COVID-19 in solid organ transplant recipients: A national cohort study from Sweden

COVID-19 Outcomes and Vaccinations in Swedish Solid Organ Transplant Recipients 2020-2021: A Nationwide Multi-Register Comparative Cohort Study

Increased COVID-19-related morbidity and mortality have been reported in solid organ transplant recipients (SOTRs). Most studies are underpowered for rigorous matching. We report infections, hospitalization, ICU care, mortality from COVID-19, and pertinent vaccination data in Swedish SOTRs 2020-2021. We conducted a nationwide cohort study, encompassing all Swedish residents. SOTRs were identified with ICD-10 codes and immunosuppressant prescriptions. Comparison cohorts were weighted based on a propensity score built from potential confounders (age, sex, comorbidities, socioeconomic factors, and geography), which achieved a good balance between SOTRs and non-SOTR groups. We included 10,372,033 individuals, including 9073 SOTRs. Of the SARS-CoV-2 infected, 47.3% of SOTRs and 19% of weighted comparator individuals were hospitalized. ICU care was given to 8% of infected SOTRs and 2% of weighted comparators. The case fatality rate was 7.7% in SOTRs, 6.2% in the weighted comparison cohort, and 1.3% in the unweighted comparison cohort. SOTRs had an increased risk of contracting COVID-19 (HR = 1.15 p < 0.001), being hospitalized (HR = 2.89 p < 0.001), receiving ICU care (HR = 4.59 p < 0.001), and dying (HR = 1.42 p < 0.001). SOTRs had much higher morbidity and mortality than the general population during 2020-2021. Also compared with weighted comparators, SOTRs had an increased risk of contracting COVID-19, being hospitalized, receiving ICU care, and dying. In Sweden, SOTRs were vaccinated earlier than weighted comparators. Lung transplant recipients had the worst outcomes. Excess mortality among SOTRs was concentrated in the second half of 2021.

COVID-19 Hospitalization in Solid Organ Transplant Recipients on Immunosuppressive Therapy

Importance

Solid organ transplant recipients are at high risk of severe infection with SARS-CoV-2 compared with the general population. However, factors associated with COVID-19-related severity in this population are still insufficiently explored in the literature.

Objective

To examine which health conditions and immunosuppressive drugs for preventing graft rejection are associated with the risk of COVID-19-related hospitalization in solid organ transplant recipients.

Design, Setting, and Participants

Using the French National Health Data System, this cohort study assessed patients of any age who received transplants between their date of birth and entry into the cohort on February 15, 2020. The cohort was followed up between February 15, 2020, and July 31, 2022.

Exposures

Immunosuppressive drugs, including steroids, and health conditions (age, sex, and comorbidities).

Main Outcomes and Measures

The main outcome was hospitalization for COVID-19, defined by main diagnostic International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes. Factors associated with the outcome were identified with a nonconditional logistic regression. Confounding by indication was controlled using a multivariable model with adjustment for individual confounders. Each transplanted organ was examined separately.

Results

Overall, 60 456 participants (median [IQR] age, 59 [47-67] years; 63.7% male) were included in the study, of whom 41 463 (68.6%) had kidney transplants, 14 464 (23.9%) had liver transplants, 5327 (8.8%) had heart transplants, and 2823 (4.6%) had lung transplants. Among them, 12.7% of kidney transplant recipients, 6.4% of liver transplant recipients, 12.9% of heart transplant recipients, and 18.0% of lung transplant recipients were hospitalized for COVID-19. In kidney transplant recipients, steroids (adjusted odds ratio [AOR], 1.60; 95% CI, 1.49-1.73) and mycophenolic acid (AOR, 1.37; 95% CI, 1.25-1.51) were associated with a high risk of hospitalization. In liver transplant recipients, tacrolimus (AOR, 0.77; 95% CI, 0.61-0.98) was associated with a decreased risk, and steroids (AOR, 1.60; 95% CI, 1.38-1.86) and mycophenolic acid (AOR, 1.61; 95% CI, 1.37-1.90) were associated with an increased risk of hospitalizations. In heart transplant recipients, cyclosporine (AOR, 0.67; 95% CI, 0.47-0.94) was associated with a decreased risk, and steroids (AOR, 1.42; 95% CI, 1.11-1.82), mycophenolic acid (AOR, 1.29; 95% CI, 1.02-1.64), sirolimus (AOR, 2.71; 95% CI, 1.20-6.09), and everolimus (AOR, 1.24; 95% CI, 1.01-1.51) were associated with an increased risk of hospitalization. Only steroids (AOR, 1.72; 95% CI, 1.19-2.48) were associated with a high risk of COVID-19 hospitalization in lung transplant recipients.

Conclusions and Relevance

This study suggests that mycophenolic acid, sirolimus, and steroids are associated with an increased risk of COVID-19-related hospitalization in solid organ transplant recipients. These results should be considered by clinicians treating transplant recipients and may help inform epidemic-related decisions for this population in the future.

Results of the first nationwide cohort study of outcomes in dialysis and kidney transplant patients before and after vaccination for COVID-19

BACKGROUND

Patients on kidney replacement therapy (KRT) have been identified as a vulnerable group during the coronavirus disease 2019 (COVID-19) pandemic. This study reports the outcomes of COVID-19 in KRT patients in Sweden, a country where patients on KRT were prioritized early in the vaccination campaign.

METHODS

Patients on KRT between January 2019 and December 2021 in the Swedish Renal Registry were included. Data were linked to national healthcare registries. The primary outcome was monthly all-cause mortality over 3 years of follow-up. The secondary outcomes were monthly COVID-19-related deaths and hospitalizations. The results were compared with the general population using standardized mortality ratios. The difference in risk for COVID-19-related outcomes between dialysis and kidney transplant recipients (KTRs) was assessed in multivariable logistic regression models before and after vaccinations started.

RESULTS

On 1 January 2020, there were 4097 patients on dialysis (median age 70 years) and 5905 KTRs (median age 58 years). Between March 2020 and February 2021, mean all-cause mortality rates increased by 10% (from 720 to 804 deaths) and 22% (from 158 to 206 deaths) in dialysis and KTRs, respectively, compared with the same period in 2019. After vaccinations started, all-cause mortality rates during the third wave (April 2021) returned to pre-COVID-19 mortality rates among dialysis patients, while mortality rates remained increased among transplant recipients. Dialysis patients had a higher risk for COVID-19 hospitalizations and death before vaccinations started {adjusted odds ratio [aOR] 2.1 [95% confidence interval (CI) 1.7-2.5]} but a lower risk after vaccination [aOR 0.5 (95% CI 0.4-0.7)] compared with KTRs.

CONCLUSIONS

The COVID-19 pandemic in Sweden resulted in increased mortality and hospitalization rates among KRT patients. After vaccinations started, a distinct reduction in hospitalization and mortality rates was observed among dialysis patients, but not in KTRs. Early and prioritized vaccinations of KRT patients in Sweden probably saved many lives.

COVID-19 in patients with liver disease and liver transplant: clinical implications, prevention, and management

The coronavirus disease 2019 (COVID-19) pandemic has had enormous implications for the care of patients with chronic liver disease (CLD), cirrhosis, and liver transplant (LT). Clinical outcomes of COVID-19 vary in patients with CLD and cirrhosis compared to healthy controls, and in patients with LT compared to patients without LT. Several special considerations apply to the approach to vaccination and treatment in patients with CLD and LT. The practice of liver transplantation has also been heavily impacted by the pandemic, including persistent reductions in living donor LT and increases in LT for an indication of alcohol-related liver disease. Recent medical society guidelines strive to standardize severe acute respiratory syndrome coronavirus 2 testing in donors and recipients and the approach to transplantation after recovered from COVID-19 infection, but certain controversies remain.

COVID-19 in solid organ transplant recipients after 2 years of pandemic: Outcome and impact of antiviral treatments in a single-center study

More than 2 years after the pandemic, the availability of vaccination and the use of monoclonal antibodies and direct antivirals have changed the fate of COVID-19, allowing for a better management of the disease, reducing hospitalization rates, and improving survival. This study aims to describe the outcome of COVID-19 in a cohort of solid organ transplant recipients and the impact of novel antivirals against SARS-CoV-2. We conducted an observational retrospective cohort study. We enrolled solid organ transplant recipients with COVID-19 attending the A.O.U. Federico II of Naples and followed up from January 2022 to July 2022. We enrolled 40 SOTs with COVID-19. Our experience highlights the favorable impact of therapies with antivirals and monoclonal antibodies in the early stages of COVID-19. Interesting data concern the impact of immunosuppressive therapy on COVID-19, in particular the role of Mycophenolate (associated with deterioration to severe COVID-19) and Everolimus (protective for progression to severe disease) needs to be investigated. Our experience also confirms the fundamental role of vaccination and in particular the importance of the booster dose.

Difference between SARS-CoV-2, seasonal coronavirus, influenza, and respiratory syncytial virus infection in solid organ transplant recipients

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been raging since the end of 2019 and has shown worse outcomes in solid organ transplant (SOT) recipients. The clinical differences as well as outcomes between respiratory viruses have not been well defined in this population.

METHODS

This is a retrospective cohort study of adult SOT recipients with nasopharyngeal swab or bronchoalveolar lavage PCR positive for either SARS-CoV-2, seasonal coronavirus, respiratory syncytial virus (RSV) or influenza virus from January 2017 to October 2020. The follow up period was 3 months. Clinical characteristics and outcomes were evaluated.

RESULTS

A total of 377 recipients including 157 SARS-CoV-2, 70 seasonal coronavirus, 50 RSV and 100 influenza infections were identified. The most common transplanted organ was kidney 224/377 (59.4%). Lower respiratory tract infection (LRTI) was found in 210/377 (55.7%) and the risk factors identified with multivariable analysis were SARS-CoV-2 infection, steroid use, and older age. Co- and secondary infections were seen in 77/377 (20.4%) recipients with bacterial pathogens as dominant. Hospital admission was seen in 266/377 (67.7%) recipients without significant statistical difference among viruses, however, ICU admission, mechanical ventilation and mortality were higher with SARS-CoV-2 infection. In the multivariable model, the risk factors for mortality were SARS-CoV-2 infection and older age.

CONCLUSIONS

We found higher incidence of ICU admission, mechanical ventilation, and mortality among SARS-CoV-2 infected recipients. Older age was found to be the risk factor for lower respiratory tract infection and mortality for SARS-CoV-2, coronaviruses, RSV and influenza virus groups.

Incidence and severity of SARS-CoV-2 infections in liver and kidney transplant recipients in the post-vaccination era: Real-life data from Denmark

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has been associated with a high risk of adverse outcomes in solid organ transplant (SOT) recipients in the pre-vaccination era. In this retrospective cohort study, we examined the incidence and severity of COVID-19 in kidney and liver transplant recipients in Denmark in the post-vaccination era, from December 27, 2020, to December 27, 2021. We included 1428 SOT recipients with 143 cases of first-positive SARS-CoV-2 PCR test. The cumulative incidence of first-positive SARS-CoV-2 PCR test 1 year after initiation of vaccination was 10.4% (95% CI: 8.8-12.0), and the incidence was higher in kidney than in liver transplant recipients (11.6% [95% CI: 9.4-13.8] vs. 7.4% [95% CI: 5.1-9.8], p = .009). After the first-positive SARS-CoV-2 PCR test, the hospitalization rate was 31.5% (95% CI: 23.9-39.1), and 30-day all-cause mortality was 3.7% (95% CI: 0.5-6.8). Hospitalization was lower in vaccinated than in unvaccinated SOT recipients (26.4% [95% CI: 18.1-34.6] vs. 48.5% [95% CI: 31.4-65.5], p = .011), as was mortality (1.8% [95% CI: 0.0-4.3] vs. 9.1% [95% CI: 0.0-18.9], p = .047). In conclusion, SOT recipients remain at high risk of adverse outcomes after SARS-CoV-2 infections, with a lower risk observed in vaccinated than in unvaccinated SOT recipients.

Can the COVID-19 Pandemic Improve the Management of Solid Organ Transplant Recipients?

Increased mortality due to SARS-CoV-2 infection was observed among solid organ transplant patients. During the pandemic, in order to prevent and treat COVID-19 infections in this context, several innovative procedures and therapies were initiated within a short period of time. A large number of these innovations can be applied and expanded to improve the management of non-COVID-19 infectious diseases in solid organ transplant patients and in the case of a future pandemic. In this vein, the present paper reviews and discusses medical care system adaptation, modification of immunosuppression, adjuvant innovative therapies, the role of laboratory expertise, and the prevention of infections as examples of such innovations.

Clinical Characteristics and Outcomes of Immunocompromised Patients With Coronavirus Disease 2019 Caused by the Omicron Variant: A Prospective, Observational Study

BACKGROUND

Illness after infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant is less severe compared with previous variants. Data on the disease burden in immunocompromised patients are lacking. We investigated the clinical characteristics and outcomes of immunocompromised patients with coronavirus disease 2019 (COVID-19) caused by Omicron.

METHODS

Organ transplant recipients, patients on anti-CD20 therapy, and allogenic hematopoietic stem cell transplantation recipients infected with the Omicron variant were included. Characteristics of consenting patients were collected and patients were contacted regularly until symptom resolution. To identify possible risk factors for hospitalization, a univariate logistic analysis was performed.

RESULTS

114 consecutive immunocompromised patients were enrolled. Eighty-nine percent had previously received 3 mRNA vaccinations. While only 1 patient died, 23 (20%) were hospitalized for a median of 11 days. A low SARS-CoV-2 immunoglobulin G (IgG) antibody response (<300 BAU [binding antibody units]/mL) at diagnosis, being older, being a lung transplant recipient, having more comorbidities, and having a higher frailty score were associated with hospital admission (all P < .01). At the end of follow-up, 25% had still not fully recovered. Of the 23 hospitalized patients, 70% had a negative and 92% had a low IgG (<300 BAU/mL) antibody response at admission. Sotrovimab was administered to 17 of these patients, and 1 died.

CONCLUSIONS

While the mortality in immunocompromised patients infected with Omicron was low, hospital admission was frequent and the duration of symptoms often prolonged. In addition to vaccination, other interventions are needed to limit the morbidity from COVID-19 in immunocompromised patients.

COVID-19 and kidney disease: insights from epidemiology to inform clinical practice

Over the course of the COVID-19 pandemic, numerous studies have aimed to address the challenges faced by patients with kidney disease and their caregivers. These studies addressed areas of concern such as the high infection and mortality risk of patients on in-centre haemodialysis and transplant recipients. However, the ability to draw meaningful conclusions from these studies has in some instances been challenging, owing to barriers in aspects of usual care, data limitations and problematic methodological practices. In many settings, access to SARS-CoV-2 testing differed substantially between patient groups, whereas the incidence of SARS-CoV-2 infection varied over time and place because of differences in viral prevalence, targeted public health policies and vaccination rates. The absence of baseline kidney function data posed problems in the classification of chronic kidney disease and acute kidney injury in some studies, potentially compromising the generalizability of findings. Study findings also require attentive appraisal in terms of the effects of confounding, collider bias and chance. As this pandemic continues and in the future, the implementation of sustainable and integrated research infrastructure is needed in settings across the world to minimize infection transmission and both prevent and plan for the short-term and long-term complications of infectious diseases. Registries can support the real-world evaluation of vaccines and therapies in patients with advanced kidney disease while enabling monitoring of rare complications.

COVID-19 Vaccination and Remdesivir are Associated With Protection From New or Increased Levels of Donor-Specific Antibodies Among Kidney Transplant Recipients Hospitalized With COVID-19

Alloimmune responses in kidney transplant (KT) patients previously hospitalized with COVID-19 are understudied. We analyzed a cohort of 112 kidney transplant recipients who were hospitalized following a positive SARS-CoV-2 test result during the first 20 months of the COVID-19 pandemic. We found a cumulative incidence of 17% for the development of new donor-specific antibodies (DSA) or increased levels of pre-existing DSA in hospitalized SARS-CoV-2-infected KT patients. This risk extended 8 months post-infection. These changes in DSA status were associated with late allograft dysfunction. Risk factors for new or increased DSA responses in this KT patient cohort included the presence of circulating DSA pre-COVID-19 diagnosis and time post-transplantation. COVID-19 vaccination prior to infection and remdesivir administration during infection were each associated with decreased likelihood of developing a new or increased DSA response. These data show that new or enhanced DSA responses frequently occur among KT patients requiring admission with COVID-19 and suggest that surveillance, vaccination, and antiviral therapies may be important tools to prevent alloimmunity in these individuals.

COVID-19 em receptores de transplante renal: o que aprendemos um ano depois? Um estudo de coorte a partir de um centro terciário

Resumo Introdução: Os receptores de transplante renal (TR) apresentam um alto risco para desfechos adversos de infecções, tais como a COVID-19. Métodos: Revisamos retrospectivamente todos os receptores de TR com COVID-19 documentada entre 1º de Março de 2020 e 15 de Março de 2021, e analisamos as características, curso clínico, tratamento e desfechos dos pacientes. Resultados: Identificamos 123 pacientes, 72% do sexo masculino, com uma média de idade de 54,5±13,0 anos. Vinte por cento eram assintomáticos, 7% apresentaram transmissão nosocomial, e 36% do restante necessitaram de internação. Quase todos os pacientes internados receberam oxigênio, 30% necessitaram de ventilação mecânica invasiva (VMI), mais da metade apresentou lesão renal aguda, com 10% necessitando de diálise, e 20% foram a óbito. A incidência foi comparável à da população portuguesa, mas a taxa de mortalidade foi quase quatro vezes superior (TMP de 3,768 (IC 95%: 1,723-7,154). Maior índice de massa corporal (OR 1,275; P=0,001), menor função do enxerto basal (OR 0,968; P=0,015), e transmissão nosocomial (OR 13,836; P=0,019) foram associados à demanda de oxigênio, enquanto sexo feminino (OR 3,801; P=0,031) e menor função do enxerto renal basal (OR 0,955; P=0,005), mas não índice de massa corporal, foram associados à VMI e/ou óbito. Conclusão: A taxa de mortalidade em pacientes com TR foi mais elevada do que na população em geral e a função renal basal mais baixa foi o marcador mais consistente para desfechos adversos.

An overview of COVID-19 in solid organ transplantation

BACKGROUND

The COVID-19 pandemic has influenced the field of solid organ transplantation (SOT) in many ways. COVID-19 has led to programmatic impacts and changes in donor and recipient selection. Several studies have evaluated the course, optimal treatment, and prevention of COVID-19 in SOT recipients.

OBJECTIVES

To review the literature on COVID-19 in SOT recipients.

SOURCES

PubMed, Web of Science, and Google Scholar were searched. The search was restricted to articles published between January 1, 2019 and December 1, 2021.

CONTENT

The COVID-19 pandemic initially led to a decreased volume of solid organ transplants. However, transplant volumes at most centres have rebounded. Donor selection remains an incompletely defined issue. Several reports suggest that donor-derived SARS-CoV-2 infections occur only in lung transplant recipients and that other organs from SARS-CoV-2 PCR-positive donors could potentially be safely used. However, these data are limited to case series. Transplantation for end-stage lung disease after COVID-19 infection is increasingly common and has been performed with acceptable outcomes. In acute COVID-19 in a transplant candidate, transplantation should be delayed when feasible. After adjustment, mortality after COVID-19 appear similar in SOT recipients compared to the general population, with notable increased use of antiviral and anti-inflammatory treatment options. Prevention of COVID-19 is key in SOT recipients. Vaccination of SOT recipients and anyone who is in contact with SOT recipients is one of the cornerstones of prevention. Nonpharmacological interventions such as face coverings, hand hygiene, and physical distancing remain ever important as well.

IMPLICATIONS

The COVID-19 pandemic continues to have an important impact on SOT candidates and recipients. Prevention of infection is the most important measure and requires careful attention to approaches to vaccination and messaging of the ongoing need for face coverings, physical distancing, and hand hygiene.

Potential importance of early treatment of SARS-CoV-2 infection in intestinal transplant patient: A case report

BACKGROUND

Predispositions for severe coronavirus disease 2019 (COVID-19) are age, immunosuppression, and co-morbidity. High levels of maintenance immunosuppression render intestinal transplant (ITx) patients vulnerable for severe COVID-19. COVID-19 also provokes several gastroenterological pathologies which have not been discussed in ITx, so far.

CASE SUMMARY

During the second European COVID-19 wave in November 2020, an ITx recipient was admitted to the hospital because of electrolyte disturbances due to dehydration. Immunosuppression consisted of tacrolimus, azathioprine, and low-dose corticosteroids. During hospitalization, she tested positive on screening COVID-19 nasopharyngeal polymerase chain reaction swab, while her initial test was negative. She was initially asymptomatic and had normal inflammatory markers. Tacrolimus levels were slightly raised, as Azathioprine was temporarily halted. Due to elevated D-dimers at that time, prophylactic low-molecular weight heparin was started. Seven days after the positive test, dyspnea, anosmia, and C-reactive protein increase (25 mg/L) were noted. Remdesivir was administered during 5 d in total. High stomal output was noted in two consecutive days and several days thereafter. To exclude infection or rejection, an ileoscopy and biopsy were performed and excluded these. Four weeks later, she was discharged from the hospital and remains in good health since then.

CONCLUSION

Early eradication of severe acute respiratory syndrome coronavirus 2 in ITx recipients may be warranted to prevent acute rejection provocation by it.

Longevity of anti-spike and anti-nucleocapsid antibodies after COVID-19 in solid organ transplant recipients compared to immunocompetent controls

Solid organ transplant recipients (SOTRs) are on lifelong immunosuppression, which may interfere with adaptive immunity to COVID-19. The data on dynamics and duration of antibody response in SOTRs are limited. This longitudinal study examined the longevity of both anti-spike (S)- and anti-nucleocapsid (N)-specific IgG antibodies after COVID-19 in SOTRs compared to matched immunocompetent persons. SOTRs (n = 65) were matched with controls (n = 65) for COVID-19 disease severity, age, and sex in order of priority. Serum-IgG antibodies against N and S antigens of SARS-CoV-2 were analyzed. At 1 and 9 months after COVID-19, anti-S-IgG detectability decreased from 91% to 82% in SOTRs versus 100% to 95% in controls, whereas the anti-N-IgG decreased from 63% to 29% in SOTRs versus 89% to 46% in controls. A matched paired analysis showed SOTRs having significantly lower levels of anti-N-IgG at all time points (1 month p = .007, 3 months p < .001, 6 months p = .019, and 9 months p = .021) but not anti-S-IgG at any time points. A mixed-model analysis confirmed these findings except for anti-S-IgG at 1 month (p = .005) and identified severity score as the most important predictor of antibody response. SOTRs mount comparable S-specific, but not N-specific, antibody responses to SARS-CoV-2 infection compared to immunocompetent controls.

Convalescent plasma treatment in severely immunosuppressed patients hospitalized with COVID-19: an observational study of 28 cases

BACKGROUND

Immunosuppressed patients are particularly vulnerable to severe infection from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), risking prolonged viremia and symptom duration. In this study we describe clinical and virological treatment outcomes in a heterogeneous group of patients with severe immunosuppression due to various causes suffering from COVID-19 infection, who were all treated with convalescent plasma (CCP) along with standard treatment.

METHODS

We performed an observational, retrospective case series between May 2020 to March 2021 at three sites in Skåne, Sweden, with a population of nearly 1.4 million people. All patients hospitalized for COVID-19 who received CCP with the indication severe immunosuppression as defined by the treating physician were included in the study (n = 28).

RESULTS

In total, 28 severely immunocompromised patients, half of which previously had been treated with rituximab, who had received in-hospital convalescent plasma treatment of COVID-19 were identified. One week after CCP treatment, 13 of 28 (46%) patients had improved clinically defined as a decrease of at least one point at the WHO-scale. Three patients had increased score points of whom two had died. For 12 patients, the WHO-scale was unchanged.

CONCLUSION

As one of only few studies on CCP treatment of COVID-19 in hospitalized patients with severe immunosuppression, this study adds descriptive data. The study design prohibits conclusions on safety and efficacy, and the results should be interpreted with caution. Prospective, randomized trials are needed to investigate this further.

Insufficient response to mRNA SARS-CoV-2 vaccine and high incidence of severe COVID-19 in kidney transplant recipients during pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination may fail to sufficiently protect transplant recipients against coronavirus disease 2019 (COVID-19). We retrospectively evaluated COVID-19 in kidney transplant recipients (n = 226) after BNT162b2 mRNA vaccine administration. The control group consisted of unvaccinated patients (n = 194) during the previous pandemic wave. We measured anti-spike protein immunoglobulin G (IgG) levels and cellular responses, using enzyme-linked immunosorbent spot assay, in a prospective cohort after vaccination (n = 31) and recovery from COVID-19 (n = 19). COVID-19 was diagnosed in 37 (16%) vaccinated and 43 (22%) unvaccinated patients. COVID-19 severity was similar in both groups, with patients exhibiting a comparable need for hospitalization (41% vs. 40%, p = 1.000) and mortality (14% vs. 9%, p = .726). Short posttransplant periods were associated with COVID-19 after vaccination (p < .001). Only 5 (16%) patients achieved positive SARS-CoV-2 IgG after vaccination, and 17 (89%, p < .001) recovered from COVID-19 (median IgG levels, 0.6 vs. 52.5 AU/ml, p < .001). A cellular response following vaccination was present in the majority (n = 22, 71%), with an increase in interleukin 2 secreting T cells (p < .001). Despite detectable T cell immunity after mRNA vaccination, kidney transplant recipients remained at a high risk of severe COVID-19. Humoral responses induced by vaccination were significantly lower than that after COVID-19.

Immunological Biomarkers in Blood to Monitor the Course and Therapeutic Outcomes of COVID-19

BACKGROUND

The COVID-19 pandemic has posed a great challenge to the medical community because little is known about its clinical course, therapeutic options, and laboratory monitoring tools for diagnosis, prognosis, and surveillance. This review focuses on immune biomarkers that can be measured in peripheral blood in a clinical laboratory under routine conditions to monitor the innate immune system response in the acute phase, as well as the adaptive immune response established both after infection and vaccination.

METHODS

A PubMed search was performed covering January 2020 to June 2021 to extract biomarkers suitable for monitoring the immune response and outcome of COVID-19 and therapeutic interventions, including vaccination.

RESULTS

To monitor the innate immune response, cytokines such as interleukin-6 or acute phase reactants such as C-reactive protein or procalcitonin can be measured on autoanalyzers complemented by automated white blood cell differential counts. The adaptive immune response can be followed by commercially available enzyme-linked immune spot assays to assess the specific activation of T cells or by monitoring immunoglobulin A (IgA), IgM, and IgG antibodies in serum to follow B-cell activation. As antigens of the SARS-CoV-2 virus, spike and nucleocapsid proteins are particularly suitable and allow differentiation between the immune response after infection or vaccination.

CONCLUSIONS

Routine immune monitoring of COVID-19 is feasible in clinical laboratories with commercially available instruments and reagents. Strategies such as whether biomarkers reflecting the response of the innate and adaptive immune system can be used to make predictions and assist in individualizing therapeutic interventions or vaccination strategies need to be determined in appropriate clinical trials. Promising preliminary data are already available based on single-center reports and completed or ongoing vaccination trials.

COVID-19 in kidney transplant recipients: what have we learned one year later? A cohort study from a tertiary center

INTRODUCTION

Kidney transplant (KT) recipients have a high risk for adverse outcomes from infections, such as COVID-19.

METHODS

We have retrospectively reviewed all KT recipients with documented COVID-19 between March 1, 2020, and March 15, 2021, and analyzed patients' characteristics, clinical course, treatment, and outcomes.

RESULTS

We identified 123 patients, 72% were male, with a mean age of 54.5±13.0 years. Twenty percent were asymptomatic, 7% had a nosocomial transmission, and 36% of the remainder required hospitalization. Almost all admitted patients received oxygen, 30% required invasive mechanical ventilation (IMV), more than a half had acute kidney injury, with 10% requiring dialysis, and 20% died. Incidence was comparable to that of the Portuguese population, but the mortality rate was almost four times higher (SMR of 3.768 (95% CI:1.723-7.154). Higher body mass index (OR 1.275, P=0.001), lower baseline graft function (OR 0.968, P=0.015), and nosocomial transmission (OR 13.836, P=0.019) were associated with oxygen demand, whereas female gender (OR 3.801, P=0.031) and lower baseline kidney graft function (OR 0.955, P=0.005), but not body mass index, were associated with IMV and/or death.

CONCLUSION

Mortality rate in KT patients was higher than in the general population and lower baseline kidney function was the most consistent marker for adverse outcomes.

Predictive Factors for Humoral Response After 2-dose SARS-CoV-2 Vaccine in Solid Organ Transplant Patients

Background

A weak immunogenicity has been reported in solid organ transplant (SOT) recipients after 2 doses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. The aim of this retrospective study was to identify the predictive factors for humoral response in SOT patients.

Methods

Three hundred and ninety-three SOT patients from our center with at least 4 wk of follow-up after 2 doses of mRNA-based vaccine were included in this study. Anti-SARS-Cov-2 spike protein antibodies were assessed before and after vaccination.

Results

Anti-SARS-CoV-2 antibodies were detected in 34% of the patients: 33.7% of kidney transplant patients, 47.7% of liver transplant patients, and 14.3% of thoracic transplant patients (P = 0.005). Independent predictive factors for humoral response after vaccination were male gender, a longer period between transplantation and vaccination, liver transplant recipients, a higher lymphocyte count at baseline, a higher estimated glomerular filtration rate and receiving the tacrolimus + everolimus ± steroids combination. Conversely, the nondevelopment of anti-SARS-CoV-2 antibodies after vaccination was associated with younger patients, thoracic organ recipients, induction therapy recipients, and tacrolimus + mycophenolic acid ± steroids recipients.

Conclusions

The immunosuppressive regimen is a modifiable predictive factor for humoral response to SARS-CoV-2 vaccine.

Coronavirus Disease 2019 (COVID-19) in Solid Organ Transplant Recipients: A Case-Control Study

Background

It is unclear whether solid organ transplant (SOT) patients have more severe coronavirus disease 2019 (COVID-19) and worse outcome than the general population.

Material/Methods

We conducted a case-control study on 32 SOT recipients and 84 non-SOT controls matched for age and sex admitted for confirmed COVID-19. The primary endpoint was in-hospital all-cause mortality rate. Secondary endpoints included severe acute respiratory distress syndrome (ARDS), use of high-flow oxygen therapy, and length of hospital stay.

Results

The median (IQR) Charlson comorbidity index (CCI) at admission was significantly higher in SOT recipients (6 (3–8) vs 3 (2–4); P<0.01). Fever was less frequent in SOT recipients (78% vs 94%, P=0.01). SOT recipients had a higher median SaO2/FiO2 at admission (452 [443–462] vs 443 [419–452], P<0.01) and reached the worst SaO2/FiO2 value later during hospitalization 15 (10–21) vs 11 (9–14) days, P=0.01). Both groups had a similar severe ARDS rate during hospitalization (33% vs 28%) (p=0.59). There were no significant differences during hospitalization in terms of highest level of respiratory support needed, or length of hospital stay: 8.5 (5.5–21) vs 11.5 (6.5–16.5) days; P=0.34) in SOT recipients when compared to controls. In-hospital all-cause mortality rates were significantly higher in SOT recipients (21.9% vs 4.7%, P<0.01; OR 1.08; 95% CI 0.10–10.98), but among patients who died, median CCI was similar between groups (8 [6–8] vs 7 [6–8]).

Conclusions

In our experience, hospitalized SOT recipients for COVID-19 had higher in-hospital mortality compared to non-SOT patients, probably due to the greater number of underlying comorbidities, and not directly related to chronic immunosuppression.

COVID-19 in lung transplant recipients: an overview of the Swedish national experience

Although it is known that solid organ transplant recipients fare worse after COVID-19 infection, data on the impact of COVID-19 on clinical outcomes and allograft function in lung transplant (LTx) recipients are limited and based mainly on reports with short follow-up. In this nationwide study, all LTx recipients with COVID-19 diagnosed from 1 February 2020 to 30 April 2021 were included. The patients were followed until 1 August 2021 or death. We analysed demographics, clinical features, therapeutic management and outcomes, including lung function. Forty-seven patients were identified: median age was 59 (10-78) years, 53.1% were male, and median follow-up was 194 (23-509) days. COVID-19 was asymptomatic or mild at presentation in 48.9%. Nine patients (19.1%) were vaccinated pre-COVID infection. Two patients (4.3%) died within 28 days of testing positive, and the overall survival rate was 85.1%. The patients with asymptomatic or mild symptoms had a higher median % expected forced expiratory volume during the first second than the patients with worse symptoms (P = 0.004). LTx recipients develop the entire spectrum of COVID-19, and in addition to previously acknowledged risk factors, lower pre-COVID lung function was associated with more severe disease presentation.

Prospective Clinical, Virologic, and Immunologic Assessment of COVID-19 in Transplant Recipients

BACKGROUND

Several studies have described the clinical features of COVID-19 in solid-organ transplant recipients. However, many have been retrospective or limited to more severe cases (hospitalized) and have not routinely included serial virological sampling (especially in outpatients) and immunologic assessment.

METHODS

Transplant patients diagnosed with COVID-19 based on a respiratory sample PCR were prospectively followed up to 90 d. Patients provided consent for convalescent serum samples and serial nasopharyngeal swabs for SARS-CoV-2 antibody (antinucleoprotein and anti-RBD) and viral load, respectively.

RESULTS

In the 161 SOT recipients diagnosed with COVID-19, the spectrum of disease ranged from asymptomatic infection (4.3%) to hospitalization (60.6%), supplemental oxygen requirement (43.1%), mechanical ventilation (22.7%), and death (15.6%). Increasing age (OR, 1.031; 95% CI, 1.001-1.062; P = 0.046) and ≥2 comorbid conditions (OR, 3.690; 95% CI, 1.418-9.615; P = 0.007) were associated with the need for supplemental oxygen. Allograft rejection was uncommon (3.7%) despite immunosuppression modification. Antibody response at ≥14 d postsymptoms onset was present in 90% (anti-RBD) and 76.7% (anti-NP) with waning of anti-NP titers and stability of anti-RBD over time. Median duration of nasopharyngeal positivity was 10.0 d (IQR, 5.5-18.0) and shedding beyond 30 d was observed in 6.7% of patients. The development of antibody did not have an impact on viral shedding.

CONCLUSIONS

This study demonstrates the spectrum of COVID-19 illness in transplant patients. Risk factors for severe disease are identified. The majority form antibody by 2 wk with differential stability over time. Prolonged viral shedding was observed in a minority of patients. Reduction of immunosuppression was a safe strategy.

Improving the Outcomes of Immunocompromised Patients With Coronavirus Disease 2019

Recent case studies have highlighted the fact that certain immunocompromised individuals are at risk for prolonged SARS-CoV-2 replication, intrahost viral evolution of multiply-mutated variants, and poor clinical outcomes. The immunologic determinants of this risk, the duration of infectiousness, and optimal treatment and prevention strategies in immunocompromised hosts are ill defined. Of additional concern is the widespread use of immunosuppressive medications to treat COVID-19, which may enhance and prolong viral replication in the context of immunodeficiency. We outline the rationale for 4 interrelated approaches to usher in an era of evidence-based medicine for optimal management of immunocompromised patients with COVID-19: multicenter pathogenesis and outcomes studies to relate the risk of severe disease to the type and degree of immunodeficiency, studies to evaluate immunologic responses to SARS-CoV-2 vaccines, studies to evaluate the efficacy of monoclonal antibodies for primary prophylaxis, and clinical trials of novel antiviral agents for the treatment of COVID-19.

mTOR-Inhibition and COVID-19 in Kidney Transplant Recipients: Focus on Pulmonary Fibrosis

Kidney transplant recipients are at high risk of developing severe COVID-19 due to the coexistence of several transplant-related comorbidities (e.g., cardiovascular disease, diabetes) and chronic immunosuppression. As a consequence, a large part of SARS-CoV-2 infected patients have been managed with a reduction of immunosuppression. The mTOR-I, together with antimetabolites, have been often discontinued in order to minimize the risk of pulmonary toxicity and to antagonize pharmacological interaction with antiviral/anti-inflammatory drugs. However, at our opinion, this therapeutic strategy, although justified in kidney transplant recipients with severe COVID-19, should be carefully evaluated in asymptomatic/paucisymptomatic patients in order to avoid the onset of acute allograft rejections, to potentially exploit the mTOR-I antiviral properties, to reduce proliferation of conventional T lymphocytes (which could mitigate the cytokine storm) and to preserve Treg growth/activity which could reduce the risk of progression to severe disease. In this review, we discuss the current literature regarding the therapeutic potential of mTOR-Is in kidney transplant recipients with COVID-19 with a focus on pulmonary fibrosis.

Liver Transplantation Services During the Time of COVID-19

The coronavirus disease 2019 (COVID-19) is associated with high morbidity and mortality, prompting overwhelmed hospital systems to reallocate resources to those stricken with the disease. In response, many liver transplantation programs unexpectedly came to an abrupt halt, significantly affecting the lives of living donors and recipients around the world. As the risk-benefit scale of liver transplantation has changed in the era of COVID-19, it is prudent to understand the impact of COVID-19 on those with underlying liver disease and those in need of a liver transplant. In this review, we discuss recommendations put forth by hepatology and transplant societies, summarize results from emerging studies, and propose strategies to appropriately risk stratify patients prior to transplantation.

COVID-19 and Effect on Liver Transplant

PURPOSE OF REVIEW

The Coronavirus disease-2019 (COVID-19) pandemic has significantly impacted all aspects of liver transplantation. We reviewed the literature regarding COVID-19 clinical outcomes, treatment, and vaccination of liver transplant candidates and recipients.

RECENT FINDINGS

Patients with chronic liver disease, especially with cirrhosis, have higher morbidity and mortality from COVID-19 than patients without liver disease. Increased mortality has not been consistently seen in liver transplant recipients, in whom severe disease is more strongly associated advanced age and medical comorbidities, rather than with transplant-specific factors. While several targeted COVID-19 therapies have reported hepatotoxicity, these therapies may be safe and effective in patients with liver disease and liver transplant recipients. Questions remain regarding whether SARS-CoV-2 can be transmitted via the donor liver and whether transplant is safe in patients and/or donors with recent or active COVID-19.

SUMMARY

COVID-19 has significantly affected the care of liver transplant candidates and recipients. Guidelines for the safe practice of liver transplantation are rapidly evolving, and current recommendations are discussed.