Incidence of Hospitalization for Vaccine-Preventable Infections in Children Following Solid Organ Transplant and Associated Morbidity, Mortality, and Costs

Varicella-Zoster Virus Pretransplant Vaccination and Posttransplant Infections Among Pediatric Solid Organ Recipients in the Two-Dose Varicella Era: A Single-Center, Multi-Organ Retrospective Study

BACKGROUND

Varicella-zoster virus (VZV) pretransplant immunization rates, exposures, and posttransplant disease are poorly characterized among pediatric solid organ transplant (SOT) recipients in the two-dose varicella vaccine era.

METHODS

A retrospective analysis of the electronic health records among children <18 years old who received SOT from January 1, 2011 through December 31, 2021, was performed at a single center to assess for missed pretransplant varicella vaccination opportunities, characterize VZV exposures, and describe posttransplant disease.

RESULTS

Among 525 children, 444 were ≥6 months old (m.o.) at SOT with a documented VZV vaccine status. Eighty-five (19%) did not receive VZV Dose One; 30 out of 85 (35%) could have been immunized. Infants 6-11 m.o. accounted for 14 out of 30 (47%) missed opportunities. Among children ≥12 m.o. with documented Dose Two status (n = 383), 72 had missed vaccination opportunities; 57 out of 72 (79%) were children 1-4 years old. Most children had unclassifiable pre-SOT serostatus as varicella serology was either not obtained/documented (n = 171) or the possibility of passive antibodies was not excluded (n = 137). Of those with classified serology (n = 188), 69 were seroimmune. Forty-seven of 525 (9%) children had recorded VZV exposures; two developed varicella-neither had documented pre-SOT seroimmunity nor had received post-exposure prophylaxis. Nine additional children had medically attended disease: four primary varicella and five zoster. Of the 11 cases, 10 had cutaneous lesions without invasive disease; one had multi-dermatomal zoster with transaminitis. Seven (64%) received treatment exclusively outpatient.

CONCLUSIONS

VZV exposure and disease still occur. Optimizing immunization among eligible candidates and ensuring patients have a defined VZV serostatus pretransplantation remain goals of care.

Pre-Transplantation Strategies for Infectious Disease Mitigation and Prevention

Pediatric Infectious Disease (ID) clinicians play a critical role in helping prevent and mitigate infectious risks in children peri- and post-transplantation. Prevention starts during the pre-transplant evaluation and persists throughout the solid organ transplant and hematopoietic cell transplant continuum. The pre-transplant evaluation is an opportunity to screen for latent infections, plan preventative strategies, optimize immunizations, and discuss risk mitigation practices. An ideal pre-transplant evaluation establishes a relationship with the family that further promotes post-transplant infectious risk reduction. This manuscript builds on shared pediatric ID prevention strategies, introduces updated ID testing recommendations for transplant donors/candidates, highlights emerging data, and identifies ongoing knowledge gaps that are potential areas of research.

Diminished measles immunity after paediatric liver transplantation-A retrospective, single-centre, cross-sectional analysis

Liver transplantation in childhood has an excellent long-term outcome, but is associated with a long-term risk of infection. Measles is a vaccine-preventable infection, with case series describing severe courses with graft rejection, mechanical ventilation and even death in liver transplant recipients. Since about 30% of liver transplanted children receive liver transplants in their first year of life, not all have reached the recommended age for live vaccinations. On the contrary, live vaccines are contraindicated after transplantation. In addition, vaccination response is poorer in individuals with liver disease compared to healthy children. This retrospective, single-centre, cross-sectional study examines measles immunity in paediatric liver transplant recipients before and after transplantation. Vaccination records of 239 patients, followed up at Hannover Medical School between January 2021 and December 2022 were analysed. Twenty eight children were excluded due to stem cell transplantation, regular immunoglobulin substitution or measles vaccination after transplantation. More than 55% of all 211 children analysed and 75% of all those vaccinated at least once are measles seropositive after transplantation-48% after one and 84% after two vaccinations-which is less than in healthy individuals. Interestingly, 26% of unvaccinated children also showed measles antibodies and about 5-15% of vaccinated patients who were seronegative at the time of transplantation were seropositive afterwards, both possibly through infection. In multivariable Cox proportional hazards regression, the number of vaccinations (HR 4.30 [95% CI 2.09-8.83], p<0.001), seropositivity before transplantation (HR 2.38 [95% CI 1.07-5.30], p = 0.034) and higher age at time of first vaccination (HR 11.5 [95% CI 6.92-19.1], p<0.001) are independently associated with measles immunity after transplantation. In contrast, older age at testing is inversely associated (HR 0.09 [95% CI 0.06-0.15], p<0.001), indicating a loss of immunity. Vaccination in the first year of life does not pose a risk of non-immunity. The underlying liver disease influences the level of measles titres of twice-vaccinated patients; those with acute liver failure being the lowest compared to children with metabolic disease. In summary, vaccine response is poorer in children with liver disease. Liver transplant candidates should be vaccinated before transplantation even if this is earlier in the first year of life. Checking measles IgG and re-vaccinating seronegative patients may help to achieve immunity after transplantation.

Live-attenuated vaccination for measles, mumps, and rubella in pediatric liver transplantation

BACKGROUND

Infections are a serious short- and long-term problem after pediatric organ transplantation. In immunocompromised patients, they can lead to transplant rejection or a severe course with a sometimes fatal outcome. Vaccination is an appropriate means of reducing morbidity and mortality caused by vaccine-preventable diseases. Unfortunately, due to the disease or its course, it is not always possible to establish adequate vaccine protection against live-attenuated viral vaccines (LAVVs) prior to transplantation. LAVVs such as measles, mumps, and rubella (MMR) are still contraindicated in solid organ transplant recipients receiving immunosuppressive therapy (IST), thus creating a dilemma.

AIM

This review discusses whether, when, and how live-attenuated MMR vaccines can be administered effectively and safely to pediatric liver transplant recipients based on the available data.

MATERIAL AND METHODS

We searched PubMed for literature on live-attenuated MMR vaccination in pediatric liver transplantation (LT).

RESULTS

Nine prospective observational studies and three retrospective case series were identified in which at least 833 doses of measles vaccine were administered to 716 liver transplant children receiving IST. In these selected patients, MMR vaccination was well tolerated and no serious adverse reactions to the vaccine were observed. In addition, an immune response to the vaccine was demonstrated in patients receiving IST.

CONCLUSION

Due to inadequate vaccine protection in this high-risk group, maximum efforts must be made to ensure full immunization. MMR vaccination could also be considered for unprotected patients after LT receiving IST following an individual risk assessment, as severe harm from live vaccines after liver transplantation has been reported only very rarely. To this end, it is important to establish standardized and simple criteria for the selection of suitable patients and the administration of the MMR vaccine to ensure safe use.

Adherence to recommended vaccination policies for pre- and post-solid organ transplantation patients: A national questionnaire survey in Japan

BACKGROUND

Pre-transplant vaccination is recommended for patients undergoing solid organ transplantation (SOT). While appropriate vaccination protocols are implemented at some facilities, transplantation is sometimes performed with inadequate preoperative vaccine management. Vaccination rates vary across facilities, but those of SOT centers in Japan have never been investigated. This study aimed to conduct a nationwide questionnaire survey to assess pre- and post-transplant vaccination policies among SOT facilities in Japan.

METHODS

The survey was conducted from September to November 2022. All registered (n = 221) solid organ (namely, the lungs, liver, kidneys, pancreas, heart, and small intestine) transplant facilities were asked to complete a web-based survey.

RESULTS

The survey response rate was 70.2 %. Live and inactivated vaccines were recommended at 64.9 % and 68.9 % of the responding facilities, respectively. The following vaccines were incorporated into the vaccination protocols of facilities: pneumococcal vaccine, 31.7 % (13-valent pneumococcal conjugate vaccine) and 65.4 % (23-valent pneumococcal polysaccharide vaccine); hepatitis B virus vaccine, 67.3 %; severe acute respiratory syndrome coronavirus 2 vaccine, 73.1 %; influenza vaccine, 73.1 %; and zoster vaccines, 23.1 %. The reasons for unresponsiveness to vaccinations included inadequate time before transplantation (60.3 %), cost burden (41.1 %), high number of vaccinations (21.9 %), no recognition of the need for vaccination (17.9 %), and the requirement to explain the need for vaccination (15.2 %).

CONCLUSIONS

Our study revealed gaps in vaccination practices across nationwide facilities in Japan. The findings indicate the importance of promoting scheduled efficiency and encouraging the national health system to reduce vaccine costs with the support of public subsidies.

Parent and healthcare provider views of live varicella vaccination of pediatric solid organ transplant recipients

BACKGROUND

Live attenuated varicella vaccine (LAVV) has historically been contraindicated in children who are immunocompromised due to solid organ transplant (SOT) because of safety concerns. Recently, clinical guidelines were developed that support post-transplant varicella vaccination in selected SOT recipients based on emerging evidence of LAVV safety. This qualitative study sought to explore barriers and facilitators to implementing the new guidelines, as well as acceptability of LAVV among healthcare providers (HCPs) and parents.

METHODS

HCPs and parents of transplant recipients were recruited from four sites using purposive sampling. Data from semi-structured interviews were analyzed using an Interpretive Description approach that incorporated data from the interviews, academic knowledge and clinical experience, and drew from Grounded Theory and Thematic Analysis. The theoretical framework used was Adaptive Leadership.

RESULTS

Thirty-four participants (16 HCPs and 18 parents) were included in the analysis. Parents developed skills in adaptive leadership that included strategies to protect their child against infectious diseases. Foundational information that live vaccines were absolutely contraindicated post-transplant "stuck" with parents and led them to develop strategies other than vaccination to keep their child safe. Some parents struggled to understand that information previously presented as a certainty (contraindication of LAVV) could change. Their approach to adaptive leadership informed their appraisal of the new vaccination guidelines and willingness to accept vaccination.

CONCLUSIONS

HCPs should adopt a family-centered approach to communicating changing guidelines that considers parents' approach to adaptive leadership and discusses the changing nature of medical evidence. Trust between HCPs and parents can facilitate these conversations.

Approach to vaccinating the pediatric solid organ transplant candidate and recipient

Solid organ transplantation (SOT) candidates and recipients are at increased risk for morbidity and mortality from vaccine-preventable infections. Children are at particular risk given that they may not have completed their primary immunization series at time of transplant or have acquired natural immunity to pathogens from community exposures. Multiple society guidelines exist for vaccination of SOT candidate and recipients, although challenges remain given limited safety and efficacy data available for pediatric SOT recipients, particularly for live-vaccines. After transplant, individual patient nuances regarding exposure risks and net state of immunosuppression will impact timing of immunizations. The purpose of this review is to provide readers with a concise, practical, expert-opinion on the approach to vaccinating the SOT candidate and recipient and to supplement existing guidelines. In addition, pediatric-specific knowledge gaps in the field and future research priorities will be highlighted.

Safety and immunogenicity of the live-attenuated varicella vaccine in pediatric solid organ transplant recipients: A systematic review and meta-analysis

This study aimed to synthesize the available evidence on the immunogenicity, safety, and effectiveness of live-attenuated varicella vaccine in solid organ transplant recipients. Medline and EMBASE were searched using predefined search terms to identify relevant studies. The included articles reported varicella vaccine administration in the posttransplant period in children and adults. A pooled proportion of transplant recipients who seroconverted and who developed vaccine-strain varicella and varicella disease was generated. Eighteen articles (14 observational studies and 4 case reports) were included, reporting on 711 transplant recipients who received the varicella vaccine. The pooled proportion was 88.2% (95% confidence interval 78.0%-96.0%, 13 studies) for vaccinees who seroconverted, 0% (0%-1.2%, 13 studies) for vaccine-strain varicella, and 0.8% (0%-4.9%, 9 studies) for varicella disease. Most studies followed clinical guidelines for administering live-attenuated vaccines, with criteria that could include being at least 1 year posttransplant, 2 months postrejection episode, and on low-dose immunosuppressive medications. Varicella vaccination in transplant recipients was overall safe in the included studies, with few cases of vaccine-strain-induced varicella or vaccine failure, and although it was immunogenic, the proportion of recipients who seroconverted was lower than that seen in the general population. Our data support varicella vaccination in select pediatric solid organ transplant recipients.

Immunological Nuances and Complications of Pediatric Organ Transplant: A Narrative Review

Organ transplantation is considered an exaggerated immune state in which the body reacts in an elaborate cascade of reactions against the lifesaving graft transplanted. Unrepairable organ damage is the main indication for a pediatric patient to undergo a transplant. The host and the donor must fulfill the criteria for a successful transplant to have as few side effects as possible. There has been much-needed research in the domain of surgery of organ transplantation, thereby extending into the pediatric age group. This article elaborates on the post-transplant management, the immuno-biochemistry aspect, and its post-surgery treatment. The post-surgery period requires great emphasis as morbidity and mortality are highest. There is much to understand about managing transplant patients to avoid complications such as infections, hypertension, or side effects of immunosuppressive drugs. The treating clinician faces the challenges of managing the dose and frequency of immuno-suppressive medicines to prevent complications in the patients. If the dose is inadequate, there are chances of graft rejection. If the immuno-suppression is prolonged, there may be chances of infections in the patient. This article aims to summarize the mechanism of graft rejection and put forth the need for further research about creating a universal protocol for managing a patient's immune system post-transplant. The authors hope this protocol will help the clinician better understand the patient's current state and help in appropriately using immuno-suppressive drugs. It calls upon the need for a reliable and easily repeatable battery of investigations that will help solve this dilemma.

Single-Center Experience in Vaccination of Children in Special Risk Groups: A Multidisciplinary Institutional Consensus Protocol

OBJECTIVE

Despite marked improvements in the accessibility of childhood vaccines, knowledge gaps remain about the vaccination of children in special risk groups (SRG). This study aimed to analyze the clinical data of children vaccinated in SRG in a single-center unit to contribute to the clinical evidence for the specific planning of immunization of children in SRG. The second- ary aim is to present institutional consensus on the vaccination of children in SRG.

MATERIALS AND METHODS

This retrospective study was conducted at a single-center pediatric vaccination clinic. Patient charts between 2018 and 2021 were retrospectively reviewed, and clinical and laboratory data were extracted. Serial joint meetings with multiple healthcare pro- fessionals were performed to develop an institutional protocol for vaccination.

RESULTS

There were 479 children vaccinated between 2018 and 2021 for reasons such as post- chemotherapy, after hematopoietic stem cell transplantation, before/after solid organ trans- plantation, allergies, and chronic diseases. Of these, 298 (62.2%) children vaccinated in the unit due to a history of food or vaccine allergies were excluded. One hundred eighty-one children were vaccinated at a median age of 11 [7-15] years. Most children were vaccinated after treat- ment for malignancies. Solid tumors were the most frequent malignancy (67%), followed by acute lymphoblastic leukemia (29.0%) and acute myeloid leukemia (4.0%). Institutional vacci- nation protocols for cancer survivors, hematopoietic stem cells, and solid organ recipient chil- dren were developed and presented.

CONCLUSION

There is a need to prepare national guidelines for vaccinating children with altered immunocompetence. Sharing vaccination practices by multidisciplinary vaccination units might increase and provide knowledge to develop national policies.

Survey of pediatric transplant center practices regarding COVID-19 vaccine mandates for transplant candidates and living donors and use of COVID-19-positive deceased organs

BACKGROUND

COVID-19 vaccine is recommended for individuals ages ≥6 months; however, whether vaccination should be mandated for transplant candidates and living donors remains controversial. This study assessed COVID-19 policies at US pediatric solid organ transplant centers.

METHODS

A 79-item survey was emailed between March and April 2022 to 200 UNOS Medical Directors detailing center COVID-19 vaccine policies for transplant candidates and living donors and use of grafts from COVID-19-positive deceased donors.

RESULTS

The response rate was 77% (154/200). For children aged 5-15 years, 23% (35/154 centers) have a COVID-19 vaccine mandate, 27% (42/154) anticipate implementing a future mandate, and 47% (72/154) have not considered or do not anticipate implementing a mandate. For children ≥16 years, 32% (50/154 centers) have a COVID-19 vaccine mandate, 25% (39/154) anticipate implementing a future mandate, and 40% (62/154) have not considered or do not anticipate implementing a mandate. The top two reasons for not implementing a COVID-19 vaccine mandate were concerns about penalizing a child for their parent's decision and worsening inequities in transplant. Of 85 kidney and liver living donor centers, 32% (27/85) require vaccination of donors. Twenty percent (31/154) of centers accept organs from COVID-19-positive deceased donors.

CONCLUSIONS

There is great variation among pediatric SOT centers in both the implementation and details of COVID-19 vaccine mandates for candidates and living donors. To guide more uniform policies, further data are needed on COVID-19 disease, vaccine efficacy, and use of grafts from donors positive for COVID-19 in the pediatric transplant population.

High prevalence of hepatitis A and B nonimmunity in pediatric liver transplant recipients

BACKGROUND

Pediatric liver transplant recipients are at increased risk of post-transplant infections. The purpose of this study was to quantify hepatitis A and B non-immunity based on antibody titers in liver transplant recipients.

METHODS

We conducted a retrospective chart review of 107 pediatric liver transplant recipients at a single medical center from 2000 to 2017. We compared hepatitis immune patients to non-immune patients and studied response to vaccination in patients immunized post-transplantation.

RESULTS

Eighty-one percent of patients had pre-transplant immunity to hepatitis A whereas 68% had pre-transplant immunity to hepatitis B. Post-transplant hepatitis B immunity decreased to 33% whereas post-transplant hepatitis A immunity remained high at 82%. Older age and time since transplantation were significantly associated with hepatitis B non-immunity. Most patients responded to doses post-transplantation with 78% seroconversion following hepatitis A re-immunization and 83% seroconversion following hepatitis B re-immunization.

CONCLUSIONS

Pediatric liver transplant recipients are at risk of hepatitis A and B non-immunity, particularly with respect to hepatitis B. Boosters post-transplant may improve immunity to hepatitis viruses.

Immunization of Solid Organ Transplant Candidates and Recipients: A 2022 Update

Immunizations are a relatively safe and cost-effective intervention to prevent morbidity and mortality associated with vaccine preventable infection (VPIs). As such, immunizations are a critical part of the care of pre and posttransplant patients and should be prioritized. New tools are needed to continue to disseminate and implement the most up-to-date vaccine recommendations for the SOT population. These tools will help both primary care providers and multi-disciplinary transplant team members taking care of transplant patients to stay abreast of evidence-based best practices regarding the immunization of the SOT patient.

Bacteremia in Pediatric Liver Transplant Recipients

BACKGROUND

We aimed to determine the frequency of bacteremia, septic shock and bacterial meningitis in pediatric liver transplant recipients (pLTRs) in the outpatient setting and to identify clinical factors associated with bacteremia.

METHODS

Multicenter retrospective study of pLTRs evaluated in the emergency department or outpatient clinic between 2010 and 2018 for suspected infection, defined as fever ≥38 °C or a blood culture obtained. We excluded patients with nontransplant immunodeficiency, multiorgan transplants or intestinal failure. The primary outcome was bacteremia; secondary outcomes included fluid-refractory septic shock, bacterial meningitis and antibiotic resistance. The unit of analysis was the encounter.

RESULTS

A total of 151 children had 336 encounters for infection evaluation within 2 years of transplant. Of 307 (91.4%) encounters with blood cultures, 17 (5.5%) had bacteremia, with 10 (58.8%) occurring within 3 months of transplant. Fluid-refractory septic shock and bacterial meningitis occurred in 7 out of 307 (2.8%) and 0 out of 307 encounters, respectively. Factors associated with bacteremia included closer proximity to transplant (<3 months) [odds ratio (OR): 3.6; 95% confidence interval (CI): 1.3-9.8; P = 0.01], shorter duration of illness (OR: 4.3; 95% CI: 1.5-12.0; P < 0.01) and the presence of a central venous catheter (CVC) (OR: 12.7; 95% CI: 4.4-36.6; P < 0.01). However, 5 (29.4%) encounters with bacteremia had none of these factors. Among Gram-positive pathogens, 1 out of 7 (14.2%) isolates were resistant to vancomycin. Among Gram-negative pathogens, 3 out of 13 (23.1%) isolates were resistant to 3rd generation cephalosporins.

CONCLUSIONS

Bacteremia was an important cause of infection within 2 years of pLTR. Clinical factors increased the risk of bacteremia. Further, large sample studies should derive multivariable models to identify those at high and low risk of bacteremia to optimize antibiotic use.

Vaccine-Preventable Infections Among Solid Organ Transplant Recipients in Switzerland

Importance

Vaccine responses are decreased in solid organ transplant (SOT) recipients, and given the complexity of implementation, vaccination programs may be suboptimal. The actual burden of vaccine-preventable infections (VPIs) among SOT recipients remains unclear.

Objectives

To assess the incidence rate of VPIs among SOT recipients and to evaluate whether SOT recipients are at increased risk for specific VPIs compared with the general population.

Design, Setting, and Participants

This nationwide cohort study used data from the Swiss Transplant Cohort Study on VPIs in individuals who underwent SOT from May 2008 to June 2019 (follow-up until December 2019) and data from the Swiss Federal Office of Public Health on notifiable VPIs in the general population in the same period. Data were analyzed from January 2021 to June 2022.

Exposures

Solid organ transplant.

Main Outcomes and Measures

The main outcomes were the incidence rate of the following VPIs in SOT recipients: hepatitis A and B, diphtheria, Haemophilus influenzae infection, influenza, measles, mumps, pertussis, pneumococcal disease, poliomyelitis, meningococcal disease, rubella, tetanus, tick-borne encephalitis, and varicella zoster virus infection. Age-adjusted standardized incidence ratios were used to assess whether VPIs occurred more frequently in SOT recipients compared with the general population. For SOT recipients, factors associated with occurrence of VPIs were explored and the associated morbidity and mortality assessed.

Results

Of 4967 SOT recipients enrolled (median age, 54 years [IQR, 42-62 years]; 3191 [64.2%] male), 593 (11.9%) experienced at least 1 VPI. The overall VPI incidence rate was higher in the population that underwent SOT (30.57 per 1000 person-years [PY]; 95% CI, 28.24-33.10 per 1000 PY) compared with the general population (0.71 per 1000 PY). The standardized age-adjusted incidence ratio for notifiable VPIs in SOT recipients was higher compared with the general population (27.84; 95% CI, 25.00-31.00). In SOT recipients, influenza and varicella zoster virus infection accounted for most VPI episodes (16.55 per 1000 PY [95% CI, 14.85-18.46 per 1000 PY] and 12.83 per 1000 PY [95% CI, 11.40-14.44 per 1000 PY], respectively). A total of 198 of 575 VPI episodes in the population that underwent SOT (34.4%) led to hospital admission, and the occurrence of a VPI was associated with an increased risk for death and/or graft loss (hazard ratio, 2.44; 95% CI, 1.50-3.99; P = .002). In multivariable analysis, age 65 years or older at the time of transplant (incidence rate ratio [IRR], 1.29; 95% CI, 1.02-1.62) and receipt of a lung (IRR, 1.77; 95% CI, 1.38-2.26) or a heart (IRR, 1.40; 95% CI, 1.05-1.88) transplant were associated with an increased risk of VPI occurrence.

Conclusions and Relevance

In this study, 11.9% of SOT recipients experienced VPIs, and the incidence rate was higher than in the general population. There was significant morbidity and mortality associated with these infections in the population that underwent SOT, which highlights the need for optimizing immunization strategies.

[Vaccination coverage, beliefs, and attitudes in transplanted children and adolescents: a mixed-methods systematic review.]

OBJECTIVE

Vaccine-preventable infectious diseases are a cause of morbidity and mortality in transplanted children. The main objective of this study was to synthesize the available evidence of vaccination coverage in children and adolescents who are candidates or transplant recipients and to analyze beliefs, attitudes, and experiences about vaccination.

METHODS

A mixed-methods systematic review was performed (Open Science Framework registration: https://osf.io/auqn3/). Searches were conducted in PubMed/MEDLINE, EMBASE, IBECS and LILACS (from January 2000 to August 2021) and in gray literature. Quantitative and qualitative studies reported information on coverage, beliefs, attitudes and/or experiences about recommended vaccines in children who are candidates or recipients of solid organ or hematopoietic progenitor transplantation. Quality assessment was undertaken using Mixed Methods Appraisal Tool (MMAT). A narrative synthesis of the studies was carried out.

RESULTS

A total of thirty-two studies in thirty-five publications were included. The most studied interventions were vaccines against measles (n=21; 66%) and hepatitis B (n=20; 62%). Vaccination rates showed a high variability for the most represented vaccines (specifically, 2%-100% for measles, 0.4%-100% for hepatitis B, diphtheria-tetanus-pertussis and rubella), with coverages lower than 90% in at least 70% of the studies. The lowest rates were reported in post-transplantation and hematopoietic stem cell transplantation. Only one qualitative study was identified reporting information on beliefs and/or attitudes, although nine quantitative studies explored cognitive aspects.

CONCLUSIONS

This review shows a high variability in vaccination coverage in children and adolescents who are transplant candidates or recipients, with rates lower than those recommended. Further studies would be needed to identify beliefs and attitudes about immunization in this context.

Spotting a potential threat: Measles among pediatric solid organ transplantation recipients

BACKGROUND

Low-vaccination rates worldwide have led to the re-emergence of vaccine-preventable infections, including measles. Immunocompromised patients, including pediatric solid organ transplant (SOT) recipients, are at risk for measles because of suboptimal vaccination, reduced or waning vaccine immunity, lifelong immunosuppression, and global re-emergence of measles.

OBJECTIVES

To review published cases of measles in pediatric SOT recipients to heighten awareness of its clinical manifestations, summarize diagnostic and treatment strategies, and identify opportunities to optimize prevention.

METHODS

We conducted a literature review of published natural measles infections in SOT recipients ≤21 years of age, summarizing management and outcomes. We describe measles epidemiology, recommended diagnostics, treatment, and highlight prevention strategies.

RESULTS

There are seven published reports of measles infection in 12 pediatric SOT recipients, the majority of whom were unvaccinated or incompletely vaccinated. Subjects had atypical or severe clinical presentations, including lack of rash and complications, most frequently with encephalitis and pneumonitis, resulting in 33% mortality. Updated recommendations on testing and vaccination are provided. Treatment options beyond supportive care and vitamin A are limited, with no approved antivirals.

CONCLUSION

While measles is infrequently reported in pediatric SOT recipients, morbidity and mortality remain significant. A high index of suspicion is warranted in susceptible SOT recipients with clinically compatible illness or exposure. Providers must recognize this risk, educate families, and be aware of both classic and atypical presentations of measles to rapidly identify, isolate, and diagnose measles in pediatric SOT recipients. Continued efforts to optimize measles vaccination both pre- and post-SOT are warranted.

Incidence of and risk factors for influenza-associated hospital encounters in pediatric solid organ transplant recipients

Few studies have defined the incidence of and risk factors for influenza infection in pediatric solid organ transplant (SOT) recipients. We used a linkage between the Pediatric Health Information System and the Scientific Registry of Transplant Recipients databases to identify posttransplant influenza-associated hospital encounters (IAHEs) in pediatric SOT recipients of single-organ transplants. Among 7997 unique pediatric SOT recipients transplanted between January 01, 2006, and January 06, 2016, estimated 1- and 3-year posttransplant cumulative incidence rates of IAHEs were 2.7% (95% CI, 2.4%-3.1%) and 7.4% (95% CI, 6.8%-8.0%), respectively. One- and 3-year cumulative incidence rates of severe IAHEs were 0.3% (95% CI, 0.2%-0.5%) and 0.9% (95% CI, 0.7%-1.2%), respectively. Multivariable analysis showed that the organ type (adjusted subdistribution hazard ratio [aSHR]-kidney: reference, liver: 0.64 [95% CI, 0.49-0.84], and heart: 0.72 [95% CI, 0.57-0.93]), race/ethnicity (aSHR-non-Hispanic White: reference, non-Hispanic Black: 1.63 [95% CI, 1.29-2.07], Hispanic 1.57 [95% CI, 1.27-1.94]), and increasing age at transplant (aSHR, 0.93 [95% CI, 0.91-0.94]) were significantly associated with IAHE occurrence. Heart transplant recipients had a near statistically significant increase in hazard for severe IAHE (aSHR 1.96 [0.92-3.49]). Our findings may help guide future influenza prevention efforts and facilitate intervention impact assessment measurement in pediatric SOT recipients.

Frequency of Bacteremia and Urinary Tract Infection in Pediatric Renal Transplant Recipients

BACKGROUND

Our primary goal was to determine the frequency of bacteremia and urinary tract infections (UTI) in pediatric renal transplant recipients presenting with suspected infection within 2 years of transplant and to identify clinical and laboratory factors associated with bacteremia.

METHODS

We conducted a retrospective cross-sectional study for all pediatric ( < 18 years old) renal transplant recipients seen at 3 large children's hospitals from 2011 to 2018 for suspected infection within 2 years of transplant date, defined as pyrexia ( > 38°C) or a blood culture being ordered. Patients with primary immunodeficiencies, nontransplant immunosuppression, intestinal failure, and patients who had moved out of the local area were excluded. The primary outcome was bacteremia or UTI; secondary outcomes included pneumonia, bacterial or fungal meningitis, respiratory viral infections, and antibiotic resistance. The unit of analysis was the visit.

RESULTS

One hundred fifteen children had 267 visits for infection evaluation within 2 years of transplant. Bacteremia (with or without UTI) was diagnosed in 9/213 (4.2%) and UTIs in 63/189 (33.3%). Tachycardia and hypotension were present in 66.7% and 0% of visits with documented bacteremia, respectively. White blood cell (12,700 cells/mm 3 vs. 10,900 cells/mm 3 ; P = 0.43) and absolute neutrophil count (10,700 vs. 8200 cells/mm 3 ; P = 0.24) were no different in bacteremic and nonbacteremic patients. The absolute band count was higher in children with bacteremia (1900 vs. 600 cells/mm 3 ; P = 0.02). Among Gram-negative pathogens, antibiotic resistance was seen to 3rd (14.5%) and 4th (3.6%) generation cephalosporins, 12.7% to semisynthetic penicillins, and 3.6% to carbapenems.

CONCLUSIONS

Bacteremia or UTIs were diagnosed in one-quarter of all pediatric renal transplant recipients presenting with suspected infection within 2 years of transplant. Evaluations were highly variable, with one-third of visits not having urine cultures obtained. No single demographic, clinical or laboratory variable accurately identified patients with bacteremia, although combinations of findings may identify a high-risk population.

A brief guide to immunisation and the immunocompromised child or young person

Immunisation in children with a compromised immune system is not straightforward. Children with autoimmune disorders are especially at risk of vaccine-preventable diseases due to their underlying disease and the immunosuppressive treatment that is often required for a long period. This article explores some of the complexities that need to be considered when planning individual vaccination programmes.

Effect of influenza vaccination in solid organ transplant recipients: A nationwide population-based cohort study

Vaccination can prevent influenza in solid organ transplant (SOT) recipients. Using a modified season-specific approach over nine consecutive influenza seasons, we investigated influenza vaccination coverage and effectiveness in a population-based nationwide cohort study that included all SOT recipients aged ≥18 years who were living in Denmark from December 1, 2007 to April 1, 2016. The primary outcome was the season-specific risk of all-cause pneumonia admission. Secondary outcomes were season-specific influenza-related admission, intensive care unit (ICU) admission, and all-cause mortality. Crude and adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression models. In total, 11 381 person-years of follow-up data were collected from 5745 SOT recipients, 48% of whom were vaccinated. Influenza vaccination was associated with a reduced risk of all-cause pneumonia admission (aHR, 0.83; 95% CI, 0.69-0.99; p = .035) and all-cause mortality (aHR, 0.60; 95% CI, 0.47-0.76; p = .001), but not influenza-related admission (aHR, 0.75; 95% CI, 0.46-1.22; p = .24) or ICU admission (aHR, 0.84; 95% CI, 0.67-1.06; p = .14) during the same season. Despite these benefits, uptake of influenza vaccination among SOT recipients was low. Therefore, annual influenza vaccination needs to be prioritized.

Notifiable Infectious Diseases Among Organ Transplant Recipients: A Data-Linked Cohort Study, 2000–2015

Background

Infections, including common communicable infections such as influenza, frequently cause disease after organ transplantation, although the quantitative extent of infection and disease remains uncertain.

Methods

A cohort study was conducted to define the burden of notifiable infectious diseases among all solid organ recipients transplanted in New South Wales, Australia, 2000–2015. Data linkage was used to connect transplant registers to hospital admissions, notifiable diseases, and the death register. Standardized incidence ratios (SIRs) were calculated relative to general population notification rates, accounting for age, sex, and calendar year. Infection-related hospitalizations and deaths were identified.

Results

Among 4858 solid organ recipients followed for 39 183 person-years (PY), there were 792 notifications. Influenza was the most common infection (532 cases; incidence, 1358 [95% CI, 1247–1478] per 100 000 PY), highest within 3 months posttransplant. Next most common was salmonellosis (46 cases; incidence, 117 [95% CI, 87–156] per 100 000 PY), then pertussis (38 cases; incidence, 97 [95% CI, 71–133] per 100 000 PY). Influenza and invasive pneumococcal disease (IPD) showed significant excess cases compared with the general population (influenza SIR, 8.5 [95% CI, 7.8–9.2]; IPD SIR, 9.8 [95% CI, 6.9–13.9]), with high hospitalization rates (47% influenza cases, 68% IPD cases) and some mortality (4 influenza and 1 IPD deaths). By 10 years posttransplant, cumulative incidence of any vaccine-preventable disease was 12%, generally similar by transplanted organ, except higher among lung recipients. Gastrointestinal diseases, tuberculosis, and legionellosis had excess cases among transplant recipients, although there were few sexually transmitted infections and vector-borne diseases.

Conclusions

There is potential to avoid preventable infections among transplant recipients with improved vaccination programs, health education, and pretransplant donor and recipient screening.

The impact of COVID-19 on the pediatric solid organ transplant population

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has significantly impacted all aspects of healthcare including solid organ transplantation. In this review, we discuss the specific impact of COVID-19 on the pediatric solid organ transplant population including access to grafts for pediatric transplant candidates as well as COVID-19 disease manifestations in pediatric transplant recipients. We address the current knowledge of prevention and management of COVID-19 in pediatric transplant recipients and provide additional information regarding social distancing, infection prevention and return to school.

Live virus vaccination following pediatric liver transplantation: Outcomes from two academic children's hospitals

Pediatric liver transplant (LT) recipients are often transplanted at a young age, precluding them from receiving live virus vaccinations (LVV) such as varicella (VZV) vaccine and measles, mumps and rubella. This places them at profound risk for vaccine preventable illness. We sought to detail safety of vaccination. This was a retrospective cohort study of pediatric LT recipients at two children's hospitals. Among 204 LT recipients included in the study, 97 received at least one LVV after LT. Six patients who did not receive LVV after transplant had evidence of vaccine-preventable infection following vaccination (one disseminated VZV disease, five VZV-related rash), while one patient who received LVV after transplant developed a diffuse VZV-related rash. Rejection rates were the same between those that did and did not receive a live virus vaccine post-transplant. There were no serious adverse events caused by vaccination post-transplant. LVV following LT was safe at our two institutions, although there exist limitations in our study due to its retrospective study design. Larger scale studies should be performed to evaluate the effectiveness of LVV in relation to immunosuppression.

The case against COVID-19 vaccine mandates in pediatric solid organ transplantation

BACKGROUND

The American Society of Transplantation in conjunction with the International Society for Heart and Lung Transplantation released a joint statement on August 13, 2021 in which they strongly recommend that solid organ transplant (SOT) recipients and their eligible household members and close contacts be vaccinated against SARS-CoV-2 with an approved COVID-19 vaccine. Some SOT programs have gone further and will refuse to list or transplant candidates unless the candidate and their household are vaccinated against SARS-CoV-2.

METHODS

Two general pediatrician-ethicists use current best evidence and moral theory to argue why it is unethical to mandate COVID-19 vaccination for pediatric SOT candidates, their primary support person, and their households.

RESULTS

Pediatric vaccine mandates are most justifiable when they prevent the harm of a serious vaccine preventable disease (VPD) in children in settings where transmission is highly likely and there are no alternatives that are effective in preventing transmission that intrude less on individual freedom. An additional justification for a vaccine mandate in the SOT context is stewardship of a scarce resource if there is significant risk of graft loss from the VPD to an unvaccinated SOT candidate or recipient. Current evidence does not support fulfillment of these criteria in pediatric solid organ transplantation.

CONCLUSIONS

Making SOT listing contingent on COVID-19 vaccination is problematic. Though there is some risk of harm to a pediatric SOT candidate in remaining unvaccinated, the risk of harm of not being listed and transplanted is greater and overriding.

Long-Term Varicella Zoster Virus Immunity in Paediatric Liver Transplant Patients Can Be Achieved by Booster Vaccinations—A Single-Centre, Retrospective, Observational Analysis

Varicella is one of the most common vaccine-preventable infections after paediatric solid organ transplantation; thus, vaccination offers simple and cheap protection. However, children with liver disease often progress to liver transplantation (LT) before they reach the recommended vaccination age. As a live vaccine, varicella zoster virus (VZV) vaccination after transplantation is controversial; however, many case series demonstrate that vaccination may be safe and effective in paediatric liver transplant recipients. Only limited data exists describing long-term vaccination response in such immunocompromised patients. We investigated retrospectively vaccination response in paediatric patients before and after transplantation and describe long-term immunity over ten years, including the influence of booster-vaccinations. In this retrospective, single-centre study, 458 LT recipients were analysed between September 2004 and June 2021. Of these, 53 were re-transplantations. Patients with no available vaccination records and with a history of post-transplant lymphoproliferative disease, after hematopoietic stem cell transplantation and clinical chickenpox were excluded from this analysis (n = 198). In total, data on 207 children with a median annual follow-up of 6.2 years was available: 95 patients (45.9%) were unvaccinated prior to LT. Compared to healthy children, the response to vaccination, measured by seroconversion, is weaker in children with liver disease: almost 70% after one vaccination and 93% after two vaccinations. One year after transplantation, the mean titres and the number of children with protective antibody levels (VZV IgG ≥ 50 IU/L) decreased from 77.5% to 41.3%. Neither diagnosis, gender, nor age were predictors of vaccination response. Booster-vaccination was recommended for children after seroreversion using annual titre measurements and led to a significant increase in mean titre and number of protected children. Response to vaccination shows no difference from monotherapy with a calcineurin inhibitor to intensified immunosuppression by adding prednisolone or mycophenolate mofetil. Children with liver disease show weaker seroconversion rates to VZV vaccination compared to healthy children. Therefore, VZV-naïve children should receive basic immunization with two vaccine doses as well as those vaccinated only once before transplantation. An average of 2–3 vaccine doses are required in order to achieve a long-term seroconversion and protective antibody levels in 95% of children.

A Smartphone App to Increase Immunizations in the Pediatric Solid Organ Transplant Population: Development and Initial Usability Study

Background

Vaccine-preventable infections result in significant morbidity, mortality, and costs in pediatric transplant recipients. However, at the time of transplant, less than 20% of children are up-to-date for age-appropriate immunizations that could prevent these diseases. Smartphone apps have the potential to increase immunization rates through their ability to provide vaccine education, send vaccine reminders, and facilitate communication between parents and a multidisciplinary medical group.

Objective

The aim of this study was to describe the development of a smartphone app, Immunize PediatricTransplant, to promote pretransplant immunization and to report on app functionality and usability when applied to the target population.

Methods

We used a mixed methods study design guided by the Mobile Health Agile Development and Evaluation Lifecycle. We first completed a formative research including semistructured interviews with transplant stakeholders (12 primary care physicians, 40 parents or guardians of transplant recipients, 11 transplant nurse coordinators, and 19 transplant subspecialists) to explore the acceptability of an immunization app to be used in the pretransplant period. Based on these findings, CANImmunize Inc developed the Immunize PediatricTransplant app. We next held 2 focus group discussions with 5-6 transplant stakeholders/group (n=11; 5 parents of transplant recipients, 2 primary care physicians, 2 transplant nurse coordinators, and 2 transplant subspecialists) to receive feedback on the app. After the app modifications were made, alpha testing was conducted on the functional prototype. We then implemented beta testing with 12 stakeholders (6 parents of transplant recipients, 2 primary care doctors, 2 transplant nurse coordinators, and 2 transplant subspecialists) to refine the app through an iterative process. Finally, the stakeholders completed the user version of the Mobile Application Rating Scale (uMARS) to assess the functionality and quality of the app.

Results

A new Android- and Apple-compatible app, Immunize PediatricTransplant, was developed to improve immunization delivery in the pretransplant period. The app contains information about vaccine use in the pretransplant period, houses a complete immunization record for each child, includes a communication tool for parents and care providers, and sends automated reminders to parents and care providers when immunizations are due. During usability testing, the stakeholders were able to enter a mock vaccine record containing 16 vaccines in an average of 8.1 minutes (SD 1.8) with 87% accuracy. The stakeholders rated engagement, functionality, aesthetics, and information quality of the app as 4.2/5, 4.5/5, 4.6/5, and 4.8/5, respectively. All participants reported that they would recommend this app to families and care teams with a child awaiting solid organ transplant.

Conclusions

Through a systematic, user-centered, agile, iterative approach, the Immunize PediatricTransplant app was developed to improve immunization delivery in the pretransplant period. The app tested well with end users. Further testing and agile development among patients awaiting transplant are needed to understand real-world acceptability and effectiveness in improving immunization rates in children awaiting transplant.

Vaccination in pediatric solid organ transplant: A primer for the immunizing clinician

Pediatric solid organ transplant (SOT) recipients are at a uniquely elevated risk for vaccine preventable illness (VPI) secondary to a multitude of factors including incomplete immunization at the time of transplant, inadequate response to vaccines with immunosuppression, waning antibody titers observed post-SOT, and uncertainty among providers on the correct immunization schedule to utilize post-SOT. Multiple guidelines are in existence from the Infectious Diseases Society of America and the American Society of Transplantation, which require use in adjunct with additional published references. We summarize the present state of SOT vaccine recommendations from relevant resources in tandem with the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices guidance utilizing both routine and rapid catch-up schedules. The purpose of this all-inclusive review is to provide improved clarity on the most optimal pre- and post-transplant vaccine management within a one-stop-shop for the immunizing clinician. This article is protected by copyright. All rights reserved.

Considering a COVID-19 vaccine mandate for pediatric kidney transplant candidates

The world continues to face the effects of the SARS-CoV-2 pandemic. COVID-19 vaccines are safe and effective in protecting recipients, decreasing the risk of COVID-19 acquisition, transmission, hospitalization, and death. Transplant recipients may be at greater risk for severe SARS-CoV-2 infection. As a result, transplant programs have begun instituting mandates for COVID-19 vaccine for transplant candidacy. While the question of mandating COVID-19 vaccine for adult transplant candidates has garnered attention in the lay and academic press, these discussions have not explicitly addressed children who may be otherwise eligible for kidney transplants. In this paper we seek to examine the potential ethical justifications of a COVID-19 vaccine mandate for pediatric kidney transplant candidacy through an examination of relevant ethical principles, analogous cases of the use of mandates, differences between adult and pediatric kidney transplant candidates, and the role of gatekeeping in transplant vaccine mandates. At present, it does not appear that pediatric kidney transplant centers are justified to institute a COVID-19 vaccine mandate for candidates. Finally, we will offer suggestions to be considered prior to the implementation of a COVID-19 vaccine mandate.

Neonatal Cholestasis: Updates on Diagnostics, Therapeutics, and Prevention

Cholestatic jaundice is a common presenting feature of hepatobiliary and/or metabolic dysfunction in the newborn and young infant. Timely detection of cholestasis, followed by rapid step-wise evaluation to determine the etiology, is crucial to identify those causes that are amenable to medical or surgical intervention and to optimize outcomes for all infants. In the past 2 decades, genetic etiologies have been elucidated for many cholestatic diseases, and next-generation sequencing, whole-exome sequencing, and whole-genome sequencing now allow for relatively rapid and cost-effective diagnosis of conditions not previously identifiable via standard blood tests and/or liver biopsy. Advances have also been made in our understanding of risk factors for parenteral nutrition-associated cholestasis/liver disease. New lipid emulsion formulations, coupled with preventive measures to decrease central line-associated bloodstream infections, have resulted in lower rates of cholestasis and liver disease in infants and children receiving long-term parental nutrition. Unfortunately, little progress has been made in determining the exact cause of biliary atresia. The median age at the time of the hepatoportoenterostomy procedure is still greater than 60 days; consequently, biliary atresia remains the primary indication for pediatric liver transplantation. Several emerging therapies may reduce the bile acid load to the liver and improve outcomes in some neonatal cholestatic disorders. The goal of this article is to review the etiologies, diagnostic algorithms, and current and future management strategies for infants with cholestasis.

Quality improvement project to improve vaccinations in the pediatric liver transplant population

OBJECTIVES

A quality improvement approach was used to increase pediatric liver transplant recipient live and inactive vaccination rates by assessing titers and recommending vaccinations.

METHODS

A new screening and immunization process for both live and inactive vaccines was discussed with families at their annual visit. Antibody titers for varicella, measles, mumps, rubella, Haemophilus influenzae type B, hepatitis A, and hepatitis B were obtained. Specific criteria were developed for live virus vaccination candidacy. Vaccines were recommended based on patient titers and vaccination candidacy criteria. Surveillance for adverse effects to live vaccines was performed. Repeat titers were obtained approximately 1-month post-vaccine administration.

RESULTS

After PDSA cycle 1, 99% (71/72) of pediatric liver transplant patients had titers obtained. Live vaccines were recommended for 32 patients and 16 (50%) were vaccinated. Inactive vaccines were recommended to 64 patients, and 31 (48%) were vaccinated. Eight of 13 (62%) patients with follow-up titers achieved immunity for inactive vaccines. Zero patients had an adverse reaction to any live vaccine. Ten of 12 (83%) patients with follow-up titers achieved immunity from live vaccines. The most common barriers to receive live vaccines included not scheduling appointment with primary care provider (n = 3) and "non-vaccinators" (n = 3).

CONCLUSIONS

Administering live and inactive vaccines to select pediatric liver transplant patients appears to be safe and effective in our studied population. For PDSA cycle 2, we will continue our current practice and consider offering vaccines in transplant clinic, since this was a barrier to vaccination identified during PDSA cycle 1.

COVID-19 vaccination in pediatric solid organ transplant recipients-Current state and future directions

BACKGROUND

Population-level COVID-19 immunization will play a key role in slowing down the SARS-CoV-2 pandemic on a global scale and protect the most at-risk individuals. Thanks to a formidable universal effort, several SARS-CoV-2 vaccines have been marketed less than a year since the first documented COVID-19 case, with promising safety, efficacy, and immunogenicity results in adults. As children were not included in the initial trials, no vaccine is currently approved for individuals <16 years of age. Similarly, immunosuppressed individuals, such as solid organ transplant recipients, were excluded from initial vaccine trials, limiting the understanding of vaccine immunogenicity and safety in this at-risk population. Thus, data regarding COVID-19 vaccination in pediatric solid organ transplantation recipients are currently lacking.

METHODS

Members of the International Pediatric Transplant Association review the current general status of COVID-19 vaccines focusing on pediatric-specific issues.

RESULTS

This review provides an overview of COVID-19 vaccines in pediatric SOT recipients and highlights the current paucity of data in both pediatric and transplant settings in terms of safety, immunogenicity, and clinical efficacy.

CONCLUSIONS

Vaccine trials including children and transplant recipients are underway and will be necessary to characterize COVID-19 vaccine safety, immunogenicity, and efficacy, which will determine potential future research directions.

Hospitalizations for Respiratory Syncytial Virus and Vaccine Preventable Infections following Pediatric Heart Transplantation

OBJECTIVE

To determine the risk factors for acquiring a respiratory syncytial virus (RSV) and vaccine-preventable infections (R/VPI) in pediatric heart transplant recipients and the associated morbidity and hospital resource use.

STUDY DESIGN

Patients <18 years who underwent heart transplantation from September 2003 to December 2018 at hospitals using the Pediatric Health Information System database were identified. Their transplant hospitalization and subsequent hospitalizations for R/VPI through December 2018 were analyzed. Risk factors for R/VPI hospitalizations were evaluated using negative regression binomial models adjusted for demographic and clinical confounders. Total hospital costs were adjusted for 2018 US$.

RESULTS

Of 3815 transplant recipients, 681 (17.9%) had an R/VPI hospitalization during 23 746 available person-years of follow-up. There were 984 R/VPIs diagnosed during 951 hospitalizations, and 440 (44.7%) occurred the first year after transplantation. The most common causes were RSV (n = 380; 38.6%), influenza (n = 265; 26.9%), and pneumococcus (n = 105; 10.7%). In adjusted analyses, there was an increased risk of R/VPI hospitalization in patients requiring mechanical circulatory support before transplantation, patients receiving induction with ≥2 immunosuppressive agents, and patients <2 years in the first year after transplantation. The median length of stay for an R/VPI hospitalization was 4 days (IQR, 2-8 days) with a median total cost of $11 081 (IQR, $6215-$24 322).

CONCLUSIONS

Hospitalization for R/VPIs occurred frequently after heart transplantation and were associated with significant costs. Potential strategies to minimize R/VPI include expanding vaccine use through accelerated immunization schedules, further studies of use of palivizumab beyond 2 years of age, and immunogenicity monitoring after vaccination with re-immunization based on guidelines.

Under-Vaccination in Pediatric Liver Transplant Candidates with Acute and Chronic Liver Disease—A Retrospective Observational Study of the European Reference Network TransplantChild

Infection is a serious concern in the short and long term after pediatric liver transplantation. Vaccination represents an easy and cheap opportunity to reduce morbidity and mortality due to vaccine-preventable infection. This retrospective, observational, multi-center study examines the immunization status in pediatric liver transplant candidates at the time of transplantation and compares it to a control group of children with acute liver disease. Findings show only 80% were vaccinated age-appropriately, defined as having received the recommended number of vaccination doses for their age prior to transplantation; for DTP-PV-Hib, less than 75% for Hepatitis B and two-thirds for pneumococcal conjugate vaccine in children with chronic liver disease. Vaccination coverage for live vaccines is better compared to the acute control group with 81% versus 62% for measles, mumps and rubella (p = 0.003) and 65% versus 55% for varicella (p = 0.171). Nevertheless, a country-specific comparison with national reference data suggests a lower vaccination coverage in children with chronic liver disease. Our study reveals an under-vaccination in this high-risk group prior to transplantation and underlines the need to improve vaccination.

Prevention of infection and optimizing vaccination in the solid organ transplant candidate and recipient

PURPOSE OF REVIEW

Infections can result in serious complications in solid organ transplant (SOT) patients. The need to remain up to date on recommendations on screening, vaccinations, and chemoprophylaxis is paramount in the management of SOT patients. The goal of this review is to provide an overview of current recommendations for the prevention of infections and optimization of vaccinations from the pretransplant through posttransplant periods.

RECENT FINDINGS

There is an emphasis on thorough pretransplant evaluation to guide clinicians and pretransplant testing based on epidemiological and endemic risk factors. Additionally, recent studies on vaccine safety and efficacy of newer vaccine formulations in SOT recipients are addressed.

SUMMARY

This review provides insight on updated recommendations for pretransplant screening, new data on vaccine optimization in SOT recipients and posttransplant prophylaxis. Further research is needed in order to improve preventive measures including screening tests, vaccines, and chemoprophylaxis.

Gaps in knowledge about the vaccine coverage of immunocompromised children: a scoping review

Immunocompromised children are at increased risk of severe illness from vaccine-preventable infections. However, inadequate vaccine coverage remains a concern. This scoping review sought to determine the current state of knowledge regarding vaccine coverage of immunocompromised children. Bibliographic databases were searched for primary research from any year. Data were analyzed quantitatively and narratively. Ninety-seven studies met inclusion criteria. The most commonly studied vaccines were pneumococcal (n = 46), influenza (n = 44), diphtheria/tetanus/pertussis/poliomyelitis/Haemophilus influenzae type B/hepatitis B-containing (n = 36), and measles- and/or mumps- and/or rubella-containing (n = 29). Immunocompromising conditions studied included cancer/stem cell transplants (n = 24), solid organ transplants (n = 23), sickle cell disease (n = 21), immunosuppressive therapy (n = 14), human immunodeficiency virus (n = 12), splenectomy (n = 4), and primary immunodeficiency (n = 2). As more children are treated with immunosuppressive therapies, it is critical to identify whether they are being appropriately vaccinated for age and condition. We identified gaps in the current state of knowledge for specific vaccine types in specific immunocompromised populations.

Live virus vaccination of pediatric solid organ transplant candidates within 1 month prior to transplantation: A multicenter experience

BACKGROUND

Solid organ transplant (SOT) recipients are at increased risk of vaccine-preventable illness due to the high degree of immunosuppression required following transplantation. The current recommendation is to vaccinate with live attenuated vaccines, including Measles, Mumps, and Rubella (MMR) and Varicella (VAR) vaccines, at least 4 weeks prior to transplant. However, data to support the time interval between vaccine and transplant are limited.

METHODS

We conduct a literature review of the natural history of the viruses and length of viremia following live-attenuated viral vaccines, and we describe a series of 5 cases from 2 pediatric transplant centers in which live attenuated viral vaccines were administered within 21 days prior to SOT.

RESULTS

None of the 5 children who received MMR or VAR 8-21 days prior to liver (2) and heart (3) transplant suffered from vaccine-related viral illness after transplant, even in the presence of significant immunosuppression with T-cell-depleting agents.

CONCLUSION

These cases support that shorter intervals of live vaccine administration prior to transplant may be safe, allowing the vaccination of a larger cohort of SOT candidates. Increasing pretransplant vaccinations is crucial since, in most cases, live viral vaccines are contraindicated posttransplantation, and the most effective vaccine approaches utilize prime-boost strategies, priming before and boosting after transplant.

Bacterial and fungal bloodstream infections in pediatric liver and kidney transplant recipients

Background

Bacterial and fungal bloodstream infections (BSI) are common after pediatric liver and kidney transplantations and associated with morbidity and mortality. However, knowledge about incidence rates, pathogen composition, and resistance patterns is limited. We aimed to describe the pattern of bacterial and fungal BSI in a cohort of pediatric liver and kidney transplant recipients.

Methods

A prospective study of 85 pediatric liver and kidney transplant recipients transplanted from 2010 to 2017 with a total of 390 person-years of follow-up. Clinical characteristics and BSI were retrieved from national registries assuring nationwide follow-up for at least 1 year. BSI incidence rates and pathogen composition were investigated and stratified by the time post-transplantation and type of transplanted organ.

Results

A total of 29 BSI were observed within the first 5 years post-transplantation with 16 different pathogens. The overall incidence rate of first BSI was 1.91 per 100 recipients per month (95% CI, 1.1–3.1) in the first year post-transplantation. The most common pathogens were Enterococcus faecium, Candida albicans, Escherichia coli, and Klebsiella pneumoniae. The pathogen composition depended on the transplanted organ with a higher proportion of BSI with Enterobacterales in kidney transplant recipients than in liver transplant recipients (67% vs. 20%, p = 0.03), while multiple pathogens were detected in the liver transplant recipients.

Conclusions

BSI were common in pediatric liver and kidney transplant recipients and the pathogen composition differed between liver and kidney transplant recipients. Guidelines for empiric antibiotic therapy should consider the type of transplanted organ as well as the local resistance patterns.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06224-2.

Alternative strategies of posttransplant influenza vaccination in adult solid organ transplant recipients

Solid organ transplant (SOT) recipients are at increased risk of influenza disease and associated complications. The mainstay of prevention is the annual standard-dose influenza vaccine, as studies showed decreased influenza-related morbidity and mortality in vaccinated SOT recipients compared to those unvaccinated. Nonetheless, the immune response in this high-risk population is suboptimal compared to healthy individuals. Over the past two decades, several vaccination strategies have been investigated to overcome this inadequate immune response in SOT recipients. Howbeit, the best vaccination strategy and optimal timing of influenza vaccination remain unclear. This review will provide a detailed summary of studies of various influenza vaccination strategies in adult SOT recipients, discussing immunogenicity results, and addressing their limitations and knowledge gaps.

Immunization status and hospitalization for vaccine-preventable and non-vaccine-preventable infections in liver-transplanted children

BACKGROUND

Infections and associated morbidity and mortality may be more frequent in children who have undergone liver transplant than in healthy children. Immunization strategies to prevent vaccine-preventable infections (VPIs) can effectively minimize this infection burden. However, data on age-appropriate immunization and VPIs in children after liver transplant in Asia are limited.

AIM

To evaluate the immunization status, VPIs and non-VPIs requiring hospitalization in children who have undergone a liver transplant.

METHODS

The medical records of children who had a liver transplant between 2004 and 2018 at King Chulalongkorn Memorial Hospital (Bangkok, Thailand) were retrospectively reviewed. Immunization status was evaluated via their vaccination books. Hospitalization for infections that occurred up to 5 years after liver transplantation were evaluated, and divided into VPIs and non-VPIs. Hospitalizations for cytomegalovirus and Epstein-Barr virus were excluded. Severity of infection, length of hospital stay, ventilator support, intensive care unit requirement, and mortality were assessed.

RESULTS

Seventy-seven children with a mean age of 3.29 ± 4.17 years were included in the study, of whom 41 (53.2%) were female. The mean follow-up duration was 3.68 ± 1.45 years. Fortyeight children (62.3%) had vaccination records. There was a significant difference in the proportion of children with incomplete vaccination according to Thailand’s Expanded Program on Immunization (52.0%) and accelerated vaccine from Infectious Diseases Society of America (89.5%) (P < 0.001). Post-liver transplant, 47.9% of the children did not catch up with age-appropriate immunizations. There were 237 infections requiring hospitalization during the 5 years of follow-up. There were no significant differences in hospitalization for VPIs or non-VPIs in children with complete and incomplete immunizations. The risk of serious infection was high in the first year after receiving a liver transplant, and two children died. Respiratory and gastrointestinal systems were common sites of infection. The most common pathogens that caused VPIs were rotavirus, influenza virus, and varicella-zoster virus.

CONCLUSION

Incomplete immunization was common pre- and post-transplant, and nearly all children required hospitalization for non-VPIs or VPIs within 5 years post-transplant. Infection severity was high in the first year post-transplant.

Seroprevalence of Antibodies against Diphtheria, Tetanus and Pertussis in Adult At-Risk Patients

Patients with chronic diseases are at increased risk of complications following infection. It remains, however, unknown to what extend they are protected against vaccine-preventable diseases. We assessed seroprevalence of antibodies against diphtheria, tetanus and pertussis to evaluate whether current vaccination programs in Belgium are adequate. Antibody titers were assessed with a bead-based multiplex assay in serum of 1052 adults with chronic diseases. We included patients with diabetes mellitus type 1 (DM1) (n = 172), DM2 (n = 77), chronic kidney disease (n = 130), chronic obstructive pulmonary disease (COPD) (n = 170), heart failure (n = 77), HIV (n = 196) and solid organ transplant (SOT) recipients (n = 230). Factors associated with seroprevalence were analysed with multiple logistic regression. We found seroprotective titers in 29% for diphtheria (≥0.1 IU/mL), in 83% for tetanus (≥0.1 IU/mL) and 22% had antibodies against pertussis (≥5 IU/mL). Seroprotection rates were higher (p < 0.001) when vaccinated within the last ten years. Furthermore, diphtheria seroprotection decreased with age (p < 0.001). Tetanus seroprotection was less reached in women (p < 0.001) and older age groups (p < 0.001). For pertussis, women had more often a titer suggestive of a recent infection or vaccination (≥100 IU/mL, p < 0.01). We conclude that except for tetanus, the vast majority of at-risk patients remains susceptible to vaccine-preventable diseases such as diphtheria and pertussis.

Vaccination of immune compromised children-an overview for physicians

Immune compromised children are threatened by a higher risk of infections; some of these are preventable by vaccination. Primary care physicians play a fundamental role in optimising vaccination status. In this narrative review, we present the evidence on vaccine safety and immunogenicity in immune compromised children and discuss in which conditions live-attenuated vaccines can possibly be used. Vaccination schedules differ in some of these conditions, including the use of vaccines with higher antigenic contents (e.g. high-dose hepatitis B vaccine), additional vaccine doses (e.g. 2-dose schedule meningococcal vaccine), more frequent booster doses (e.g. life-long pneumococcal vaccine booster), supplementary vaccines (e.g. meningococcal B vaccine) and use of vaccines beyond the age of usual recommendation (e.g. Haemophilus influenza type b vaccine after 5 years of age). Serological monitoring is a useful tool for customizing vaccination schedule in immune compromised children, confirming adequate vaccine response and documenting seroprotection (especially against measles and varicella). Finally, verification of vaccination status of all household members can prevent them being vector of transmission of an infection to the immune compromised children. Conclusion: Intensified information strategies are needed to improve trust, rectify perceived risks and improve vaccine acceptability; primary physicians can play a critical role in the latter. What is Known: • Physician's awareness is key to success, since it repeatedly correlates with higher vaccination rates What is New: • The vaccination status of immunocompromised children is rarely up-to-date • Knowing the latest vaccine recommendations is challenging, as they differ for each medical condition and change periodically • This review summarises the vaccine recommendations for children with compromised immune systems and highlights how paediatricians play a key role in coordinating their application.

Barriers to Pretransplant Immunization: A Qualitative Interview Study of Pediatric Solid Organ Transplant Stakeholders

OBJECTIVES

To describe the experiences and beliefs of pediatric transplant stakeholders regarding factors that contribute to low pretransplant immunization rates.

STUDY DESIGN

Semistructured interviews were conducted with transplant team members (hepatologists, cardiologists, nephrologists, transplant nurse coordinators, and transplant infectious diseases physicians), primary care physicians, and parents of heart, liver, and kidney transplant recipients at 3 geographically diverse large pediatric transplant centers in the US. Interviews were conducted between July 2017 and February 2020 until thematic saturation was reached within each stakeholder subgroup. Content analysis methodology was used to identify themes.

RESULTS

Stakeholders participated in 30- to 60-minute interviews (16 transplant subspecialists, 3 transplant infectious diseases physicians, 11 transplant nurse coordinators, 12 primary care physicians, and 40 parents). Five central themes emerged: (1) gaps in knowledge about timing and safety of pretransplant immunizations, (2) lack of communication, coordination, and follow-up between team members regarding immunizations, (3) lack of centralized immunization records, (4) subspecialty clinic functioning as the medical home for transplant candidates but unable to provide all needed immunizations, and (5) differences between organ type in prioritization and completion of pretransplant immunization.

CONCLUSIONS

There are multiple factors that contribute to low immunization rates among pediatric transplant candidates. New tools are needed to overcome these barriers and increase immunization rates in transplant candidates.

Return to School for Pediatric Solid Organ Transplant Recipients in the United States During the Coronavirus Disease 2019 Pandemic: Expert Opinion on Key Considerations and Best Practices

The coronavirus disease 2019 (COVID-19) pandemic has created many challenges for pediatric solid organ transplant (SOT) recipients and their families. As the pandemic persists, patients and their families struggle to identify the best and safest practices for resuming activities as areas reopen. Notably, decisions about returning to school remain difficult. We assembled a team of pediatric infectious diseases (ID), transplant ID, public health, transplant psychology, and infection prevention and control specialists to address the primary concerns about school reentry for pediatric SOT recipients in the United States. Based on available literature and guidance from national organizations, we generated consensus statements pertaining to school reentry specific to pediatric SOT recipients. Although data are limited and the COVID-19 pandemic is highly dynamic, our goal was to create a framework from which providers and caregivers can identify the most important considerations for each pediatric SOT recipient to promote a safe return to school.

The Importance of Prioritizing Pre and Posttransplant Immunizations in an Era of Vaccine Refusal and Epidemic Outbreaks

Vaccine-preventable infections are occurring at epidemic rates both nationally and internationally. At the same time, rates of vaccine hesitancy and refusal are increasing across the country leading to decreased herd immunity. For immunosuppressed transplant recipients, this situation poses great risk. Currently, 1 in 6 pediatric solid organ transplant recipients is hospitalized with a vaccine-preventable infection in the first 5 years posttransplant. For many recipients, these infections result in significant morbidity, mortality, and increased hospitalization costs. Surprisingly, despite this risk many transplant recipients are not up-to-date on age appropriate immunizations at the time of transplant and thereafter. As a transplant community, we must prioritize immunizations in both pre and posttransplant care. Research is needed to understand how to monitor immune response to vaccines in immunosuppressed patients and when to optimally immunize patients posttransplant. Finally, recommendations about administration of live vaccines posttransplant may need to be reevaluated in the setting of measles outbreaks and decreased herd immunity.

Persistent hypogammaglobulinemia in pediatric solid organ transplant recipients

INTRODUCTION

Hypogammaglobulinemia has not been well studied in pediatric solid organ transplant (SOT) recipients. We evaluated plasma immunoglobulin (Ig) and lymphocyte phenotypes among 31 pediatric heart and kidney recipients for two years post-transplant and from 10 non-transplanted children.

METHODS

Plasma IgM, IgG, and IgA were quantified by immunoturbidimetric assays, IgG subclasses were quantified by bead-based multiplex immunoassay, and lymphocyte phenotypes were assessed by flow cytometry.

RESULTS

Median age at transplant for SOT recipients was similar to that of the control cohort (15 vs. 12.5 years, respectively; P = .61). Mean plasma IgG and IgM levels for SOT recipients fell significantly below the control cohort means by 1 month post-transplant (P < .001 for both) and remained lower than control levels at 12-18 months post-transplant. Heart recipients had lower frequencies of a CD4⁺ naïve T lymphocytes relative to kidney recipients.

CONCLUSIONS

Hypogammaglobulinemia was prevalent and persistent among pediatric SOT recipients and may be secondary to immunosuppressive medications, as well as loss of thymus tissue and CD45RA⁺   CD4⁺ T cells in heart recipients. Limitations of our study include but are not limited to small sample size from a single center, lack of samples for all participants at every time point, and lack of peripheral blood mononuclear cell samples for the non-transplanted cohort.

Underimmunization of the solid organ transplant population: An urgent problem with potential digital health solutions

Solid organ transplant recipients are at risk for potentially life-threatening infections due to lifelong immunosuppression. Vaccine-preventable infections result in graft injury, morbidity, mortality, and significantly increased medical costs. Unfortunately, the majority of transplant recipients continue to be underimmunized at the time of transplant and thereafter. Given the rising rates of vaccine hesitancy and refusal in the general population, transplant recipients can no longer rely on herd immunity to protect them from vaccine-preventable infections. Novel tools are desperately needed to overcome transplant-specific immunization barriers to improve immunization rates in this high-risk population. Digital health technologies may offer a solution by addressing transplant-specific barriers: specifically, providing accurate information about vaccine safety, efficacy, and timing in the pre- and posttransplant periods; making a complete immunization record universally available and easily accessible; enabling communication between patients and multiple providers; and providing automated vaccine reminders to both patients and providers when vaccines are due using transplant-specific immunization guidelines. Digital health has transformed health care by empowering patients with their own health information and connecting patients, their providers, and public health officials. In doing so, it offers a potential platform to address and overcome the problem of underimmunization in the transplant population.

Intracoronary Sarcoplasmic Reticulum Calcium-ATPase Gene Therapy in Advanced Heart Failure Patients with reduced Ejection Fraction: A Prospective Cohort Study

OBJECTIVE

Heart failure is a progressive and debilitating disease. Intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy may improve the function of cardiac muscle cells. This study aimed to test the hypothesis that intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy can improve outcomes and reduce the number of recurrent and terminal events in advanced heart failure patients with reduced ejection fraction.

METHODS

A total of 768 heart failure patients with reduced ejection fraction and New York Heart Association classification II to IV were included in this prospective cohort study. Patients either underwent intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy (CA group, n=384) or received oral placebo (PA group; n=384). Data regarding recurrent and terminal event(s), treatment-emergent adverse effects, and outcome measures were collected and analyzed.

RESULTS

After a follow-up period of 18 months, intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy reduced the number of hospital admissions (p=0.001), ambulatory treatments (p=0.0004), and deaths (p=0.024). Additionally, intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy improved the left ventricular ejection fraction (p<0.0001) and Kansas City Cardiomyopathy Questionnaire score (p<0.0001). The number of recurrent and terminal events/patients were higher in the PA group than in the CA group after the follow-up period of 18 months (p=0.015). The effect of the intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy was independent of the confounding variables. No new arrhythmias were reported in the CA group.

CONCLUSIONS

Intracoronary sarcoplasmic reticulum calcium-ATPase gene therapy reduces the number of recurrent and terminal events and improves the clinical course of advanced heart failure patients with reduced ejection fraction.

Impact of COVID-19 Pandemic on Pediatrics and Pediatric Transplantation Programs

COVID-19 has dramatically altered the health care landscape and disrupted global health and world economics in ways that are still being measured. Its impact on children with chronic conditions or those undergoing transplantation is evolving. The organ specific manifestations in children will be reviewed and treatment strategies outlined. The impact on pediatric transplantation in the United States over the initial 6 months of the pandemic has shown significant regional variation and lags persist in resumption of normal transplant activity, particularly for living related transplantation. Finally, guidelines regarding return to school will be discussed.