ABSTRACT
The proportion of pediatric cases with severe acute hepatitis of unknown etiology in the coronavirus disease 2019 era was higher than that in the pre-coronavirus disease 2019 era in Japan's largest pediatric transplant center. Further research and monitoring are essential.
Subject(s)
COVID-19 , Hepatitis , Liver Transplantation , Child , Humans , Liver Transplantation/adverse effects , Japan , Hepatitis/etiologyABSTRACT
Standardization of immunomodulation protocols has enabled ABO-incompatible liver transplants with outcomes similar to those of ABO-compatible liver transplants. Patients with the A2 blood group are unique because they have a diminished expression of the A antigen. Despite rare immune complications, this phenomenon of diminished expression has led to treatment of type A2 donors according to the regimen for type O blood group donors in ABO-incompatible liver transplants. Additionally, the requirement for pretransplant recipient immunomodulation is consi dered minimal when considering these donors. The transplant of a type A2 donor kidney to a type B recipient is well recognized; however, for liver donation the A2-to-B transplant is rare. Here, we present a case of 48-year-old male patient with blood group type B who underwent ABO-incompatible liver transplant of a right lobe liver graft from a type A2 donor. Postoperatively, despite adequate immunosuppression and initiation of thera - peutic plasma exchange, the patient developed severe and refractory antibody-mediated rejection that ultimately abated with a splenectomy. This report highlights the low but tangible risk of antibody-mediated rejection in ABO-incompatible liver transp lants from type A2 donors and emphasizes the importance of serial monitoring of anti-A isohemag glutinin titers and posttransplant splenectomy to ensure that liver grafts with antibody-mediated rejection can be rescued.
Subject(s)
Kidney Transplantation , Liver Transplantation , ABO Blood-Group System , Blood Group Incompatibility , Graft Rejection , Graft Survival , Humans , Immunosuppressive Agents/adverse effects , Kidney Transplantation/adverse effects , Liver Transplantation/adverse effects , Living Donors , Male , Middle Aged , Treatment OutcomeABSTRACT
The coronavirus disease-2019 (COVID-19) pandemic has had a large impact on patients with chronic liver disease (CLD) and liver transplantation (LT) recipients. Patients with advanced CLD are at a significantly increased risk of poor outcomes in the setting of severe acute respiratory syndrome coronavirus 2 infection. The pandemic has also considerably altered the management and care that is provided to patients with CLD, pre-LT patients, and LT recipients. Vaccination against COVID-19 protects patients with CLD and LT recipients from adverse outcomes and is safe in these patients; however, vaccine efficacy may be reduced in LT recipients and other immunosuppressed patients.
Subject(s)
COVID-19 , Coronavirus , Liver Transplantation , Humans , Liver Transplantation/adverse effects , Liver , Transplant RecipientsABSTRACT
Abnormal liver tests are common after liver transplantation. The differential diagnosis depends on the clinical context, particularly the time course, pattern and degree of elevation, and donor and recipient factors. The perioperative period has distinct causes compared with months and years after transplant, including ischemia-reperfusion injury, vascular thrombosis, and primary graft nonfunction. Etiologies seen beyond the perioperative period include biliary complications, rejection, infection, recurrent disease, and non-transplant-specific causes. The evaluation begins with a liver ultrasound with Doppler as well as appropriate laboratory testing and culminates in a liver biopsy if the imaging and laboratory testing is unrevealing.
Subject(s)
Liver Transplantation , Humans , Liver Transplantation/adverse effects , Liver Transplantation/methods , Postoperative Complications/diagnosis , Liver Function Tests , Tissue Donors , Liver/diagnostic imaging , Liver/pathologyABSTRACT
BACKGROUND: Liver transplantation is a proven management method for end-stage cirrhosis and is estimated to have increased life expectancy by 15 years. The COVID-19 pandemic posed a challenge to patients who were candid for a solid-organ transplant. It has been suggested that the outcomes of liver transplants could be adversely affected by the infection, as immunosuppression makes liver transplant candidates more susceptible to adverse effects while predisposing them to higher thrombotic events. MATERIAL AND METHODS: In this retrospective study, the cases who received liver transplants from January 2018 to March 2022 were assessed regarding early postoperative mortality rate and hepatic artery thrombosis (HAT) with COVID-19 infection. This study included 614 cases, of which 48 patients were infected. RESULTS: This study shows that the early COVID-19-related early postoperative mortality rates substantially increased in the elective setting (OR: 2.697), but the results for the acute liver failure were insignificant. The average model for end-stage liver disease score increased significantly during the pandemic due to new regulations. Although mortality rates increased during the pandemic, the data for the vaccination period show that mortality rates have equalised with the prepandemic era. Meanwhile, COVID-19 infection is assumed to have increased HAT by 1.6 times in the elective setting. CONCLUSION: This study shows that COVID-19 infection in an acute liver failure poses comparatively little risk; hence transplantation should be considered in such cases. Meanwhile, the hypercoagulative state induced by the infection predisposes this group of patients to higher HAT rates.
Subject(s)
COVID-19 , End Stage Liver Disease , Liver Failure, Acute , Liver Transplantation , Thrombosis , Humans , Liver Transplantation/adverse effects , COVID-19/epidemiology , Retrospective Studies , End Stage Liver Disease/epidemiology , End Stage Liver Disease/surgery , Pandemics , Severity of Illness Index , Liver Failure, Acute/etiology , Thrombosis/epidemiology , Thrombosis/etiologyABSTRACT
Worsened by the COVID-19 pandemic, alcohol use is one of the leading causes of preventable death in the US, in large part due to alcohol-associated liver disease. Throughout history, liver transplantation for this population has been controversial, and many policies and regulations have existed to limit access to lifesaving transplant for patients who use alcohol. In recent years, the rates of liver transplantation for patients with alcohol-associated liver disease have increased dramatically; however, disparities persist. For instance, many criteria used in evaluation for transplant listing, such as social support and prior knowledge of the harms of alcohol use, are not evidence based and may selectively disadvantage patients with alcohol use disorder. In addition, few transplant providers have adequate training in the treatment of alcohol use disorder, and few transplant centers offer specialized addiction treatment. Finally, current approaches to liver transplantation would benefit from adopting principles of harm reduction, which have demonstrated efficacy in the realm of addiction medicine for years. As we look toward the future, we must emphasize the use of evidence-based measures in selecting patients for listing, ensure access to high-quality addiction care for all patients pretransplant and posttransplant, and adopt harm reduction beliefs to better address relapse when it inevitably occurs. We believe that only by addressing each of these issues will we be able to ensure a more equitable distribution of resources in liver transplantation for all patients.
Subject(s)
Alcoholism , COVID-19 , Liver Diseases, Alcoholic , Liver Transplantation , Humans , Alcoholism/complications , Alcoholism/epidemiology , Alcoholism/therapy , Liver Transplantation/adverse effects , Pandemics , COVID-19/epidemiology , Liver Diseases, Alcoholic/epidemiology , Liver Diseases, Alcoholic/surgery , Liver Diseases, Alcoholic/complicationsABSTRACT
BACKGROUND AND AIMS: We retrospectively assessed the clinical Pfizer's mRNA SARS-CoV-2 BNT162b2 vaccination outcomes and the serologic impact on liver transplant (LT) recipients. PATIENTS AND METHODS: One hundred and sixty-seven LT cases followed between March 1, 2020 and September 25, 2021, and were stratified into two groups: (1) 37 LT recipients after SARS-CoV-2 infection before vaccine era and (2) 130 LT recipients vaccinated with 2 doses without earlier SARS-CoV-2 exposure. Serum SARS-CoV-2 spike immunoglobulins (anti-S) were assessed 7 days following vaccination (Liaison assay). RESULTS: In addition to the 37 nonvaccinated cases (22.2% of total group) who experienced SARS-CoV-2 infection (34 symptomatic and 3 asymptomatic), another 8 vaccinated symptomatic recipients (4.8%) were infected (5 from the third and three from the fourth waves). Three of the 45 infected cases died (6.7%) before the vaccine program. Vaccinated group: of the 130 LT vaccinated recipients, 8 (6.2%) got infected postvaccination (added to the infected group) and were defined as clinical vaccine failure; 38 (29.2%) were serological vaccine failure (total failure 35.4%), and 64.6% cases were serological vaccine responders (anti-S≥19 AU/mL). Longer post-LT interval and lower consumption of immunosuppressants (steroids, FK506, and mycophenolate mofetil) correlated with favorable SARS-CoV-2 vaccine response. Mammalian target of rapamycin inhibitors improved vaccine outcomes associated with lower FK506 dosages and serum levels. Patients with anti-S levels <100 AU/mL risked losing serologic response or being infected with SARS-CoV-2. A booster dose achieved an effective serologic response in a third of failures and most responders, securing better and possibly longer protection. CONCLUSION: Pfizer's BNT162b2 vaccine seems to lessen SARS-CoV-2 morbidity and mortality of LT recipients even with weak serological immunogenicity. Switching mycophenolate mofetil to mammalian target of rapamycin inhibitors might be effective before boosters in vaccine failure cases. A booster vaccine should be considered for nonresponders and low-responders after the second dose.
Subject(s)
COVID-19 , Liver Transplantation , Humans , COVID-19 Vaccines , BNT162 Vaccine , COVID-19/prevention & control , Liver Transplantation/adverse effects , Mycophenolic Acid , Retrospective Studies , Tacrolimus , SARS-CoV-2 , Cost of Illness , TOR Serine-Threonine KinasesABSTRACT
At the start of the pandemic, liver transplant recipients (LTR) were at high risk of developing severe COVID-19. Here, the outcomes of breakthrough infections in fully vaccinated LTR (n = 98) during the Omicron wave were assessed. In most patients, a mild disease course was observed, but 11 LTR (11.2%) required hospitalization for COVID-19-related complications. All patients survived. The LTR requiring hospitalization were older (67 years vs. 54 years; p < 0.001), had a higher Charlson comorbidity index (9 vs. 5; p < 0.001), and a lower anti-S RBD titer (Roche Elecsys) prior to infection (508.3 AU/mL vs. 2044 AU/mL; p = 0.03). Long-lasting symptoms for ≥4 weeks were reported by 37.5% of LTR (30/80). Risk factors in LTR included female sex (p = 0.01; Odds Ratio (OR) = 4.92 (95% confidence interval (CI) (1.5-16.5)) and dyspnea (p = 0.009; OR = 7.2 (95% CI (1.6-31.6)) during infection. Post-infection high anti-S RBD antibody levels were observed in LTR, and healthy controls (HC), while the cellular immune response, assessed by interferon-gamma release assay (EUROIMMUN), was significantly lower in LTR compared with HC (p < 0.001). In summary, in fully vaccinated LTR, SARS-CoV-2 breakthrough infections during the Omicron wave led to mild disease courses in the majority of patients and further boosted the humoral and cellular hybrid anti-SARS-CoV-2-directed immune response. While all patients survived, older and multimorbid LTR with low baseline antibody titers after vaccination still had a substantial risk for a disease course requiring hospitalization due to COVID-19-related complications.
Subject(s)
COVID-19 , Liver Transplantation , Humans , Female , Breakthrough Infections , Liver Transplantation/adverse effects , SARS-CoV-2 , Antibodies , Disease ProgressionABSTRACT
BACKGROUND Regular physical activity (PA) is important for maintaining mental and physical health after liver transplantation (LT); however, the fluctuations in routine PA during COVID-19 and its putative impacts are currently unknown. This study examined the changes in PA during the COVID-19 pandemic and explored its association with fear and depression during the pandemic. MATERIAL AND METHODS This longitudinal study included 83 LT patients whose PA was measured using the short form of the International Physical Activity Questionnaire before and during COVID-19. Fear of COVID-19 was estimated based on previous studies, and depression was assessed using the Patient Health Questionnaire-9. Participants were also asked about important sources of information on COVID-19. PA was classified as inactive or active depending on the changes in PA, and logistic regression analyses with PA as a dependent variable were conducted to explore the associations among PA, depression, and fear of COVID-19. RESULTS Moderate and high PA exhibited decreasing trends before and during the COVID-19 pandemic, especially in males. Fear of being infected with SARS-CoV-2, the virus that causes COVID-19, while shopping was significantly higher in females and was significantly independent of inactivity during the COVID-19 pandemic. Only 1 patient reported that their transplant center was their main source of information about COVID-19. Only 4.9% of the LT participants were depressed. CONCLUSIONS Our study results indicate the need to support the provision of accurate information about COVID-19 by health care professionals in transplant centers, especially for patients with low PA, to prevent PA decline in LT patients.
Subject(s)
COVID-19 , Liver Transplantation , Male , Female , Humans , COVID-19/epidemiology , Pandemics , SARS-CoV-2 , Liver Transplantation/adverse effects , Depression/epidemiology , Depression/etiology , Longitudinal Studies , Japan/epidemiology , Fear , Exercise , Surveys and QuestionnairesABSTRACT
A woman in her late 70s with a history of liver transplant presented with ophthalmoplegia, ataxia, areflexia, positive Babinski's sign and reduced consciousness. This followed an antecedent illness in the form of a herpes zoster infection. MRI of the brain/spinal cord, cerebrospinal fluid analysis with viral PCR and routine blood tests were normal, and tacrolimus neurotoxicity was ruled out. Serum anti-GQ1b antibodies were positive. A diagnosis of Bickerstaff's brainstem encephalitis was made, forming part of the continuum that involves Miller-Fisher syndrome, entitled the 'anti-GQ1b syndrome'. Complete recovery ensued without intravenous immunoglobulins or plasma exchange. The role of monitoring anti-ganglioside pattern change to predict or confirm disease recurrence and disease severity is further discussed.
Subject(s)
Encephalitis , Encephalomyelitis , Liver Transplantation , Miller Fisher Syndrome , Skin Diseases, Infectious , Female , Humans , Liver Transplantation/adverse effects , Brain Stem/diagnostic imaging , Miller Fisher Syndrome/diagnosis , Encephalitis/diagnosis , GangliosidesABSTRACT
Secondary sclerosing cholangitis in critically ill patients (SC-CIP) is a rare disease characterized by chronic cholestasis. The underlying pathophysiology of SC-CIP is not fully understood, and prognosis in severe cases remains poor with liver transplantation remaining the only curative treatment option. There is a growing amount of literature describing patients with chronic cholangiopathy after COVID-19 infection. The vast majority of the patients described in these reports were male and had a poor outcome. While the exact percentage of patients with COVID-19-related SC-CIP cannot be estimated accurately due to a lack of larger studies, an increase in patients with long-term complications of chronic cholestatic liver disease after severe COVID19-pneumonia can be expected in the upcoming years. Treatment options remain limited and further research is needed to improve the dismal prognosis of SC-CIP. Here, we present the cases of two patients who developed SC-CIP after prolonged intensive care unit stay due to severe COVID-19 pneumonia. Both patients required invasive ventilation for 31 and 141 days, respectively, as well as extra-corporal membrane oxygenation for 23 and 87 days. The patients suffered from jaundice and severe pruritus, and typical features of SC-CIP were present by MRCP and ERC. Repeated removal of biliary casts resulted in some alleviation of their clinical symptoms, but cholestasis parameters remain elevated. Furthermore, an increased liver stiffness was indicative of advanced fibrosis in both patients. In addition to these two case reports, we provide a concise review of the literature of SC-CIP after COVID-19 infection and discuss risk factors, treatment options and prognosis.
Subject(s)
COVID-19 , Cholangitis, Sclerosing , Cholestasis , Liver Transplantation , Humans , Male , Female , Cholangitis, Sclerosing/complications , Cholangitis, Sclerosing/diagnosis , COVID-19/complications , Critical Illness/therapy , Liver Transplantation/adverse effectsABSTRACT
OBJECTIVES: Coronavirus disease 2019 has resulted in significant morbidities and mortalities in nearly all parts ofthe world. There remain major concerns about management, timing, and safety of liver transplant in patients who have recovered from COVID-19. We aimed to study the clinical course and outcomes of patients with liver cirrhosis who recovered from COVID-19 and underwent liver transplant from deceased donors. MATERIALS AND METHODS: A retrospective study was conducted on liver transplant recipients who underwent liver transplant from April 1, 2020, to January 30, 2021. We evaluated all recipients of liver transplantfrom deceased donors during this period in the COVID-19 pandemic. RESULTS: There were 14 patients with decompensated liver cirrhosis who had recovered from COVID-19 as documented by reverse transcription-polymerase chain reaction test for SARS-CoV-2. Mean duration from COVID-19 to transplant surgery was 56.14 ± 29.96 days. Mortality occurred in 3 patients, and of whom 2 had been hospitalized and received medications for COVID-19 before transplant. Five patients had positive reverse transcription-polymerase chain reaction results for SARS-CoV-2 after liver transplant. CONCLUSIONS: This is a large reported series of patients with liver cirrhosis who have received liver transplant after recovery from COVID-19. We provided evidence that liver transplant from deceased donors should be considered in patients recovered from COVID-19, especially in those with deterioration of clinical status.
Subject(s)
COVID-19 , Liver Transplantation , Humans , Liver Transplantation/adverse effects , Liver Transplantation/methods , Retrospective Studies , Pandemics , Risk Factors , SARS-CoV-2 , Treatment Outcome , Liver Cirrhosis/diagnosis , Liver Cirrhosis/surgery , Liver Cirrhosis/etiologyABSTRACT
There is increasing incidence and prevalence of acute and chronic liver diseases (CLDs) all over the world which influence the quality of life and can give rise to life threatening complications. The burden of advanced liver disease due to hepatitis B has been controlled by antivirals but its eradication is difficult soon. Highly effective directly acting antiviral therapy has reduced the burden of hepatitis C but is partially offset by increasing IV drug abuse. Non-alcoholic fatty liver disease pandemic is on and there is recent alarming increase in alcohol related liver disease, both of which have no drug cure apart from control of the risk factors. Genetic factors have been identified in progression of all forms of CLD. Due to better management of complications of CLD, the life span of patients have increased spiking the number of hepatocellular carcinoma (HCC) and patients needing liver transplantation (LT). The present severe acute respiratory syndrome coronavirus pandemic has affected the outcome CLD including LT in addition to causing acute hepatitis. Better diagnostics and therapeutics are available for liver fibrosis, portal hypertension, HCC and post LT management and many drugs are under trial. The present review summarises the current scenario of the epidemiology and the advances in diagnosis and treatment of liver diseases including their complications like portal hypertension, HCC and LT.
Subject(s)
Carcinoma, Hepatocellular , Hypertension, Portal , Liver Neoplasms , Liver Transplantation , Non-alcoholic Fatty Liver Disease , Humans , Carcinoma, Hepatocellular/diagnosis , Carcinoma, Hepatocellular/epidemiology , Carcinoma, Hepatocellular/etiology , Liver Neoplasms/epidemiology , Liver Neoplasms/therapy , Liver Neoplasms/diagnosis , Quality of Life , Liver Transplantation/adverse effects , Liver Cirrhosis/pathology , Antiviral Agents/therapeutic use , Non-alcoholic Fatty Liver Disease/diagnosis , Non-alcoholic Fatty Liver Disease/epidemiology , Non-alcoholic Fatty Liver Disease/therapy , Hypertension, Portal/etiologyABSTRACT
BACKGROUND The incidence of abnormal liver function, mainly aspartate aminotransferase and alanine aminotransferase elevations, in patients with COVID-19 is not uncommon, but persistent liver damage after the acute phase of the disease is uncommon and has been recently recognized as a new entity named post-COVID-19 cholangiopathy. CASE REPORT We report a clinical case with progressive cholestatic disease following severe COVID-19. AST and ALT peaked at hospital admission and while its serum concentration went down, bilirubin and cholestatic liver enzymes started to increase, reaching the maximum at day 122. Magnetic resonance imaging (MRI) revealed a diffuse irregularity of intra- and extrahepatic bile ducts, with multiple focal strictures alternating with mild focal dilations of the biliary tree, suggesting a sclerosing cholangiopathy. A transjugular liver biopsy showed a prominent bile ductular reaction, cholangiocyte injury, inflammatory infiltrate rich in neutrophils, biliary infarctions, marked cholestasis, and portal fibrosis, suggesting the diagnosis of post-Covid-19 secondary sclerosing cholangitis. The patient evolved with a continuous deterioration of liver functions, but liver transplantation was not performed due to his poor clinical condition. CONCLUSIONS Post-COVID-19 SSC is a severe disease with no effective clinical treatment and has liver transplantation as the only treatment for a few selected patients.
Subject(s)
Bile Ducts, Extrahepatic , COVID-19 , Cholangitis, Sclerosing , Liver Transplantation , Bile Ducts, Extrahepatic/pathology , Cholangitis, Sclerosing/complications , Cholangitis, Sclerosing/diagnosis , Humans , Liver/pathology , Liver Transplantation/adverse effectsABSTRACT
BACKGROUND: Since January 2022, there has been an increase in reports of cases of acute hepatitis of unknown cause in children. Although cases have been reported across multiple continents, most have been reported in the United Kingdom. Investigations are ongoing to identify the causative agent or agents. METHODS: We conducted a retrospective study involving children referred to a single pediatric liver-transplantation center in the United Kingdom between January 1 and April 11, 2022. These children were 10 years of age or younger and had hepatitis that met the case definition of the U.K. Health Security Agency for confirmed acute hepatitis that was not hepatitis A through E and did not have a metabolic, inherited or genetic, congenital, or mechanical cause, in the context of a serum aminotransferase level greater than 500 IU per liter. We reviewed medical records and documented demographic characteristics, clinical features, and results of liver biochemical, serologic, and molecular tests for hepatotropic and other viruses, as well as radiologic and clinical outcomes. The outcomes were classified as an improving condition, liver transplantation, or death. RESULTS: A total of 44 children had hepatitis that met the confirmed case definition, and most were previously healthy. The median age was 4 years (range, 1 to 7). Common presenting features were jaundice (in 93% of the children), vomiting (in 54%), and diarrhea (in 32%). Among the 30 patients who underwent molecular testing for human adenovirus, 27 (90%) were positive. Fulminant liver failure developed in 6 patients (14%), all of whom received a liver transplant. None of the patients died. All the children, including the 6 who received liver transplants, were discharged home. CONCLUSIONS: In this series involving 44 young children with acute hepatitis of uncertain cause, human adenovirus was isolated in most of the children, but its role in the pathogenesis of this illness has not been established.
Subject(s)
Hepatitis , Liver Failure, Acute , Liver Transplantation , Acute Disease , Child , Child, Preschool , Hepatitis/etiology , Hepatitis/surgery , Humans , Infant , Liver Failure, Acute/etiology , Liver Failure, Acute/surgery , Liver Transplantation/adverse effects , Retrospective StudiesABSTRACT
Post-coronavirus disease 2019 (COVID-19) cholangiopathy (PCC) is a new entity observed in patients recovering from severe COVID-19 pneumonia. Most patients recover with cholestasis improving over a period of time. In some patients, cholestasis is severe and persists or progresses to liver failure necessitating liver transplant. We present a previously healthy 50-year-old man who developed PCC with peak total bilirubin of 42.4 mg/dl and did not improve with medical management. He underwent living donor auxiliary right lobe liver transplantation. He recovered well after transplant and remains asymptomatic at 6 months follow-up with good graft function and recovering function in native liver remnant.
Subject(s)
COVID-19 , Cholestasis , Liver Transplantation , Male , Humans , Middle Aged , Liver Transplantation/adverse effects , SARS-CoV-2 , Living DonorsABSTRACT
Personal protective equipment (PPE) comes in several variations, and is the principal safety gear during the COVID-19 pandemic. Unfortunately, the user is severely impacted by its serious nonergonomic features. What PPE is appropriate for labor-intensive cases, like liver transplant (LT), remains unknown. We describe our experience with 2 types of PPE used during 2 separate LT performed in COVID-19 positive recipients. We conclude that for the safety of both health care workers and patients, hospitals should designate a few PPE kits for labor-intensive surgical procedures. These kits should include powered air-purifying respirators, or a similar loose-fitting powered air hood.
Subject(s)
COVID-19 , Liver Transplantation , COVID-19/prevention & control , COVID-19 Testing , Health Personnel , Humans , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Liver Transplantation/adverse effects , Pandemics/prevention & control , Personal Protective Equipment , Polymerase Chain Reaction , SARS-CoV-2ABSTRACT
The Coronavirus Disease 2019 (COVID-19) pandemic has substantially impacted solid organ transplantation, including temporary inactivation of waitlist candidates with COVID-19 infection. We report two cases of liver transplantation (LT) in individuals with asymptomatic COVID-19 infection. The first patient is a 68-year-old female with decompensated cirrhosis complicated by worsening frailty and sarcopenia. The second patient is a 22-year-old female with acute liver failure likely secondary to drug/toxin exposure. Both patients were treated with COVID-19-directed therapies and neither patient developed symptomatic disease. These cases demonstrate that LT can be safely performed in select patients with asymptomatic COVID-19 infection at the time of transplant.