Live vaccines after pediatric solid organ transplant: Proceedings of a consensus meeting, 2018

Vaccination for solid organ transplanted patients: Recommendations, efficacy, and safety

Solid organ transplant recipients face unique challenges in managing their immunosuppressed status, making vaccination a critical consideration. This review aimed to comprehensively analyze current recommendations, evaluate the efficacy of vaccinations in this population, and assess safety concerns. We explored the latest evidence on vaccine types, timing, and potential benefits for transplant patients, highlighting the importance of individualized approaches for routinely used vaccines as well as coronavirus disease 2019 vaccines. By synthesizing available data, this review underscored the pressing need to optimize vaccination strategies, ensuring that transplant recipients can obtain the full protection against many pathogens while minimizing risks associated with their post-transplant immunosuppression.

Vaccinations in Paediatric Solid Organ Transplant Candidates and Recipients

Solid organ transplant (SOT) candidates and recipients are a fragile population, in which the presence of a pre-transplant disease leading to organ insufficiency and the post-transplant immunosuppressive treatment expose them to an increased risk of infectious diseases. The best intervention to guarantee efficient prevention of infections, with optimal cost-benefit ratio, is represented by vaccination programs; however, the response to vaccines needs that the immune system maintains a good function. This is even more relevant at paediatric age, when specific immunological conditions make transplant candidates and recipients particularly vulnerable. Paediatric patients may be naïve to most infections and may have incomplete immunization status at the time of transplant listing due to their age. Moreover, the unaccomplished development of a mature immune system and the immunosuppressive regimen adopted after transplant might affect the efficacy of post-transplant vaccinations. Therefore, every effort should be made to obtain the widest vaccination coverage before the transplantation, whenever possible. This review reports the most relevant literature, providing information on the current approach to the vaccinations in paediatric SOT candidates and recipients.

Live Vaccine and Varicella Postexposure Prophylaxis in Pediatric Liver Transplant Recipients: A Survey of Practice in Australia and New Zealand

BACKGROUND

Administration of live vaccines following liver transplant (LT) has historically not been recommended due to concerns regarding risk of vaccine-attenuated disease. However, there is evidence suggesting that in select transplant recipients live vaccinations can be administered safely. Studies in other regions have indicated that despite this evidence many clinicians remain hesitant to administer live vaccinations.

METHOD

A REDCap survey was distributed to gastroenterologists, pediatricians, and infectious diseases physicians at pediatric centers across Australia and New Zealand via email between September and November 2023. The survey included a series of questions regarding live vaccine and varicella postexposure prophylaxis (PEP) practices in pediatric LT recipients and barriers to live vaccine administration in this cohort.

RESULTS

There was a total of 16 responses to the survey, from 10 different pediatric centers, including 10/11 pediatric gastroenterology centers and all four pediatric LT centers in the region. Only 31% (5/16) of respondents (from 3/10 different centers) offer live vaccines. The main barrier to live vaccine administration was clinician reluctance and the main reason for not offering live vaccines was insufficient safety data. Sixty-nine percent (11/16) of respondents take vaccination status and/or serology into account when deciding whether to offer varicella PEP to this cohort. Respondents universally offer varicella zoster immunoglobulin as PEP, though 31% (5/16) also offer antiviral medication.

CONCLUSIONS

Many clinicians in our region remain hesitant to provide live vaccines to pediatric LT recipients, with concerns regarding insufficient safety data. Updated local guidelines may help to address this.

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.

Long-term persistence of seroprotection against measles following measles-mumps-rubella vaccination administered before and after pediatric liver transplantation

Liver transplant (LT) recipients are susceptible to infections, including measles. Concerns about the safety and efficacy of live-attenuated vaccines, such as the measles-mumps-rubella (MMR) vaccine, have led to hesitancy among providers in administering them to immunocompromised patients. This 9-year interventional study assessed seroprotection against measles following MMR vaccination in pediatric LT recipients. Of 119 participants enrolled, 60 (50%) were seroprotected against measles after transplantation. Among the 59 non-seroprotected participants, 56 fulfilled safety criteria and received MMR vaccination with a seroprotection rate of 90% (95%CI 73-98%) after a first dose, 95% (95%CI 85-99%) after primary vaccination with 1 to 3 doses, comparable to non-immunocompromised populations. However, measles antibodies declined over time, suggesting the need for regular monitoring, and booster doses. Half of the vaccinees (26/53, 49%) subsequently lost seroprotection. Among them, 23 received additional doses of MMR, with high seroconversion rate. At their last follow up (median 6.1 years, IQR 3.0-8.1 after inclusion), 63% (95%CI 49-75%) of all vaccinees were seroprotected against measles. In conclusion, MMR vaccination in pediatric LT recipients offers seroprotection against measles, but long-term immunity should be monitored closely. CLINICAL TRIAL REGISTRATION: The trial is registered at the US National Institutes of Health (Clinicaltrials.gov) number NCT01770119.

Detection of viral RNA and DNA and immune response following administration of live attenuated measles and varicella vaccines in children with chronic liver disease

Infections preventable by live virus vaccines are surging in the setting of decreased herd immunity. Many children with chronic liver diseases (CLDs) are unimmunized and at increased risk for infection due to guidelines recommending against live vaccines within 4 weeks pretransplant. This prospective study of 21 children with CLD and 13 healthy controls defined the timing of measles virus and varicella-zoster virus (VZV) RNA- and DNA-emia following vaccination and compared immune responses to measles and varicella vaccines in both groups. Measles virus RNA and VZV DNA real-time PCR were measured weekly following vaccination; measles virus RNA was undetectable in all by 14 days postvaccination, but VZV DNA, which can be managed with antivirals, was detected in 1 child in the CLD group at 21 days and 1 control at 28 days postvaccination. Humoral or cell-mediated vaccine response was 100% to measles virus and 94% to VZV in the CLD group postvaccination, whereas it was 100% to both vaccines in controls. Our pilot study suggests that both live vaccines can be safely and effectively administered up to 14 days prior to transplantation in children with CLD. We anticipate this will improve vaccination rates and thus decrease rates of vaccine-preventable infections in vulnerable children with CLD.

Infections After Liver Transplant -Timeline, Management and Prevention

Liver transplantation (LT) is the standard treatment for end- stage liver disease. Patient and graft survival have improved significantly in the last three decades owing to improvement in surgical technique, better perioperative management and better immunosuppressive regimens. However, LT recipients are at increased risk of infections, particularly in the first year after transplantation. The risk of infection is directly proportional to immunosuppressive regimen and graft function. In this review, we will briefly discuss the timeline of infections after liver transplant, preventive strategies and management of infectious complications.

Live-Attenuated Vaccines in Pediatric Solid Organ Transplant

Measles, mumps, rubella (MMR), and varicella incidence rates have increased due to the delayed vaccination schedules of children secondary to the COVID-19 pandemic. Decreased herd immunity creates a risk for immunocompetent children and immunocompromised individuals in the community. Historically, live-attenuated vaccines (MMR and varicella) were recommended before solid organ transplants. The amount of time before transplant when this is appropriate is often debated, as is the utility of vaccine titers. MMR and varicella vaccines previously were not recommended in immunocompromised patients post-solid organ transplant due to the undue risk of transmission and posed infection risk. The new literature on live-attenuated vaccines in post-transplant pediatric patients provides more insight into the vaccines' safety and efficacy. The present article aims to provide guidance on live-attenuated vaccines (MMR and varicella) in the pre-transplant and post-operative solid organ transplant phases of care in pediatric patients.

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.

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.

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.

Vaccination practices in pediatric transplantation: A survey among member centers of the European reference network TransplantChild

BACKGROUND

There is considerable variation in vaccination practices between pediatric transplant centers. This study aims to evaluate active immunization attitudes and practices among ERN-TransplantChild centers and identify potential areas of improvement that could be addressed by shared evidence-based protocols.

METHODS

A cross-sectional questionnaire of attitudes and practices toward immunization of pediatric SOT and HSCT candidates and recipients was sent to a representative member of multidisciplinary teams from 27 European centers belonging to the ERN-TransplantChild.

RESULTS

A total of 28/62 SOT programs and 6/12 HSCT programs across 21 European centers participated. A quarter of centers did not have an on-site protocol for the immunizations. At the time of transplantation, pediatric candidates were fully immunized (80%-100%) in 57% and 33% of the SOT and HSCT programs. Variations in the time between vaccine administration and admission to the waiting list were reported between the centers, with 2 weeks for inactivated vaccines and variable time (2-4 weeks) for live-attenuated vaccines (LAVs). Almost all sites recommended immunization in the post-transplant period, with a time window of 4-8 months for the inactivated vaccines and 16-24 months for MMR and Varicella vaccines. Only five sites administer LAVs after transplantation, with seroconversion evaluated in 80% of cases.

CONCLUSIONS

The immunization coverage of European pediatric transplant recipients is still inconsistent and far from adequate. This survey is a starting point for developing shared evidence-based immunization protocols for safe vaccination among pediatric transplant centers and generating new research studies.

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.

Vaccination Recommendations in Solid Organ Transplant Adult Candidates and Recipients

Prevention of infections is crucial in solid organ transplant (SOT) candidates and recipients. These patients are exposed to an increased infectious risk due to previous organ insufficiency and to pharmacologic immunosuppression. Besides infectious-related morbidity and mortality, this vulnerable group of patients is also exposed to the risk of acute decompensation and organ rejection or failure in the pre- and post-transplant period, respectively, since antimicrobial treatments are less effective than in the immunocompetent patients. Vaccination represents a major preventive measure against specific infectious risks in this population but as responses to vaccines are reduced, especially in the early post-transplant period or after treatment for rejection, an optimal vaccination status should be obtained prior to transplantation whenever possible. This review reports the currently available data on the indications and protocols of vaccination in SOT adult candidates and recipients.

A quick algorithmic review on management of viral infectious diseases in pediatric solid organ transplant recipients

Pediatric solid organ transplant is a life-saving procedure for children with end-stage organ failure. Viral infections are a common complication following pediatric solid organ transplantation (SOT), which can lead to increased morbidity and mortality. Pediatric solid organ transplant recipients are at an increased risk of viral infections due to their immunosuppressed state. The most commonly encountered viruses include cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV), varicella-zoster virus (VZV), adenoviruses, and BK polyomavirus. Prevention strategies include vaccination prior to transplantation, post-transplant prophylaxis with antiviral agents, and preemptive therapy. Treatment options vary depending on the virus and may include antiviral therapy and sometimes immunosuppression modification. This review provides a Quick Algorithmic overview of prevention and treatment strategies for viral infectious diseases in pediatric solid organ transplant recipient.

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.

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.

Post-transplant education for kidney recipients and their caregivers

Successful outcomes in pediatric kidney transplantation require the involvement of the transplant team as well as recipients and their caregivers. Enhancing patient and family understanding of the disease and of post-transplant care can result in improved adherence and outcomes. Educational strategies should aim to be broad, understandable, innovative, and inclusive while maintaining a tailored approach to individualized care. Teaching should not be viewed as a one-time event but rather as an ongoing conversation throughout the duration of care, emphasizing different aspects throughout the patient's various developmental stages. The following review article discusses the content and methods of post-transplant education.

Low post-transplant measles and varicella titers among pediatric liver transplant recipients: A 10-year single-center study

BACKGROUND

Vaccine preventable illnesses are important sources of morbidity, mortality, and increased healthcare costs in pediatric LT recipients. Our aim was to measure the seroprevalence of antibodies to measles and VZV in this population.

METHODS

We conducted a retrospective chart review of 44 patients who received LT before age 18 at UCLA Mattel Children's Hospital from January 2008 to December 2017.

RESULTS

Median age at transplantation was 2.5 years (IQR 1.2-7.7). Post-transplant measles antibodies were present in 17 of 37 patients (46%); risk factors for seronegativity included younger age at transplant (p = .02) and greater time from transplant to testing (p = .04). Post-transplant VZV antibodies were present in 17 of 39 patients (44%); risk factors for seronegativity included greater time from transplant to testing (p = .04). 6 of 16 patients (38%) who tested positive for pre-transplant VZV antibodies tested negative after transplantation. Fourteen of 20 patients (70%) with at least 1 documented dose of the MMR vaccine tested positive for post-transplant measles antibodies. Ten of 20 of patients (50%) with at least 1 documented dose of the VZV vaccine tested positive for post-transplant VZV antibodies. We also describe 10 patients who received post-transplant measles and VZV vaccines without documented complications.

CONCLUSIONS

Our study suggests that pediatric LT patients are at greater risk of contracting measles and VZV despite vaccination status, and that prevalence of measles and VZV antibodies decreases as time from transplantation increases. This should weigh into the institutional risk-benefit assessment when deciding whether or not to administer LAVs to these patients.

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.

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.

Prevention of viral infections in solid organ transplant recipients in the era of COVID-19: a narrative review

INTRODUCTION

In solid organ transplant (SOT) recipients, viral infections are associated with direct morbidity and mortality and may influence long-term allograft outcomes. Prevention of viral infections by vaccination, antiviral prophylaxis, and behavioral measures is therefore of paramount importance.

AREAS COVERED

We searched Pubmed to select publications to review current preventive strategies against the most important viral infections in SOT recipients, including SARS-CoV-2, influenza, CMV, and other herpesvirus, viral hepatitis, measles, mumps, rubella, and BK virus.

EXPERT OPINION

The clinical significance of the reduced humoral response following mRNA SARS-CoV-2 vaccines in SOT recipients still needs to be better clarified, in particular with regard to the vaccines' efficacy in preventing severe disease. Although a third dose improves immunogenicity and is already integrated into routine practice in several countries, further research is still needed to explore additional interventions. In the upcoming years, further data are expected to better delineate the role of virus-specific cell mediated immune monitoring for the prevention of CMV and potentially other viral diseases, and the role of the letermovir in the prevention of CMV in SOT recipients. Future studies including clinical endpoints will hopefully facilitate the integration of successful new influenza vaccination strategies into clinical practice.

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.

Lack of persisting antibody in a post-transplant patient after vaccine-strain varicella

BACKGROUND

LAVV have historically been avoided in children after solid organ transplantation. However, it has been reported that post-transplant, children without severe immunosuppression can generate anti-varicella antibody after immunization but the duration of the response is not clear. Furthermore, the origin of the varicella virus in immunosuppressed patients who develop varicella after vaccination is often unclear.

CLINICAL PROGRESS

A female child received LAVV 30 months after a living donor liver transplant at the age of 2 months. Varicella rash appeared on the trunk 16 days after vaccination and gradually spread over the body. The patient was treated with intravenous acyclovir followed by oral therapy and recovered fully. The virus detected in blisters was derived from the vaccine-type strain. Paired sera before and after the onset of varicella showed an increase in antibody titer. However, 2 years after onset, the antibody titer decreased to undetectable again.

CONCLUSIONS

This was an informative case of varicella due to vaccine strain attenuated virus. Antibody levels were not maintained over many years. Although varicella was caused by the vaccine-type strain, repeated vaccinations may be necessary for post-transplant patients who develop varicella.

Live Vaccines in Pediatric Liver Transplant Recipients: "To Give or Not to Give"

Content available: Author Audio Recording.

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.

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.

Optimizing virus protection in lung transplant recipients: Don't drop the ball

Meyer and Avery comment on the implications of a study by Hostetler et al. (page 2864), in which screening of a large group of lung transplant candidates revealed that some lacked humoral immunity to measles, mumps, and varicella, especially younger patients and those with cystic fibrosis.

Transplantation programs facing lack of empirical evidence on SARS-CoV-2 vaccination: A society recommendation consensus update

BACKGROUND

Since phase III trials for the most prominent vaccines excluded immunocompromised or immunosuppressed patients, data on safety and efficacy of SARS-CoV-2 vaccines for recipients of solid organ transplantations are scarce.

AIMS

Our study offers a synthesis of expert opinions aligned with available data addressing key questions of the clinical management of SARS-CoV-2 vaccinations for transplant patients.

METHOD

An online research was performed retrieving available recommendations by national and international transplantation organizations and state institutions on SARS-CoV2 vaccination management for transplant recipients.

RESULTS

Eleven key statements were identified from recommendations by 18 national and international societies, and consensus for the individual statements was evaluated by means of the Society Recommendation Consensus score. The highest consensus level (SRC A) was found for prioritized access to vaccination for transplant patients despite anticipation of a weakened immune response. All currently authorized vaccines can be considered safe for transplant patients (SRC A). The handling of immunosuppressive medication, the timely management of vaccines, and other aspects were aligned with available expert opinions.

CONCLUSION

Expert consensus can be determined for crucial aspects of the implementation of SARS-CoV-2 vaccination programs. We hereby offer a tool for immediate decision-making until empirical data becomes available.

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.

Recommendations for Vaccination in Children with Atopic Dermatitis Treated with Dupilumab: A Consensus Meeting, 2020

Dupilumab is the only biologic therapy currently approved in Europe and the United States for severe atopic dermatitis in patients 6 years of age or older. Off-label use is rationalized in younger children with severe atopic dermatitis. Decisions about vaccination for children on dupilumab are complex and depend on both the child's current treatment and the type of vaccination required. To achieve consensus on recommendations for vaccination of pediatric patients with atopic dermatitis treated with or planning to start dupilumab, a review of the literature and a modified-Delphi process was conducted by a working group of 5 panelists with expertise in dermatology, immunology, infectious diseases and vaccination. Here, we provide seven recommendations for vaccination of pediatric patients with atopic dermatitis treated with or planning to start dupilumab. These recommendations serve to guide physicians' decisions about vaccination in children with atopic dermatitis treated with dupilumab. Furthermore, we highlight an unmet need for research to determine how significantly dupilumab affects cellular and humoral immune responses to vaccination with live attenuated and inactivated vaccines.

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.

Live attenuated vaccines under immunosuppressive agents or biological agents: survey and clinical data from Japan

Live attenuated vaccines are contraindicated for patients on immunosuppressive agents or biological agent, except for live attenuated varicella vaccine, although previous reports showed their effectiveness and safety. This study is the nationwide cross-sectional research about the current utilization of live attenuated vaccines for patients on immunosuppressive agents or biological agents in Japan. We sent questionnaires to pediatric centers and examined whether each institution offered live attenuated vaccines to patients with immunosuppressive agents or biological agents (institutional research). We also examined adverse events associated with live attenuated vaccines between 2013 and 2017 (patient research). In the institutional research, 46 out of 334 institutions (13.8%) administered live attenuated vaccines to patients receiving immunosuppressive agents. In contrast, only six out of 270 institutions (2.2%) administered live attenuated vaccines to patients receiving biological agents. However, 66.3% of physicians answered that patients receiving immunosuppressive agents should be immunized with live attenuated vaccines, and only 7.0% disagreed with them. In the patient research, data for 781 patients were collected. Vaccine-associated infections were observed in only two patients (0.3%), both of whom had varicella, although they recovered promptly. No life-threatening adverse events were noted.

CONCLUSION

In pediatric centers, the demand for live attenuated vaccines in patients receiving immunosuppressive agents was high and most physicians think they should be immunized. Immunization with live attenuated vaccines appeared safe in patients receiving immunosuppressive agents, although further studies are needed for patients receiving biological agents What is known: • Live attenuated vaccines (LAV) are generally contraindicated for patients on immunosuppressive agents (IS) or biological agents (BA), except for live attenuated varicella vaccine, as immunocompromised patients are at greater risk for serious viral infection from the vaccine strains. • Viral infections, such as measles and varicella, cause serious complications in children receiving IS. • Several previous reports showed that LAV is relatively effective and safe for patients receiving IS. What is new: • In Japan, the demand for LAV in patients receiving IS was high, and most physicians hoped they should be immunized. • Vaccine-associated infection is rarely observed in patients with IS after LAV administration. • Immunization with LAV appeared safe in patients receiving IS.

TRIAL REGISTRATION

University Hospital Medical Information Network (UMIN).

TRIAL REGISTRATION NUMBER

UMIN000029176.Date of registration: 2017/09/19.

Safety and efficacy of early vaccination with live attenuated measles vaccine for hematopoietic stem cell transplant recipients and solid organ transplant recipients

BACKGROUND AND OBJECTIVE

Vaccination with the live attenuated measles vaccine is currently recommended two years after hematopoietic stem cell transplantation (HSCT) and generally contraindicated after solid organ transplantation (SOT) due to safety concerns. However, in the last few years new data on the administration of the measles vaccine to HSCT recipients less two years post-transplantation and to SOT recipients have become available. This new data may change current guidelines and practices. The objective of this review is to provide an overview of the current data on the safety and efficacy of early measles vaccination for HSCT- and SOT recipients.

METHOD

PubMed and EMBASE were searched from the earliest date available through October 2019 to identify all research that reported on the safety and efficacy of measles vaccination after SOT or less than two years after HSCT.

RESULTS

A total of ten studies was included in this review. In the six studies that evaluated the efficacy of measles vaccination after SOT, seroconversion rates ranged from 41 to 100% after one dose and 73 to 100% after two doses. In the four studies that evaluated the efficacy of measles vaccination less than two years after HSCT, seroconversion rates ranged from 33 to 100% after one dose and 100% after two doses. In all studies, the administration of the measles vaccine after transplantation was considered to be safe. There were no cases of infection with the attenuated vaccine strain, and there were no adverse events related to the vaccination.

CONCLUSION

Data on the administration of the measles vaccine after SOT and less than two years after HSCT is scarce. However, the current data available suggest that it is efficacious and well tolerable. Therefore, early measles vaccination could be considered in selected groups of SOT- and HSCT recipients during increased measles transmission or an outbreak setting.

Principles of immunisation in children with solid organ transplant

Vaccine-preventable diseases (VPD) are a significant risk to paediatric solid organ transplant (SOT) recipients on lifelong immunosuppressive therapy. Children progressing to end-stage organ dysfunction are unable to mount a robust immune response. Hence, it is important to plan vaccination early in the course of disease, especially if a child is anticipated to be a SOT candidate. Vaccine recommendations need to be individualised in this population based on vaccine history and serology. Catch-up or accelerated schedules may be used to complete vaccinations before transplant. Post-transplant, immunisation is recommenced in consultation with the transplant team taking into context the time since transplant and the intensity of the immunosuppressive regime. Inactivated vaccines are safe post-transplant but postexposure prophylaxis may still be required in children with inadequate immunity to VPD. Specific vaccines may be advised for SOT recipients travelling abroad (in consultation with a travel clinic) or those entering high-risk professions. Additionally, the vaccination status of all household members and close contacts should be reviewed and optimised, offering additional protection to the transplant recipient.

Evaluation of Recombinant Herpes Zoster Vaccine for Primary Immunization of Varicella-seronegative Transplant Recipients

BACKGROUND

Immunization of VZV-seronegative solid organ transplant (SOT) patients using the live-attenuated varicella vaccine is generally contraindicated, leaving no widely applicable immunization option. The recombinant subunit herpes zoster vaccine (RZV) is indicated for VZV seropositive persons to prevent shingles but could potentially also protect VZV-seronegative persons against varicella. We performed a safety and immunogenicity evaluation of RZV in VZV-seronegative SOT recipients as an option for protection.

METHODS

VZV-seronegative adult SOT patients with no history of varicella/shingles vaccine or disease were given 2 doses of RZV vaccine 2-6 months apart. Blood was drawn prevaccination (V1), prior to the second dose (V2) and 4 weeks after second dose (V3). Humoral (anti-gE) and cell-mediated immunity was evaluated, with polyfunctional cells defined as cells producing ≥2 cytokines.

RESULTS

Among 31 eligible VZV-seronegative SOT patients screened, 23 were enrolled. Median age was 38 years and median time since transplant procedure was 38 years. The most frequent transplant types were liver (35%) and lung (30%). Median anti-gE levels significantly increased from V1 to V3 (p=0001) and V2 to V3 (p<0001), even though only 55% had a positive seroresponse. Median polyfunctional CD4 T-cells counts increased from V1 to V2 (54/10 vs 104/10 cells; p=0041), and from V2 to V3 (380/10; p=0002). Most adverse events were mild with no rejection episodes.

CONCLUSION

RZV was safe and elicited significant humoral and cellular responses in VZV-seronegative SOT patients, and has the potential to be considered as a preventive strategy against primary varicella.

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.

Measles outbreak risk assessment for transplant candidates and recipients

Solid organ transplant (SOT) candidates and recipients are at risk of significant morbidity and mortality from infection, including those circulating in the community from unexpected outbreaks. In late 2018-summer of 2019, a measles outbreak occurred in the New York City area, with a total of 649 cases reported. We developed a systematic 3-part approach to address measles risk in our adult SOT program through: (a) identification of nonimmune adults living in outbreak ZIP codes, (b) education focused on risk reduction for patients from outbreak ZIP codes, and (c) risk reduction for nonimmune patients. All waitlisted or previously transplanted patients residing in outbreak areas received a measles patient education handout. The electronic medical record of patients born in or after 1957 was reviewed for serologic evidence of measles immunity. Measles immunity testing was performed in patients without documentation of immunity. Patients who tested nonimmune were offered MMR vaccination or intravenous immunoglobulin depending on their transplant phase and risk profile. Thus, we demonstrate successful implementation of a systematic risk assessment during a large measles outbreak to identify and protect at-risk SOT patients. As vaccine hesitancy persists, our strategies may be increasingly relevant to transplant centers and those caring for immunocompromised patients.

A community divided: Post-transplant live vaccine practices among Society of Pediatric Liver Transplantation (SPLIT) centers

BACKGROUND

Historically, the IDSA and the AST have recommended that live vaccines not be administered post-transplant due to concern for induction of vaccine-strain disease in immunocompromised hosts. However, recent prospective studies and revised AST guidelines published in April 2019 suggest that in the current era of immunosuppression minimization, live vaccines may be safely administered to select transplant recipients with resulting immunoprotection. The goal of this study was to assess current post-transplant live vaccine practices at individual pediatric liver transplant centers following the updated AST guidelines.

METHODS

A six-item email survey detailing center-specific post-transplant live vaccine practices followed by up to three response-specific questions were distributed between July 2019 and May 2020 to a representative from each center participating in the SPLIT consortium.

RESULTS

The overall survey response rate was 93% (41/44 centers). Only 29% (12/41) of centers offer live vaccines post-transplant; each of these 12 centers uses different eligibility criteria for live vaccines. There was no difference between large (ten or more transplants per year) and small (less than ten transplants per year) centers in likelihood to offer live vaccines post-transplant. The main reasons for a center not offering post-transplant live vaccines were safety concerns and inability to reach group consensus.

CONCLUSIONS

The majority of pediatric liver transplant centers are reluctant to offer live vaccines post-transplant despite the updated AST guidelines. Prospective multicenter studies are needed to confirm safety and immunogenicity of live vaccines post-transplant.

Varicella infection following vaccination in a pediatric kidney transplant recipient

Live viral vaccines have historically been avoided in children after solid organ transplantation. Multiple reports of safety and immunogenicity, largely in the pediatric liver transplant population, have led to a reconsideration of this recommendation. Here, we report the case of a 4-year-old boy who inadvertently received the live attenuated MMR-varicella vaccine (MMRV) at a routine well-child visit 16 months after receiving a living donor kidney transplant. This was not known until after he was admitted with rash and documented disseminated varicella infection 5 weeks later. He was treated with intravenous acyclovir followed by oral therapy and recovered fully. This case and its discussion illustrate what is still unknown about the risk-to-benefit ratio of live viral vaccination in any individual transplant recipient. Criteria to determine which patients should receive these vaccines should be evaluated before their use after transplant becomes routine, and all recipients and their families should be counseled to have a low threshold to seek medical care for any febrile illness or rash after live viral vaccination.

Missed vaccinations and critical care admission: all you may wish to know or rediscover-a narrative review

Most vaccines are so effective that they could lead to the control/elimination of the diseases they target and directly impact on intensive care admissions or complications. This is best illustrated by the use of vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae, zoster, yellow fever, Ebola virus, influenza or measles-but also by third party strategies such as maternal, toddler and care-giver immunization. However, each of these vaccine-induced protection is threatened by insufficient vaccine uptake. Here, we briefly discuss how vaccine hesitancy has led to the resurgence of diseases that were considered as controlled and explore the effect of vaccine-hesitant healthcare workers on nosocomial infections. As intensive care physicians are in charge of polymorbid patients, we briefly summarize the current recommendations for vaccinations in high-risk patients. We finally give some perspective on ongoing research, and discuss how institutional policies and intensive care physicians could play a role in increasing the impact of vaccination, overall and in intensive care units.