Objectives: There are limited clinical data on feasibility and safety of convalescent plasma therapy in kidney transplant recipients with severe COVID-19. The present study was conducted to explore the feasibility of convalescent plasma treatment in 10 kidney transplant recipients with severe COVID-19.

Materials and Methods: The prospective observational cohort study was conducted at the Institute of Kidney Disease and Research Centre, Ahmedabad, India. All patients were admitted to the intensive care unit and received antiviral therapy, glucocorticoids, and other supportive care. Two doses of 200 mL each of convalescent plasma with neutralization activity of >1:640 were transfused into patients 24 hours apart following the World Health Organization blood transfusion protocol. The endpoints were the improvement of clinical symptoms and laboratory parameters within 1 day and 7 days after convalescent plasma transfusion.

Results: The patients showed resolution of clinical symptoms, and there was a significant decrease in inflammatory markers (P < .05) within 7 days of convalescent plasma transfusion. Of the 10 patients, 9 patients had full recovery and 1 patient died.

Conclusions: Convalescent plasma therapy is highly safe and clinically feasible and reduces mortality in kidney transplant recipients with severe COVID-19. Larger clinical registries and randomized clinical trials should be conducted to further explore the clinical outcomes associated with convalescent plasma use in kidney transplant recipients with severe COVID-19.

Key words : Convalescent plasma, Immunosuppression, Inflammatory markers, Kidney transplantation, Severe acute respiratory syndrome

Introduction

The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emerged as a global pandemic.¹

As of January 28, 2020, India carries the second largest COVID-19 burden in the world, with 1.62% (n = 173 740) active COVID-19 cases undergoing treatment, 96.94% (n = 10 373 606) patients cured/discharged, and 1.44% (n = 153 847) patients who died.² Tragically, India has at this time the second highest COVID-19 caseload in the world, and COVID-19 is having serious impacts on the 850 million people with kidney-related ailments, including the 3.9 million on regular dialysis and also recipients of kidney transplant.³ The clinical data on COVID‐19 among kidney transplant recipients (KTRs) are still scarce and limited to reports from China, Spain, Italy, the United States, Germany, France, the United Kingdom, and other international registries. The current treatment of COVID‐19 has been limited to general supportive care with provision of critical care, as no approved therapies are yet available.⁴

Immune (ie, “convalescent”) plasma refers to plasma that is collected from individuals after resolution of infection and development of antibodies. There are numerous examples in which convalescent plasma (CP) has been used successfully as postexposure prophylaxis and/or treatment of infectious diseases, including in other outbreaks of coronaviruses (eg, severe acute respiratory syndrome 1, Middle East respiratory syndrome).⁵ Hence, CP transfusion has been the subject of increasing attention, especially in the wake of a large‐scale epidemic.⁶ It has recently been suggested by the US Food and Drug Administration that administration and study of investigational CP transfusion may provide a clinical effect for treatment of COVID‐19 during the COVID-19 public health emergency.⁷ Patients who have recovered from COVID-19 with a high neutralizing antibody titer may be a valuable donor source of CP. However, there is no documented evidence on clinical benefits and outcomes of CP in KTRs with COVID-19. Hence, we explored the feasibility of CP treatment in 10 KTRs with severe COVID-19.

Materials and Methods

We had conducted this prospective observational cohort study at the Institute of Kidney Disease and Research Centre, Ahmedabad, India. The study was approved by the ethics committee of the institution before the study began. We also abided by the Declaration of Helsinki and Declaration of Istanbul principles. Written informed consent was obtained from all recipients or their legal relatives.

Our Institute is one of the largest tertiary care centers of its kind in Gujarat, India, with around 400 total indoor beds for nephrology, urology, and transplantation. More than 6000 renal transplants, including with both living and deceased donors, have been conducted at our Institute, with around 390 renal transplants performed in 2019. During the peak of COVID-19, our institute was converted into a dedicated COVID-19 center, with around 200 beds assigned to COVID-19 patients.

Patients
Ten KTRs diagnosed with severe COVID-19 were recruited for this study All patients were diagnosed as having severe COVID-19 according to the WHO Interim Guidance8 and the Guideline of Diagnosis and Treatment of COVID-19 of National Health Commission of China (version 5.0),9 with confirmation by real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay. The enrollment criteria were one of conditions 2 to 4 plus condition 1: (1) age ≥18 years, (2) respiratory distress (respiratory rate of ≥30 breaths/min), (3) oxygen saturation level <93% in resting state, and (4) Pao2/fraction of inspired oxygen (Fio2) ≤300 mm Hg (1 mm Hg = 0.133 kPa). The exclusion criteria were as follows: (1) previous allergic history to plasma or ingredients (sodium citrate) and (2) patients with serious general conditions, such as severe organ dysfunction, who were not suitable for CP transfusion.

Donors
Requirement for plasma donors included patients who had recovered from symptoms (fever, cough, cold, etc) or were asymptomatic with anti-SARS-CoV-2 immunoglobulin G antibodies present. Symptomatic patient donors required complete resolution of symptoms at least 14 days before donation, preferably with 1 negative RT-PCR test for COVID-19 or complete resolution of symptoms for 28 days, with RT-PCR negative report not mandatory in this situation.10 Written informed consent was obtained from each donor.

Treatment
All patients were admitted to the intensive care unit and received antiviral therapy, glucocorticoids, and other supportive care. Two doses of 200 mL each of CP with neutralization activity of >1:640 was transfused into patients 24 hours apart in accordance with the World Health Organization (WHO) blood transfusion protocol.

Outcome measures and definitions
Endpoints were improvements of clinical symptoms and laboratory parameters within 1 day and 7 days after CP transfusion. Clinical symptom improvement was defined as normal temperature and impro­vement of Pao2/Fio2 after CP transfusion.

Statistical analyses
Quantitative continuous variables are given as medians and interquartile ranges (IQR) and were analyzed with the Mann-Whitney U test. Qualitative categorical variables are expressed as counts and percentages and were compared with the Fisher exact test or t test for paired samples. Statistical analysis was performed using the SPSS Statistical Package for Social Science version 17.0. P < .05 was considered statistically significant.

Results

Our study included 10 KTRs with severe COVID-19 (8 males and 2 females) who received CP transfusion. The characteristics of patients are summarized in Table 1. Median age of patients was 44.5 years (IQR, 26-56 y). Nine patients underwent living donor transplant, and 1 patient had deceased donor transplant. Five patients had hypertension, and 2 patients had type 2 diabetes mellitus as comorbid illness. Six patients had undergone kidney transplant within the previous 12 months. Most of our patients had received rabbit antithymocyte globulin as an induction agent at the time of transplant, with 1 patient receiving interleukin 2 blocker (Simulect, Novartis India Ltd). All patients at presentation were on maintenance triple immunosuppressive therapy that included steroid, calcineurin inhibitor (tacrolimus), and mycophenolate mofetil. The immuno­suppressive regimen was changed to double immunosuppressive agents by stopping myco­phenolate mofetil after diagnosis of COVID-19 by RT-PCR.

The most common symptoms at onset were shortness of breath (90%), cough (80%), and fever (80%). All patients required oxygen therapy at presentation, with 3 patients on nasal cannula, 6 patients on non-rebreather face mask, and 1 patient on invasive ventilation. All patients had ground-glass opacities on high-resolution computed tomo­graphy chest scans. The mean white blood cell count was 6.737 ± 2.97/mm3, and the baseline serum creatinine level was 1.738 ± 0.87 mg/dL. The median time from onset of symptoms to hospital admission and CP transfusion was 3 days (IQR, 2-5 days) and 5 days (IQR, 3-8 days), respectively. All patients received therapy with intravenous methyl­prednisolone (30 mg every 12 hours) and remdesivir (200 mg once a day for 10 days). The clinical and laboratory characteristics of patients are shown in Table 2.

Effects of CP transfusion
In 9 patients, all symptoms, especially fever, cough, and shortness of breath, disappeared or largely improved within 1 to 7 days of CP transfusion. Seven patients complained of fever before CP transfusion, and fever disappeared in all patients after CP transfusion. Prior to CP treatment, 3 patients required high-flow nasal cannula oxygenation, 6 required non-rebreather masks, and 1 patient was on mechanical ventilation. After treatment with CP, 2 patients were weaned from the non-rebreather masks to intermittent oxygenation, and 7 patients discon­tinued oxygen requirement. The Pao2/Fio2 ranged from 70 to 156 mm Hg before transfusion and increased within 7 days after transfusion (overall range, 284-416 mm Hg) (Table 3).

Improvement of laboratory criteria
Laboratory results were assessed for parameters associated with inflammation. The mean ± standard deviation value for highly sensitive C-reactive protein (hsCRP) decreased in our study from 133.36 ± 46.31 mg/L (IQR, 63.8-204 mg/L) at day 0 to 41.83 ± 37.44 mg/L (IQR, 19.9-145.8 mg/L) and 7 ± 3.02 mg/L (IQR, 2.1-9.6 mg/L) at days 1 and 7 after transfusion, respectively. A similar trend was observed in interleukin 6 (IL-6) levels, decreasing from 189.11 ± 83.84 pg/mL (IQR, 104-318.7 pg/mL) at day 0 to 60.75 ± 47.94 pg/mL (IQR, 17.91-165 pg/mL) and 12.63 ± 9.16 pg/mL (IQR:1.8-28.1 pg/mL) at days 1 and 7 after transfusion (Table 3). The declines in inflammatory markers, hsCRP (133.36 vs 7 mg/L; P < .05) and IL-6 (189.11 vs 12.63 pg/mL; P < .05), were found to be statistically significant at day 7 post-CP transfusion. There was no association found between the levels of D-dimer before and after CP transfusion.

Patients treated with plasma therapy had good clinical outcomes. The mean duration of patients becoming COVID-19 negative after CP transfusion was 7.4 ± 15 days; after CP transfusion, the mean length of hospital stay was 16.3 ± 7.2 days. Of 10 patients, 9 were discharged from the hospital, and only 1 patient died.

Discussion

We report the successful use of CP therapy in KTRs with severe COVID-19. Of 10 patients enrolled in our study, 9 patients had full recovery after CP transfusion, with mortality seen in 1 patient. In India, COVID-19-related mortality is 1.8% in the general population2 and 5% to 20% in hospitalized patients,¹¹ whereas KTRs have reportedly higher mortality of 4.8% to 33%.^12,13 In our study, we had a mortality of 10% among the 10 KTRs with severe COVID-19 after CP transfusion.

In the present study, overall clinical characteristics (symptoms, laboratory examinations, and high-resolution computed tomography chest scans) were similar to those of other nontransplanted adult patients with COVID‐19.¹⁴ It has been hypothesized that immunosuppressed patients may not be at increased risk of complications in the setting of coronavirus infections compared with the general population.¹⁵ However, in our setting, patients had severe clinical features, despite being on immuno­suppressive therapy. The rapid viral replication of SARS-CoV-2 triggers inflammatory responses that play critical roles in the progression of COVID-19 by inducing release of cytokines and chemokines.16 Inflammatory markers, such as hsCRP and IL-6, have been reported to be significantly increased in patients with severe COVID-19.¹⁷ In our study, all KTRs with severe COVID-19 had raised inflammatory markers at presentation; hence, despite being under chronic immunosuppression, KTRs showed an increase in inflammatory markers similar to those of nonim­munosuppressed COVID-19 patients.

Convalescent plasma therapy has a long history of use in the treatment of infectious diseases. Its use has been well-documented during the outbreak of many diseases at various periods, including Spanish influenza A (H1N1) infections in 1915 to 1917,¹⁸ severe acute respiratory syndrome in 2003,¹⁹

the pandemic 2009 influenza A (H1N1),²⁰ avian influenza A (H5N1),21 several hemorrhagic fevers such as Ebola,²² and other viral infections. In view of the above effective role of CP therapy, it was deployed in our study as a therapeutic agent for KTRs with severe COVID-19. The previous experiences of severe acute respiratory syndrome and severe influenza had recommended early use of CP therapy because the production of endogenous immunoglobulin M and G antibodies peaks at 2 and 4 weeks after infection, respectively.^18,19 In the present study, CP transfusion was done within 5 days (IQR, 3-8 days) from the onset of symptoms, and 90% of patients had improvements of clinical symptoms after transfusion, thus showing a role for early administration of CP in KTRs with severe COVID-19. In a study from Salazar and associates, early CP transfusion in COVID-19 patients reduced mortality.²³

In our study, patients had normalization of body temperature, increased Pao2/Fio2, and decreased inflammatory markers after CP transfusion. In the study from Shen and associates,24 which included 5 critically ill COVID‐19 patients, body temperature normalized within 3 days, the Sequential Organ Failure Assessment Score decreased, and Pao2/Fio2 increased after CP transfusion. Duan and colleagues25 also concluded that, after CP therapy, clinical symptoms improved significantly within 3 days, with reported decreases in the inflammatory marker C-reactive protein (55.98 vs 18.13 mg/L). In view of these findings, CP therapy showed effectiveness in resolution of clinical symptoms and amelioration of inflammatory markers after transfusion.

With regard to our finding of CP therapy being highly safe and clinically feasible and reducing mortality in KTR with severe COVID-19, Naeem and colleagues26 had similar conclusions, reporting successful recovery of 3 COVID-19 KTRs after CP therapy. These conclusions were also made by Rajendran and associates²⁷ in their systematic review on CP in the treatment of COVID-19.

There are some limitations to the present study. First, our study has a small sample size, and there were no controls. Second, all patients received antiviral therapy despite the uncertainty of the efficacy of drugs used. As a result, there is a possibility that these antiviral agents contributed to the recovery of patients or synergized with the therapeutic effects of CP. Despite these limitations, we report here the successful recovery from severe COVID‐19 in 9 KTRs who received CP therapy. Larger clinical registries and randomized clinical trials should be conducted to further explore the efficacy of CP in KTRs with severe COVID‐19.

Conclusions

As SARS‐CoV‐2 continues to spread worldwide, there is a compelling need to control the greatest global health crisis by COVID‐19 outbreak. Currently, there is no reliable therapeutic options for KTRs who have severe COVID‐19. Although a definitive conclusion cannot be drawn, CP therapy could be a feasible therapeutic option, having promising evidence of safety, improving clinical symptoms, and reducing mortality in KTRs with severe COVID‐19.

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