infection: A Survey From the Council of Europe

SARS-CoV-2 infection represents a new challenge for solid organ transplantation (SOT) with evolving recommendations. A cross-sectional survey was performed (February-June 2024) to describe practices among Member States of the Council of Europe (COE) on the use of organs from deceased donors with resolved or active SARS-CoV-2 infection. Overall, 32 out of 47 Member States with a transplant program participated in the study. Four (12.5%) countries did not use organs from deceased donors either with resolved or with active SARS-CoV-2 infection and 8 (25%) countries accepted organs only from deceased donors with resolved SARS-CoV-2 infection. Donor evaluation for SARS-CoV-2 included universal screening with standard PCR testing on respiratory specimens generally (61.4%) performed within 24 h prior to organ recovery. Further microbiological, immunological and radiological investigations varied. Most waitlisted patients receiving organs from a deceased donor with active (94.5%) or resolved (61.5%) SARS-CoV-2 infection were preferred to have natural, vaccine-induced or hybrid SARS-CoV-2 immunity. Most countries did not require recipients to undergo specific anti-SARS-CoV-2 treatment as pre-exposure (0%), post-exposure prophylaxis (15.4%) or modification of immunosuppression regimen (24%). This study highlights similarities and heterogeneities in the management of SARS-CoV-2 positive donors between COE countries, and a potential to safely expand donors' pool.

Antibody response to non-mRNA SARS-CoV-2 vaccine in kidney transplant recipients

BACKGROUND

Kidney transplant recipients (KTRs) show poor antibody response to the SARS-CoV-2 vaccine. There is limited data on immune response to non-mRNA vaccines in KTRs. We studied the antibody response to the SARS-CoV-2 non-mRNA vaccine in a cohort of kidney transplant recipients.

METHODS

We included KTRs following up in the tertiary care transplant outpatient clinic from February to April 2022. SARS-CoV-2 spike protein IgG antibody titers were measured using chemiluminescence immunoassay. Data on demographic, clinical, and laboratory characteristics were collected, and patients were characterized by the history of Coronavirus disease 2019 (COVID-19) infection in the past and the number of vaccine doses received. Predictors of antibody response were obtained using multivariate regression analysis.

RESULTS

S1/S2 IgG anti-SARS-CoV-2 antibodies were detected in 197 (87.94%) of 224 KTRs with a median [IQR] titers of 307.5 AU/ml [91 AU/ml - 400 AU/ml]. Neutralizing range antibody titers were found in 170/224 (75.9%) KTRs. Diabetes at the time of vaccination was associated with poorer antibody response (aOR 0.31, 95% confidence interval [CI] - 0.10, 0.90; p = 0.032) and vaccination with Covishield™ (ChAdOx1 nCoV- 19 Recombinant CoronaVirus Vaccine) showed higher antibody response as compared to Covaxin™ (BBV152) (aOR 5.04, 95% CI - 1.56, 16.22; p = 0.007). Graft dysfunction at baseline was associated with poorer antibody response.

CONCLUSIONS

KTRs showed good antibody response after SARS-CoV-2 vaccination with non-mRNA vaccines. Diabetes and graft dysfunction were associated with poor seroconversion rates.

Risk factors for SARS-CoV-2 infection and severe COVID-19 in unvaccinated solid organ transplant recipients

The role of immunosuppressive therapy on SARS-CoV-2 infection risk and COVID-19 severity remains unclear in unvaccinated solid organ transplant recipients. We included 1957 organ transplant recipients between July 2020 and April 2021 to analyze whether baseline immunosuppressive therapy and other risk factors are associated with SARS-CoV-2 infection and severe COVID-19. In total, 247 (12.6%) had SARS-CoV-2 (defined as positive nasopharyngeal swab and/or positive antibody titer). Of these, 57 (23.1%) had severe COVID-19, defined as oxygen supplementation, intensive care unit admission or death. Multivariable analysis identified diabetes (hazard ratio (HR) 1.39 (95% confidence interval (CI) 1.05-1.83)), chronic lung disease (HR 1.71 (95% CI 1.13-2.60)) and contact with a COVID-19 positive individual (HR 3.61 (95% CI 2.61-4.99) as independent risk factors for SARS-CoV-2 infection. There was no association between immunosuppressive therapy and infection risk. Severe COVID-19 was multivariably associated with hypertension (OR 5.45 (95% CI 1.66-17.84)), chronic kidney disease (OR 3.55 (95% CI 1.75-7.19)), corticosteroid use (OR 2.93 (95% CI 1.03-2.55)) and having a COVID-19 positive housemate (OR 6.77 (95% CI 2.65-17.28)). In conclusion, baseline corticosteroid use, but no other immunosuppressive agent, is independently associated with severe COVID-19 in unvaccinated SOT recipients after correction for hypertension, chronic kidney disease, housemates affected by COVID-19 and transplant type.

Tixagevimab/cilgavimab prophylaxis against COVID-19 in solid organ transplant recipients: a systematic review and meta-analysis

Background

Tixagevimab/cilgavimab (Tix/Cil) shows promise as a prophylactic treatment against coronavirus disease 2019 (COVID-19) in solid organ transplant recipients (SOTRs). This study was performed to assess the effectiveness of Tix/Cil for preexposure prophylaxis against COVID-19 in this population.

Methods

We systematically searched the Cochrane Library, Web of Science, PubMed, and Embase databases to identify articles relevant to our study up to December 15, 2023. Comprehensive Meta-Analysis (ver. 3.0) was used for data analysis.

Results

The meta-analysis included seven eligible retrospective studies, encompassing a total of 4,026 SOTRs. The analysis revealed significant differences in SOTRs who received Tix/Cil preexposure prophylaxis relative to those who did not. Specifically, these differences were observed in the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (odds ratio [OR], 0.30; 95% confidence interval [CI], 0.15-0.60), hospitalization (OR, 0.24; 95% CI, 0.08-0.70), and intensive care unit admission (OR, 0.07; 95% CI, 0.02-0.22). However, mortality rate did not differ significantly between the two groups (P=0.06).

Conclusions

The evidence supporting the effectiveness of Tix/Cil as preexposure prophylaxis against SARS-CoV-2 in SOTRs is of a low to moderate level. Further high-quality research is necessary to understand its effects on this population.

Sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection among Kidney Transplant Recipients: A Large Single-Center Experience

BACKGROUND

Kidney transplant recipients (KTRs) are a vulnerable immunocompromised population at risk of severe COVID-19 disease and mortality after SARS-CoV-2 infection. We sought to characterize the post-infection sequelae in KTRs at our center.

METHODS

We studied all adult KTRs (with a functioning allograft) who had their first episode of SARS-CoV-2 infection between 04/2020 and 04/2022. Outcomes of interest included risk factors for hospitalization, all-cause mortality, COVID-19-related mortality, and allograft failure.

RESULTS

Of 979 KTRs with SARS-CoV-2 infection, 381 (39%) were hospitalized. In the multivariate analysis, risk factors for hospitalization included advanced age/year (HR: 1.03, 95% CI: 1.02-1.04), male sex (HR: 1.29, 95% CI: 1.04-1.60), non-white race (HR: 1.48, 95% CI: 1.17-1.88), and diabetes as a cause of ESKD (HR: 1.77, 95% CI: 1.41-2.21). SARS-CoV-2 Vaccination was associated with decreased risk of hospitalization (HR: 0.73, 95% CI: 0.59-0.90), all-cause mortality (HR: 0.52, 95% CI: 0.37-0.74), and COVID-19-related mortality (HR: 0.47, 95% CI: 0.31-0.71) in the univariate and multivariate analyses. Risk factors for both all-cause and COVID-19-related mortality in the multivariate analyses included advanced age, hospitalization, and respiratory symptoms for hospital admission. Furthermore, additional risk factors for all-cause mortality in the multivariate analysis included being a non-white recipient and diabetes as a cause of ESKD, with being a recipient of a living donor as protective.

CONCLUSIONS

Hospitalization due to COVID-19-associated symptoms is associated with increased mortality. Vaccination is a protective factor against hospitalization and mortality.

Incidence and Severity of COVID-19 in Relation to Anti-Receptor-Binding Domain IgG Antibody Level after COVID-19 Vaccination in Kidney Transplant Recipients

Kidney transplant recipients (KTRs) elicit an impaired immune response after COVID-19 vaccination; however, the exact clinical impact remains unclear. We therefore analyse the relationship between antibody levels after vaccination and the risk of COVID-19 in a large cohort of KTRs. All KTRs living in the Netherlands were invited to send a blood sample 28 days after their second COVID-19 vaccination for measurement of their IgG antibodies against the receptor-binding domain of the SARS-CoV-2 spike protein (anti-RBD IgG). Information on COVID-19 was collected from the moment the blood sample was obtained until 6 months thereafter. Multivariable Cox and logistic regression analyses were performed to analyse which factors affected the occurrence and severity (i.e., hospitalization and/or death) of COVID-19. In total, 12,159 KTRs were approached, of whom 2885 were included in the analyses. Among those, 1578 (54.7%) became seropositive (i.e., anti-RBD IgG level >50 BAU/mL). Seropositivity was associated with a lower risk for COVID-19, also after adjusting for multiple confounders, including socio-economic status and adherence to COVID-19 restrictions (HR 0.37 (0.19-0.47), p = 0.005). When studied on a continuous scale, we observed a log-linear relationship between antibody level and the risk for COVID-19 (HR 0.52 (0.31-0.89), p = 0.02). Similar results were found for COVID-19 severity. In conclusion, antibody level after COVID-19 vaccination is associated in a log-linear manner with the occurrence and severity of COVID-19 in KTRs. This implies that if future vaccinations are indicated, the aim should be to reach for as high an antibody level as possible and not only seropositivity to protect this vulnerable patient group from disease.

Sotrovimab in solid organ transplant recipients with COVID-19: a systematic review and meta-analysis

Background

Despite widespread implementation of vaccination against coronavirus disease 2019 (COVID-19), solid organ transplant recipients (SOTRs) can remain particularly vulnerable to this disease. The present study was conducted to investigate the efficacy and safety of sotrovimab in the treatment of SOTRs with COVID-19.

Methods

A search was performed of PubMed, Cochrane Library, Web of Science, medRxiv, and Google Scholar to gather relevant evidence through July 25, 2023. The quality of the included studies was assessed using the risk of bias tool. Comprehensive Meta-Analysis software (ver. 3.0, Biostat) was employed for data analysis.

Results

Ten studies, involving a total of 1,569 patients, were included. The meta-analysis revealed significant differences between the patients administered sotrovimab and those treated with the standard of care. These differences were observed in mortality rate (odds ratio [OR], 0.15; 95% confidence interval [CI], 0.03-0.67), hospitalization rate (OR, 0.35; 95% CI, 0.21-0.57), intensive care unit (ICU) admission rate (OR, 0.16; 95% CI, 0.04-0.62), the need for supplemental oxygen therapy (OR, 0.22; 95% CI, 0.09-0.51), and the need for mechanical ventilation (OR, 0.09; 95% CI, 0.01-0.70). However, no significant difference was observed between sotrovimab and other treatments regarding the rates of hospitalization or ICU admission (P>0.05). Regarding safety, sotrovimab was associated with a lower rate of adverse events compared to the absence of sotrovimab (OR, 0.15; 95% CI, 0.02-0.86).

Conclusions

These results suggest that sotrovimab may improve efficacy outcomes among SOTRs with COVID-19. Nevertheless, additional high-quality trials are necessary to confirm these findings.

Severity of COVID-19 Pneumonia in Kidney Transplant Recipients According to SARS-CoV-2 Vaccination

We reviewed 24 kidney transplantat recipients (KTRs) who had radiologically confirmed coronavirus disease 2019 (COVID-19) pneumonia. Enrolled KTRs were divided into a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-vaccination (+) group (n = 18) and a vaccination (-) group (n = 6). Clinical outcomes of the two groups including death, pulmonary outcome, and renal outcome were compared. COVID-19 pneumonia was worse in vaccination (-) KTRs. Two out of six vaccination (-) KTRs needed continuous renal replacement therapy (CRRT) and mechanical ventilator (MV) and expired. In contrast, only one KTR expired and required CRRT and MV out of 18 vaccination (+) KTRs. Our results suggest that SARS-CoV-2 vaccination attenuates severity of COVID-19 pneumonia in KTRs.

Differential cellular and humoral immune responses in immunocompromised individuals following multiple SARS-CoV-2 vaccinations

Introduction

The heterogeneity of the immunocompromised population means some individuals may exhibit variable, weak or reduced vaccine-induced immune responses, leaving them poorly protected from COVID-19 disease despite receiving multiple SARS-CoV-2 vaccinations. There is conflicting data on the immunogenicity elicited by multiple vaccinations in immunocompromised groups. The aim of this study was to measure both humoral and cellular vaccine-induced immunity in several immunocompromised cohorts and to compare them to immunocompetent controls.

Methods

Cytokine release in peptide-stimulated whole blood, and neutralising antibody and baseline SARS-CoV-2 spike-specific IgG levels in plasma were measured in rheumatology patients (n=29), renal transplant recipients (n=46), people living with HIV (PLWH) (n=27) and immunocompetent participants (n=64) post third or fourth vaccination from just one blood sample. Cytokines were measured by ELISA and multiplex array. Neutralising antibody levels in plasma were determined by a 50% neutralising antibody titre assay and SARS-CoV-2 spike specific IgG levels were quantified by ELISA.

Results

In infection negative donors, IFN-γ, IL-2 and neutralising antibody levels were significantly reduced in rheumatology patients (p=0.0014, p=0.0415, p=0.0319, respectively) and renal transplant recipients (p<0.0001, p=0.0005, p<0.0001, respectively) compared to immunocompetent controls, with IgG antibody responses similarly affected. Conversely, cellular and humoral immune responses were not impaired in PLWH, or between individuals from all groups with previous SARS-CoV-2 infections.

Discussion

These results suggest that specific subgroups within immunocompromised cohorts could benefit from distinct, personalised immunisation or treatment strategies. Identification of vaccine non-responders could be critical to protect those most at risk.

Humoral and T-cell response 12 months after the first BNT162b2 vaccination in solid organ transplant recipients and controls: Kinetics, associated factors, and role of SARS-CoV-2 infection

Introduction

We investigated humoral and T-cell responses within 12 months after first BNT162b2 vaccine in solid organ transplant (SOT) recipients and controls who had received at least three vaccine doses. Furthermore, we compared the immune response in participants with and without previous SARS-CoV-2 infection.

Methods

We included adult liver, lung, and kidney transplant recipients, and controls were selected from a parallel cohort of healthcare workers.

Results

At 12th-month, the IgG geometric mean concentrations (GMCs) (P<0.001), IgA GMCs (P=0.003), and median IFN-γ (P<0.001) were lower in SOT recipients than in controls. However, in SOT recipients and controls with previous infection, the neutralizing index was 99%, and the IgG, and IgA responses were comparable. After adjustment, female-sex (aOR: 3.6, P<0.009), kidney (aOR: 7.0, P= 0.008) or lung transplantation (aOR: 7.5, P= 0.014), and use of mycophenolate (aOR: 5.2, P=0.03) were associated with low IgG non response. Age (OR:1.4, P=0.038), time from transplantation to first vaccine (OR: 0.45, P<0.035), and previous SARS-CoV-2 infection (OR: 0.14, P<0.001), were associated with low IgA non response. Diabetes (OR:2.4, P=0.044) was associated with T-cell non response.

Conclusion

In conclusion, humoral and T-cell responses were inferior in SOT recipients without previous SARS-CoV-2 infection but comparable to controls in SOT recipients with previous infection.