Using machine learning to predict antibody response to SARS-CoV-2 vaccination in solid organ transplant recipients: the multicentre ORCHESTRA cohort.

OBJECTIVES: The study aim was to assess predictors of negative antibody response (AbR) in solid organ transplant (SOT) recipients after the first booster of SARS-CoV-2 vaccination. METHODS: Solid organ transplant recipients receiving SARS-CoV-2 vaccination were prospectively enrolled (March 2021-January 2022) at six hospitals in Italy and Spain. AbR was assessed at first dose (t0), second dose (t1), 3 ± 1 month (t2), and 1 month after third dose (t3). Negative AbR at t3 was defined as an anti-receptor binding domain titre <45 BAU/mL. Machine learning models were developed to predict the individual risk of negative (vs. positive) AbR using age, type of transplant, time between transplant and vaccination, immunosuppressive drugs, type of vaccine, and graft function as covariates, subsequently assessed using a validation cohort. RESULTS: Overall, 1615 SOT recipients (1072 [66.3%] males; mean age±standard deviation [SD], 57.85 ± 13.77) were enrolled, and 1211 received three vaccination doses. Negative AbR rate decreased from 93.66% (886/946) to 21.90% (202/923) from t0 to t3. Univariate analysis showed that older patients (mean age, 60.21 ± 11.51 vs. 58.11 ± 13.08), anti-metabolites (57.9% vs. 35.1%), steroids (52.9% vs. 38.5%), recent transplantation (<3 years) (17.8% vs. 2.3%), and kidney, heart, or lung compared with liver transplantation (25%, 31.8%, 30.4% vs. 5.5%) had a higher likelihood of negative AbR. Machine learning (ML) algorithms showing best prediction performance were logistic regression (precision-recall curve-PRAUC mean 0.37 [95%CI 0.36-0.39]) and k-Nearest Neighbours (PRAUC 0.36 [0.35-0.37]). DISCUSSION: Almost a quarter of SOT recipients showed negative AbR after first booster dosage. Unfortunately, clinical information cannot efficiently predict negative AbR even with ML algorithms.

Relationship Between Immune Response to Severe Acute Respiratory Syndrome Coronavirus 2 Vaccines and Development of Breakthrough Infection in Solid Organ Transplant Recipients: The CONTRAST Cohort.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in solid organ transplant (SOT) recipients is associated with poorer antibody response (AbR) compared with non-SOT recipients. However, its impact on the risk of breakthrough infection (BI) has yet to be assessed. METHODS: Single-center prospective longitudinal cohort study enrolling adult SOT recipients who received SARS-CoV-2 vaccination during a 1-year period (February 2021 - January 2022), end of follow-up April 2022. Patients were tested for AbR at multiple time points. The primary end-point was BI (laboratory-confirmed SARS-CoV-2 infection ≥14 days after the second dose). Immunization (positive AbR) was considered an intermediate state between vaccination and BI. Probabilities of being in vaccination, immunization, and BI states were obtained for each type of graft and vaccination sequence using multistate survival analysis. Then, multivariable logistic regression was performed to analyze the risk of BI related to AbR levels. RESULTS: 614 SOT (275 kidney, 163 liver, 137 heart, 39 lung) recipients were included. Most patients (84.7%) received 3 vaccine doses. The first 2 consisted of BNT162b2 and mRNA-1273 in 73.5% and 26.5% of cases, respectively. For the third dose, mRNA-1273 was administered in 59.8% of patients. Overall, 75.4% of patients reached immunization and 18.4% developed BI. Heart transplant recipients showed the lowest probability of immunization (0.418) and the highest of BI (0.323); all mRNA-1273 vaccine sequences showed the highest probability of immunization (0.732) and the lowest of BI (0.098). Risk of BI was higher for non-high-level AbR, younger age, and shorter time from transplant. CONCLUSIONS: SOT patients with non-high-level AbR and shorter time from transplantation and heart recipients are at highest risk of BI.

Evaluation of the Kinetics of Antibody Response to COVID-19 Vaccine in Solid Organ Transplant Recipients: The Prospective Multicenter ORCHESTRA Cohort.

Previous studies assessing the antibody response (AbR) to mRNA COVID-19 vaccines in solid organ transplant (SOT) recipients are limited by short follow-up, hampering the analysis of AbR kinetics. We present the ORCHESTRA SOT recipients cohort assessed for AbR at first dose (t0), second dose (t1), and within 3 ± 1 month (t2) after the first dose. We analyzed 1062 SOT patients (kidney, 63.7%; liver, 17.4%; heart, 16.7%; and lung, 2.5%) and 5045 health care workers (HCWs). The AbR rates in the SOTs and HCWs were 52.3% and 99.4%. The antibody levels were significantly higher in the HCWs than in the SOTs (p < 0.001). The kinetics showed an increase (p < 0.001) in antibody levels up to 76 days and a non-significant decrease after 118 days in the SOT recipients versus a decrease up to 76 days (p = 0.02) and a less pronounced decrease between 76 and 118 days (p = 0.04) in the HCWs. Upon multivariable analysis, liver transplant, ≥3 years from SOT, mRNA-1273, azathioprine, and longer time from t0 were associated with a positive AbR at t2. Older age, other comorbidities, mycophenolate, steroids, and impaired graft function were associated with lower AbR probability. Our results may be useful to optimize strategies of immune monitoring after COVID-19 vaccination and indications regarding timing for booster dosages calibrated on SOT patients' characteristics.

COVID-19 in liver transplant candidates: pretransplant and post-transplant outcomes - an ELITA/ELTR multicentre cohort study.

OBJECTIVE: Explore the impact of COVID-19 on patients on the waiting list for liver transplantation (LT) and on their post-LT course. DESIGN: Data from consecutive adult LT candidates with COVID-19 were collected across Europe in a dedicated registry and were analysed. RESULTS: From 21 February to 20 November 2020, 136 adult cases with laboratory-confirmed SARS-CoV-2 infection from 33 centres in 11 European countries were collected, with 113 having COVID-19. Thirty-seven (37/113, 32.7%) patients died after a median of 18 (10-30) days, with respiratory failure being the major cause (33/37, 89.2%). The 60-day mortality risk did not significantly change between first (35.3%, 95% CI 23.9% to 50.0%) and second (26.0%, 95% CI 16.2% to 40.2%) waves. Multivariable Cox regression analysis showed Laboratory Model for End-stage Liver Disease (Lab-MELD) score of ≥15 (Model for End-stage Liver Disease (MELD) score 15-19, HR 5.46, 95% CI 1.81 to 16.50; MELD score≥20, HR 5.24, 95% CI 1.77 to 15.55) and dyspnoea on presentation (HR 3.89, 95% CI 2.02 to 7.51) being the two negative independent factors for mortality. Twenty-six patients underwent an LT after a median time of 78.5 (IQR 44-102) days, and 25 (96%) were alive after a median follow-up of 118 days (IQR 31-170). CONCLUSIONS: Increased mortality in LT candidates with COVID-19 (32.7%), reaching 45% in those with decompensated cirrhosis (DC) and Lab-MELD score of ≥15, was observed, with no significant difference between first and second waves of the pandemic. Respiratory failure was the major cause of death. The dismal prognosis of patients with DC supports the adoption of strict preventative measures and the urgent testing of vaccination efficacy in this population. Prior SARS-CoV-2 symptomatic infection did not affect early post-transplant survival (96%).

From advanced disease to transplantation: an overview of the liver at the time of COVID-19 pandemic.

In 2020, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also known as coronavirus disease 2019 (COVID-19) disrupted global health, causing hundreds of thousands of deaths worldwide. The liver injury appears to be one of the possible systemic manifestations of COVID-19 disease although the mechanisms causing such injury are not entirely clear. At the beginning of the pandemic, patients with chronic diseases, such as liver cirrhosis, or special populations, such as liver transplant recipients, were considered at higher risk of complications and poor clinical outcomes. Thus, the national transplant programmes have been severely hampered by the COVID-19 pandemic. Furthermore, liver transplant patients are potentially more vulnerable to SARS-CoV-2 infection due to immune suppression, ageing, and metabolic or cardiovascular comorbidities. This review analyses the increasing amounts of data collected in recent months concerning liver cirrhosis and liver transplants to understand if this finding is still relevant with respect to COVID-19 manifestations.

Liver transplantation in Italy in the era of COVID 19: reorganizing critical care of recipients.

Transplant programs have been severely disrupted by the COVID-19 pandemic. Italy was one of the first countries with the highest number of deaths in the world due to SARS-CoV-2. Here we propose a management model for the reorganization of liver transplant (LT) activities and policies in a local intensive care unit (ICU) assigned to liver transplantation affected by restrictions on mobility and availability of donors and recipients as well as health personnel and beds. We describe the solutions implemented to continue transplantation activities throughout a given pandemic: management of donors and recipients' LT program, ICU rearrangement, healthcare personnel training and monitoring to minimize mortality rates of patients on the waiting list. Transplantation activities from February 22, 2020, the data of first known COVID-19 case in Italy's Emilia Romagna region to June 30, 2020, were compared with the corresponding period in 2019. During the 2020 study period, 38 LTs were performed, whereas 41 were performed in 2019. Patients transplanted during the COVID-19 pandemic had higher MELD and MELD-Na scores, cold ischaemia times, and hospitalization rates (p < 0.05); accordingly, they spent fewer days on the waitlist and had a lower prevalence of hepatocellular carcinoma (p < 0.05). No differences were found in the provenance area, additional MELD scores, age of donors and recipients, BMI, re-transplant rates, and post-transplant mortality. No transplanted patients contracted COVID-19, although five healthcare workers did. Ultimately, our policy allowed us to continue the ICU's operations by prioritizing patients hospitalized with higher MELD without any case of transplant infection due to COVID-19.

COVID-19 in an international European liver transplant recipient cohort.

OBJECTIVE: Knowledge on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in liver transplant recipients is lacking, particularly in terms of severity of the disease. The aim of this study was to describe the demographic, baseline clinical characteristics and early outcomes of a European cohort of liver transplant recipients with SARS-CoV-2 infection. DESIGN: We conducted an international prospective study across Europe on liver transplant recipients with SARS-CoV-2 infection confirmed by microbiological assay during the first outbreak of COVID-19 pandemic. Baseline characteristics, clinical presentation, management of immunosuppressive therapy and outcomes were collected. RESULTS: 57 patients were included (70% male, median (IQR) age at diagnosis 65 (57-70) years). 21 (37%), 32 (56%) and 21 (37%) patients had one cardiovascular disease, arterial hypertension and diabetes mellitus, respectively. The most common symptoms were fever (79%), cough (55%), dyspnoea (46%), fatigue or myalgia (56%) and GI symptoms (33%). Immunosuppression was reduced in 22 recipients (37%) and discontinued in 4 (7%). With this regard, no impact on outcome was observed. Forty-one (72%) subjects were hospitalised and 11 (19%) developed acute respiratory distress syndrome. Overall, we estimated a case fatality rate of 12% (95% CI 5% to 24%), which increased to 17% (95% CI 7% to 32%) among hospitalised patients. Five out of the seven patients who died had a history of cancer. CONCLUSION: In this European multicentre prospective study of liver transplant recipients, COVID-19 was associated with an overall and in-hospital fatality rate of 12% (95% CI 5% to 24%) and 17% (95% CI 7% to 32%), respectively. A history of cancer was more frequent in patients with poorer outcome.