Excess Mortality Among Solid Organ Transplant Recipients in the United States During the COVID-19 Pandemic

Longitudinal outcomes of COVID-19 in solid organ transplant recipients from 2020 to 2023

Data regarding coronavirus disease 2019 (COVID-19) outcomes in solid organ transplant recipients (SOTr) across severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) waves, including the impact of different measures, are lacking. This cohort study, conducted from March 2020 to May 2023 in Toronto, Canada, aimed to analyze COVID-19 outcomes in 1975 SOTr across various SARS-CoV-2 waves and assess the impact of preventive and treatment measures. The primary outcome was severe COVID-19, defined as requiring supplemental oxygen, with secondary outcomes including hospitalization, length of stay, intensive care unit (ICU) admission, and 30-day and 1-year all-cause mortality. SARS-CoV-2 waves were categorized as Wildtype/Alpha/Delta (318 cases, 16.1%), Omicron BA.1 (268, 26.2%), Omicron BA.2 (268, 13.6%), Omicron BA.5 (561, 28.4%), Omicron BQ.1.1 (188, 9.5%), and Omicron XBB.1.5 (123, 6.2%). Severe COVID-19 rate was highest during the Wildtype/Alpha/Delta wave (44.6%), and lower in Omicron waves (5.7%-16.1%). Lung transplantation was associated with severe COVID-19 (OR: 4.62, 95% CI: 2.71-7.89), along with rituximab treatment (OR: 4.24, 95% CI: 1.04-17.3), long-term corticosteroid use (OR: 3.11, 95% CI: 1.46-6.62), older age (OR: 1.51, 95% CI: 1.30-1.76), chronic lung disease (OR: 2.11, 95% CI: 1.36-3.30), chronic kidney disease (OR: 2.18, 95% CI: 1.17-4.07), and diabetes (OR: 1.97, 95% CI: 1.37-2.83). Early treatment and ≥3 vaccine doses were associated with reduced severity (OR: 0.29, 95% CI: 0.19-0.46, and 0.35, 95% CI: 0.21-0.60, respectively). Tixagevimab/cilgavimab and bivalent boosters did not show a significant impact. The study concludes that COVID-19 severity decreased across different variants in SOTr. Lung transplantation was associated with worse outcomes and may benefit more from preventive and early therapeutic interventions.

Comparison of COVID-19 Hospitalization and Death Between Solid Organ Transplant Recipients and the General Population in Canada, 2020-2022

Background

Solid organ transplant recipients have a high risk of severe outcomes from SARS-CoV-2 infection. A comprehensive understanding of the impact of the COVID-19 pandemic across multiple waves in the solid organ transplant population and how this compares to the general population is limited. We conducted a population-based cohort study using linked administrative healthcare databases from Ontario, Canada to answer this question.

Methods

We included 15 306 solid organ transplant recipients and 12 160 904 individuals from the general population. Our primary outcome was the rate (per 100 person-years) of severe COVID-19 (ie, hospitalization or death with a positive SARS-CoV-2 test) occurring between January 25, 2020, and November 30, 2022.

Results

Compared with the general population, solid organ transplant recipients had almost a 6 times higher rate of severe COVID-19 (20.39 versus 3.44 per 100 person-years), with almost 5.5 times as high a rate of death alone (4.19 versus 0.77 per 100 person-years). Transplant recipients with severe COVID-19 were substantially younger (60.1 versus 66.5 y) and had more comorbidities. The rate of severe COVID-19 declined over time in the solid organ transplant population, with an incidence rate of 41.25 per 100 person-years in the first wave (January 25, 2020, to August 31, 2020) and 18.41 in the seventh wave (June 19, 2022, to November 30, 2022, Omicron era).

Conclusions

Solid organ transplant recipients remain at high risk of severe outcomes when they are infected with SARS-CoV-2. Resources and strategies to mitigate the impact of SARS-CoV-2 exposure are needed in this vulnerable patient population.

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.

COVID-19 Reinfection Has Better Outcomes Than the First Infection in Solid Organ Transplant Recipients

BACKGROUND

Solid organ transplant recipients face an increased risk of severe coronavirus disease 2019 (COVID-19) and are vulnerable to repeat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. In nonimmunocompromised individuals, SARS-CoV-2 reinfections are milder likely because of cross-protective immunity. We sought to determine whether SARS-CoV-2 reinfection exhibits milder manifestations than primary infection in transplant recipients.

METHODS

Using a large, prospective cohort of adult transplant patients with COVID-19, we identified patients with SARS-CoV-2 reinfections. We performed a 1:1 nearest neighbor propensity score matching to control potential confounders, including the COVID-19 variant. We compared outcomes including oxygen requirement, hospitalization, and intensive care unit admission within 30 d after diagnosis between patients with reinfection and those with the first episode of COVID-19.

RESULTS

Between 2020 and 2023, 103 reinfections were identified in a cohort of 1869 transplant recipients infected with SARS-CoV-2 (incidence of 2.7% per year). These included 50 kidney (48.5%), 27 lung (26.2%), 7 heart (6.8%), 6 liver (5.8%), and 13 multiorgan (12.6%) transplants. The median age was 54.5 y (interquartile range [IQR], 40.5-65.5) and the median time from transplant to first infection was 6.6 y (IQR, 2.8-11.2). The time between the primary COVID-19 and reinfection was 326 d (IQR, 226-434). Three doses or more of SARS-CoV-2 vaccine are received by 87.4% of patients. After propensity score matching, reinfections were associated with significantly lower hospitalization (5.8% versus 19.4%; risk ratio, 0.3; 95% CI, 0.12-0.71) and oxygen requirement (3.9% versus 13.6%; risk ratio, 0.29; 95% CI, 0.10-0.84). In a within-patient analysis only in the reinfection group, the second infection was milder than the first (3.9% required oxygen versus 19.4%, P  < 0.0001), and severe first COVID-19 was the only predictor of severe reinfection.

CONCLUSIONS

Transplant recipients with COVID-19 reinfection present better outcomes than those with the first infection, providing clinical evidence for the development of cross-protective immunity.

Excess mortality among kidney transplant recipients: Impact of COVID-19-related deaths during the pandemic

BACKGROUND

Because COVID-19 has been associated with high lethality rates among kidney transplant recipients (KTR), but also with a severe disruption and delays in overall healthcare, this study aims to evaluate the excess mortality in the pandemic era among KTR in a high-volume Brazilian transplant center.

METHODS

This study used data from a single center that provides follow-up on all its transplant recipients. The population of interest included all the patients who were transplanted between August 31, 1983 and December 31, 2022 and who were live from January 1, 2014. Using the "AutoRegressive Integrated Moving Average" forecasting algorithm, the expected mortality for the pandemic era (2020-2022) was modeled from the pre-pandemic era (2014-2019).

RESULTS

There were 12 077 KTRs at risk of dying in the entire observation period. In the pre-pandemic era, there were 21 deaths per 1000 patients at risk. In the pandemic era, there were 1429 observed deaths (rate of 47 deaths per 1000 patients at risk) versus the expected 587 deaths, resulting in an absolute number of 842 excess deaths, or an observed-to-expected ratio of 2.4, or an absolute rate of 26 deaths in excess per 1000 patients at risk. The excess deaths exhibited a temporal pattern mirroring that of the surges in new cases and lethality rates of COVID-19. COVID-19-related deaths drove 94% of excess mortality in the pandemic era.

CONCLUSION

In this large cohort of KTR under centralized follow-up, more than twofold excess mortality was primarily driven by COVID-19-related deaths, highlighting the vulnerability of this population to the most severe presentation of SARS-CoV-2 infection.

COVID-19 Outcomes in Lung Transplant Recipients Following Pre-Exposure Prophylaxis With Tixagevimab-Cilgavimab During the Omicron BA.5 Surge: A Single Center Analysis

Lung transplant (LTx) recipients are at high risk for COVID-19 related morbidity and mortality. Data regarding pre-exposure prophylaxis (PrEP) with tixagevimab-cilgavimab in this population are scarce. We therefore evaluated COVID-19 breakthrough infections and COVID-19 related complications after PrEP in a retrospective single-center study, including 264 LTx recipients who received PrEP between June 2022 and December 2022, when Omicron BA.5 was the dominant circulating SARS-CoV-2 variant. PrEP was indicated for fully vaccinated patients with poor seroconversion (anti-S <260 BAU/mL). COVID-19 breakthrough infection after PrEP occurred in 11.0% within the first 3 months, increasing to 17.4% within 6 months. Hospitalization rate rose from 27.6% to 52.9% (p = 0.046), while ICU admissions and COVID-19 mortality remained low, respectively occurring in 6.5% and 4.3% of patients with breakthrough infection within 6 months. COVID-19 breakthrough infection and associated hospitalization remained an important problem during the Omicron BA.5 surge in fully vaccinated LTx recipients with deficient seroconversion, despite PrEP with tixagevimab-cilgavimab. However, ICU admissions and COVID-19 mortality were low. Waning of neutralizing effects of PrEP and changing circulating SARS-CoV-2 variants may explain increases in COVID-19 infections and hospitalizations over time after PrEP, highlighting the need for novel, long-term effective PrEP strategies in these high-risk patients.

Tixagevimab-Cilgavimab Decreases the Rate of SARS-CoV-2 Infection Among Solid Organ Transplant Recipients

BACKGROUND

SARS-CoV-2 infection in solid organ transplant (SOT) recipients is associated with high morbidity and mortality. Tixagevimab/cilgavimab monoclonal antibodies were previously authorized for pre-exposure prophylaxis for immunocompromised individuals. We aimed to determine if tixagevimab/cilgavimab could prevent breakthrough SARS-CoV-2 infection in SOT recipients.

MATERIAL AND METHODS

We conducted a prospective single-center study of SOT recipients who received tixagevimab/cilgavimab compared with those who did not. Demographics, type of transplant, immunosuppression regimen, COVID-19 vaccination status, and tixagevimab/cilgavimab administration data were collected. Participants were interviewed for 6 months or until they tested positive for SARS-CoV-2, whichever came first. Kaplan-Meier SARS-CoV-2-free survival curves were created based on the tixagevimab/cilgavimab administration date and SARS-CoV-2 infection. The log-rank test was used for comparison. Univariate and multivariate Cox regression models were constructed.

RESULTS

The study cohort included 323 patients. Two hundred forty-eight received tixagevimab/cilgavimab, and 75 did not (control). COVID-19 vaccination rate was higher among tixagevimab/cilgavimab recipients than nontixagevimab/cilgavimab recipients (99.6% vs 92.0%; P < .001). Twenty-six patients in the tixagevimab/cilgavimab group (10.5%) and 23 in the control group (30.7%) tested positive for SARS-CoV-2 infection (P < .001). In a multivariate analysis, receipt of tixagevimab/cilgavimab and duration from transplant were both associated with reduced risk of SARS-CoV-2 infection (hazard ratio 0.431; 95% CI 0.224-0.828 and hazard ratio 0.917; 95% CI 0.861-0.978, respectively).

CONCLUSION

During the study period, SOT recipients who received tixagevimab/cilgavimab had a significantly lower rate of SARS-CoV-2 infection. There were no differences in symptom frequency, illness severity, hospitalization rate, or treatment of SARS-CoV-2 infection.

COVID-19 in hospitalized solid organ transplant recipients in a nationwide registry study

OBJECTIVES

Underlying immunodeficiency has been associated with worse clinical presentation and increased mortality in patients with COVID-19. We evaluated the mortality of solid organ transplant (SOT) recipients (SOTR) hospitalized in Spain due to COVID-19.

METHODS

Nationwide, retrospective, observational analysis of all adults hospitalized because of COVID-19 in Spain during 2020. Stratification was made according to SOT status. The National Registry of Hospital Discharges was used, using the International Classification of Diseases, 10th revision coding list.

RESULTS

Of the 117,694 adults hospitalized during this period, 491 were SOTR: kidney 390 (79.4%), liver 59 (12%), lung 27 (5.5%), and heart 19 (3.9%). Overall, the mortality of SOTR was 13.8%. After adjustment for baseline characteristics, SOTR was not associated with higher mortality risk (odds ratio [OR] = 0.79, 95% confidence interval [CI] 0.60-1.03). However, lung transplantation was an independent factor related to mortality (OR = 3.26, 95% CI 1.33-7.43), while kidney, liver, and heart transplantation were not. Being a lung transplant recipient was the strongest prognostic factor in SOT patients (OR = 5.12, 95% CI 1.88-13.98).

CONCLUSION

This nationwide study supports that the COVID-19 mortality rate in SOTR in Spain during 2020 did not differ from the general population, except for lung transplant recipients, who presented worse outcomes. Efforts should be focused on the optimal management of lung transplant recipients with COVID-19.

Humoral and cellular responses to repeated COVID-19 exposure in multiple sclerosis patients receiving B-cell depleting therapies: a single-center, one-year, prospective study

Multiple sclerosis patients treated with anti-CD20 therapy (aCD20-MS) are considered especially vulnerable to complications from SARS-CoV-2 infection due to severe B-cell depletion with limited viral antigen-specific immunoglobulin production. Therefore, multiple vaccine doses as part of the primary vaccination series and booster updates have been recommended for this group of immunocompromised individuals. Even though much less studied than antibody-mediated humoral responses, T-cell responses play an important role against CoV-2 infection and are induced efficiently in vaccinated aCD20-MS patients. For individuals with such decoupled adaptive immunity, an understanding of the contribution of T-cell mediated immunity is essential to better assess protection against CoV-2 infection. Here, we present results from a prospective, single-center study for the assessment of humoral and cellular immune responses induced in aCD20-MS patients (203 donors/350 samples) compared to a healthy control group (43/146) after initial exposure to CoV-2 spike antigen and subsequent re-challenges. Low rates of seroconversion and RBD-hACE2 blocking activity were observed in aCD20-MS patients, even after multiple exposures (responders after 1st exposure = 17.5%; 2nd exposure = 29.3%). Regarding cellular immunity, an increase in the number of spike-specific monofunctional IFNγ+-, IL-2+-, and polyfunctional IFNγ+/IL-2+-secreting T-cells after 2nd exposure was found most noticeably in healthy controls. Nevertheless, a persistently higher T-cell response was detected in aCD20-MS patients compared to control individuals before and after re-exposure (mean fold increase in spike-specific IFNγ+-, IL-2+-, and IFNγ+/IL-2+-T cells before re-exposure = 3.9X, 3.6X, 3.5X/P< 0.001; after = 3.2X, 1.4X, 2.2X/P = 0.002, P = 0.05, P = 0.004). Moreover, cellular responses against sublineage BA.2 of the currently circulating omicron variant were maintained, to a similar degree, in both groups (15-30% T-cell response drop compared to ancestral). Overall, these results highlight the potential for a severely impaired humoral response in aCD20-MS patients even after multiple exposures, while still generating a strong T-cell response. Evaluating both humoral and cellular responses in vaccinated or infected MS patients on B-cell depletion therapy is essential to better assess individual correlations of immune protection and has implications for the design of future vaccines and healthcare strategies.

Predominantly defective CD8+ T cell immunity to SARS-CoV-2 mRNA vaccination in lung transplant recipients

BACKGROUND

Although mRNA vaccines have overall efficacy preventing morbidity/mortality from SARS-CoV-2 infection, immunocompromised persons remain at risk. Antibodies mostly prevent early symptomatic infection, but cellular immunity, particularly the virus-specific CD8+ T cell response, is protective against disease. Defects in T cell responses to vaccination have not been well characterized in immunocompromised hosts; persons with lung transplantation are particularly vulnerable to vaccine failure with severe illness.

METHODS

Comparison groups included persons with lung transplantation and no history of COVID-19 (21 and 19 persons after initial mRNA vaccination and a third booster vaccination respectively), 8 lung transplantation participants recovered from COVID-19, and 22 non-immunocompromised healthy control individuals after initial mRNA vaccination (without history of COVID-19). Anti-spike T cell responses were assayed by stimulating peripheral blood mononuclear cells (PBMCs) with pooled small overlapping peptides spanning the SARS-CoV-2 spike protein, followed by intracellular cytokine staining (ICS) and flow cytometry for release of cytokines in response to stimulation, including negative controls (no peptide stimulation) and positive controls (phorbol myristate acetate [PMA] and ionomycin stimulation). To evaluate for low frequency memory responses, PBMCs were cultured in the presence of the mRNA-1273 vaccine for 14 days before this evaluation.

RESULTS

Ionophore stimulation of PBMCs revealed a less inflammatory milieu in terms of interleukin (IL)-2, IL-4, and IL-10 profiling in lung transplantation individuals, reflecting the effect of immunosuppressive treatments. Similar to what we previously reported in healthy vaccinees, spike-specific responses in lung transplantation recipients were undetectable (< 0.01%) when tested 2 weeks after vaccination or later, but were detectable after in vitro culture of PBMCs with mRNA-1273 vaccine to enrich memory T cell responses. This was also seen in COVID-19-recovered lung transplantation recipients. Comparison of their enriched memory responses to controls revealed relatively similar CD4+ T cell memory, but markedly reduced CD8+ T cell memory both after primary vaccination or a booster dose. These responses were not correlated to age or time after transplantation. The vaccine-induced CD4+ and CD8+ responses correlated well in the healthy control group, but poorly in the transplantation groups.

CONCLUSIONS

These results reveal a specific defect in CD8+ T cells, which have key roles both in transplanted organ rejection but also antiviral effector responses. Overcoming this defect will require strategies to enhance vaccine immunogenicity in immunocompromised persons.

Abdominal Organ Transplantation: Noteworthy Literature in 2022

This review highlights noteworthy literature published in 2022 pertinent to anesthesiologists and critical care physicians caring for patients undergoing abdominal organ transplantation. We begin by exploring the impacts that the COVID-19 pandemic has had across the field of abdominal organ transplantation, including the successful use of grafts procured from COVID-19-infected donors. In pancreatic transplantation, we highlight several studies on dexmedetomidine and ischemia-reperfusion injury, equity in transplantation, and medical management, as well as studies comparing pancreatic transplantation to islet cell transplantation. In our section on intestinal transplantation, we explore donor selection. Kidney transplantation topics include cardiovascular risk management, obesity, and intraoperative management, including fluid resuscitation, dexmedetomidine, and sugammadex. The liver transplantation section focuses on clinical trials, systematic reviews, and meta-analyses published in 2022 and covers a wide range of topics, including machine perfusion, cardiovascular issues, renal issues, and coagulation/transfusion.

Kidney health for all: preparedness for the unexpected in supporting the vulnerable

As the rate of natural disasters and other devastating events caused by human activities increases, the burden on the health and well-being of those affected by kidney disease has been immeasurable. Health system preparedness, which involves creating a resilient system that is able to deal with the health needs of the entire community during times of unexpected disruptions to usual care, has become globally important. In the wake of the COVID-19 pandemic, there is a heightened awareness of the amplification of negative effects on the renal community. Paradoxically, the complex medical needs of those who have kidney diseases are not met by systems handling crises, often compounded by an acute increase in burden via new patients as a result of the crisis itself. Disruptions in kidney care as a result of unexpected events are becoming more prevalent and likely to increase in the years to come. It is therefore only appropriate that the theme for this year's World Kidney Day will focus on Kidney Health for All: preparedness for the unexpected in supporting the vulnerable.