Assessment of Seroconversion to SARS-CoV-2 in a Cohort of Pediatric Kidney Transplant Recipients

Pediatric transplantation during the COVID-19 pandemic

Children infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seem to have a better prognosis than adults. Nevertheless, pediatric solid organ transplantation (SOT) has been significantly affected by the unprecedented coronavirus disease 2019 (COVID-19) pandemic during the pre-, peri-, and post-transplant period. Undoubtedly, immunosuppression constitutes a real challenge for transplant clinicians as increased immunosuppression may prolong disease recovery, while its decrease can contribute to more severe symptoms. To date, most pediatric SOT recipients infected by SARS-CoV-2 experience mild disease with only scarce reports of life-threatening complications. As a consequence, after an initial drop during the early phase of the pandemic, pediatric SOTs are now performed with the same frequency as during the pre-pandemic period. This review summarizes the currently available evidence regarding pediatric SOT during the COVID-19 pandemic.

Humoral and cellular immune response to severe acute respiratory syndrome coronavirus-2 vaccination in haemodialysis and kidney transplant patients

End-stage renal disease (ESRD) patients are amongst the vulnerable groups and thus prioritized in the Coronavirus disease-2019 vaccination programmes. However, this cohort was excluded from vaccine-trials and yet shares the same vaccination scheme with the general population. Here, we explore trends of immune response-proportions amongst ESRD patients on renal replacement therapy for up to 4 weeks post-vaccination completion with Pfizer/Moderna vaccines. From inception to 10 July 2021, we searched six online-databases for articles reporting humoral and cellular immune response proportions for up to 4 weeks post booster-vaccination. We pooled the responders' proportions by meta-analysis and conducted a meta-regression stratifying outcomes by significant confounders. Twenty-seven eligible studies reported 2789 ESRD patients. 1337, 1452 and 477 were on haemodialysis, received kidney transplantation, and healthy controls, respectively. Haemodialysis patients' proportions of humoral and cellular immune responses varied from 87.29% (80.77-93.81)-88.78% (86.76-90.80) and 62.86% (56.56, 69.17)-85.78% (78.99, 92.57), respectively, between first- and fourth-weeks. Kidney transplant patients' proportions of humoral and cellular immune responses ranged from 2.6% (0.06-13.48)-29.87% (27.68, 32.07) and 5.13% (0.63-17.3)-59.84% (54.57-65.10), respectively, between first- and fourth-weeks. All healthy controls maintained ≥93% proportions of both responses throughout the follow-up. Study design and country of study influenced the pooled response proportions. Conclusively, haemodialysis and kidney transplant patients have lower proportions of humoral and cellular immune responses than healthy controls. However, haemodialysis patients' response proportions improve, reaching near healthy-control levels by the fourth week. Kidney transplant patients' lower responses' proportions also improve but remain significantly lower than healthy controls throughout four-weeks. The "one-size-fits-all" vaccination scheme might be inadequate for kidney transplant patients.

High rate of clinically unrecognized SARS-CoV-2 infections in pediatric palliative care patients

Little is known about the frequency and clinical course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in pediatric patients with severe comorbidities. In this prospective cross-sectional trial, the seroprevalence of SARS-CoV-2-IgG in patients with life-limiting conditions being treated by a large specialized pediatric palliative home-care team was determined. In order to gain insight into the infection chain, close contacts of seropositive patients were also included in the study. We analyzed the sera of 39 patients and found a 25.6% seroprevalence for SARS-CoV-2. No SARS-CoV-2 infections were known prior to the study. No significant difference was found in the symptom load between seropositive and seronegative patients during the risk period for SARS-CoV-2 infections. Of the 20 close contacts tested, only one was seropositive for SARS-CoV-2.Conclusions: Our results indicate a substantially high prevalence of silent SARS-CoV-2 infections in pediatric palliative care patients. Surprisingly, no severe outcomes were seen in this fragile patient collective with severe comorbidities. The chain of infection and thus the reason for the high frequency of SARS-CoV-2 infections in pediatric palliative care patients remain unclear. What is Known: •Even though severe disease courses of COVID-19 have been reported in children, there are yet no established risk factors for SARS-CoV-2 in pediatric patients. What is New: •In this cross-sectional seroprevalence study of palliative pediatric patients with severe life-limiting conditions, a high rate of seropositive patients (25.6%) was found. •Surprisingly, all seropositive patients were previously unrecognized, despite the severe comorbidities of our collective.

SARS-CoV-2 and pediatric solid organ transplantation: Current knowns and unknowns

The COVID-19 pandemic has proven to be a challenge in regard to the clinical presentation, prevention, diagnosis, and management of SARS-CoV-2 infection among children who are candidates for and recipients of SOT. By providing scenarios and frequently asked questions encountered in routine clinical practice, this document provides expert opinion and summarizes the available data regarding the prevention, diagnosis, and management of SARS-CoV-2 infection among pediatric SOT candidates and recipients and highlights ongoing knowledge gaps requiring further study. Currently available data are still lacking in the pediatric SOT population, but data have emerged in both the adult SOT and general pediatric population regarding the approach to COVID-19. The document provides expert opinion regarding prevention, diagnosis, and management of SARS-CoV-2 infection among pediatric SOT candidates and recipients.

Detection of SARS-CoV-2 antibodies in pediatric kidney transplant patients

BACKGROUND

The seroprevalence of SARS-CoV-2 infection has been studied in immunocompetent children. However, data in the pediatric kidney transplant population (PKT) are lacking.

METHODS

Using two commercial immunoassays that measured IgG antibodies against SARS-CoV-2 spike protein and IgG against the nucleocapsid (N) protein, we screened 72 PKT recipients who attended the outpatient clinic for routine blood work. The majority of patients with positive serology underwent an additional serology test at least once during subsequent clinical follow-up. Patients were confirmed to have SARS-CoV-2 infection if they had two positive tests.

RESULTS

Eight patients out of the 72 screened (11.1%) had positive results for SARS-CoV-2 IgG antibodies in both serological tests. Of those who tested positive, 4 had positive SARS-CoV-2 PCR results before screening. All patients were asymptomatic or had a history of mild symptoms. All tested patients had persistently positive antibodies at a median follow-up time of 75 days (IQR, 44.5, 86.5 days). One patient had a positive PCR test at 75 days and a positive serology test at 120 days post infection.

CONCLUSION

The seroprevalence of SARS-CoV-2 was relatively high (11.1%) in our population. Although all patients were asymptomatic or mildly symptomatic, they mounted a strong humoral immune response that persisted for a few months despite being on triple immunosuppressants. These findings have positive implications regarding vaccination efficacy in this group.