Updated data on effective and safe immunizations with live-attenuated vaccines for children after living donor liver transplantation. Vaccine. 2015;33:701-707. [PMID: 25510391 DOI: 10.1016/j.vaccine.2014.11.052]

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.

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.

Assessing clinical benefits of live-attenuated vaccination in post-liver transplant patients: Analysis of breakthrough infections and natural boosters

Recently, live-attenuated measles, rubella, varicella, and mumps vaccines have been administered to carefully selected post-liver transplant patients. Although attention has been focused on post-vaccination antibody titers and adverse events, the real-life clinical benefits remain unclear. A comprehensive analysis of breakthrough infections and natural boosters (asymptomatic cases with significant elevation in virus antibody titers) following immunization post-liver transplantation was conducted from 2002-2023, exploring the timing, frequency, correlation with domestic outbreaks, and degree of antibody elevation. During the median 10-year observation period among 68 post-liver transplant patients, breakthrough infections occurred only in chickenpox, with 7 mild cases (1 episode/64 person-years). A total of 59 natural booster episodes (1, 5, 20, and 33 for measles, rubella, chickenpox, and mumps, respectively) were observed, with incidence rates of 1 per 569, 110, 22, and 17 person-years, respectively. The timing of natural boosters closely correlated with domestic outbreaks (P < .05 in chickenpox and mumps), influenced by local vaccine coverage. The degree of antibody elevation was significantly higher in individuals with breakthrough infections than in those with natural boosters (P < .05). These findings suggest that immunization with live-attenuated vaccines for post-liver transplant patients has demonstrated clinical benefits. Furthermore, mass vaccination has a positive impact on post-transplant patient outcomes.

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.

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.

Safety and Immunogenicity of Live Viral Vaccines in a Multicenter Cohort of Pediatric Transplant Recipients

Importance

Live vaccines (measles-mumps-rubella [MMR] and varicella-zoster virus [VZV]) have not been recommended after solid organ transplant due to concern for inciting vaccine strain infection in an immunocompromised host. However, the rates of measles, mumps, and varicella are rising nationally and internationally, leaving susceptible immunocompromised children at risk for life-threating conditions.

Objective

To determine the safety and immunogenicity of live vaccines in pediatric liver and kidney transplant recipients.

Design, Setting, and Participants

This cohort study included select pediatric liver and kidney transplant recipients who had not completed their primary MMR and VZV vaccine series and/or who displayed nonprotective serum antibody levels at enrollment between January 1, 2002, and February 28, 2023. Eligibility for live vaccine was determined by individual US pediatric solid organ transplant center protocols.

Exposures

Exposure was defined as receipt of a posttransplant live vaccine. Transplant recipients received 1 to 3 doses of MMR vaccine and/or 1 to 3 doses of VZV vaccine.

Main Outcome and Measure

Safety data were collected following each vaccination, and antibody levels were obtained at 0 to 3 months and 1 year following vaccination. Comparisons were performed using Mann-Whitney U test, and factors associated with development of postvaccination protective antibodies were explored using univariate analysis.

Results

The cohort included 281 children (270 [96%] liver, 9 [3%] kidney, 2 [1%] liver-kidney recipients) from 18 centers. The median time from transplant to enrollment was 6.3 years (IQR, 3.4-11.1 years). The median age at first posttransplant vaccine was 8.9 years (IQR, 4.7-13.8 years). A total of 202 of 275 (73%) children were receiving low-level monotherapy immunosuppression at the time of vaccination. The majority of children developed protective antibodies following vaccination (107 of 149 [72%] varicella, 130 of 152 [86%] measles, 100 of 120 [83%] mumps, and 124 of 125 [99%] rubella). One year post vaccination, the majority of children who initially mounted protective antibodies maintained this protection (34 of 44 [77%] varicella, 45 of 49 [92%] measles, 35 of 42 [83%] mumps, 51 of 54 [94%] rubella). Five children developed clinical varicella, all of which resolved within 1 week. There were no cases of measles or rubella and no episodes of graft rejection within 1 month of vaccination. There was no association between antibody response and immunosuppression level at the time of vaccination.

Conclusions and Relevance

The findings suggest that live vaccinations may be safe and immunogenic after solid organ transplant in select pediatric recipients and can offer protection against circulating measles, mumps, and varicella.

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.

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.

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.

Safety of LAVs administered after pediatric LT

Recent guidelines suggest that LAVs may be given to LT recipients meeting certain criteria. However, information is still limited. We sought to evaluate the safety of LAVs, including measles, mumps, rubella, and varicella to LT recipients following our clinically based immunization protocol for LT recipients. We conducted a case-series analysis on safety of LAVs for measles, rubella, varicella, and mumps given to LT recipients at our institution from July 2010 to July 2019. Patients who underwent LT at age <20 years who visited our immunization clinic were included. LT recipients were vaccinated if 2 years had lapsed from LT, had no signs of rejection within 6 months, and were on minimal immunosuppressants. Patient demographics, underlying diseases, type and number of vaccines administered, date of vaccination, and adverse events occurring within 4 weeks after vaccination were extracted from their medical records. During the study period, LAVs were administered 422 times to 209 patients who met criteria and included 225 doses of MR combination vaccine, 224 doses of varicella vaccine, and 215 doses of mumps vaccine. Underlying diseases included cholestatic liver diseases (n = 125), followed by metabolic diseases (n = 33) and acute liver failure (n = 19). Nine non-critical adverse events (2.1%) possibly associated with LAVs were reported, but there were no serious adverse events, including hospitalizations or deaths. In conclusion, LAVs administered to LT recipients were safe without any serious adverse events following our relatively simple institutional protocol.

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.

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.

Management and prevention of varicella and measles infections in pediatric solid organ transplant candidates and recipients: An IPTA survey of current practice

BACKGROUND

Varicella and measles infections can be life-threatening after solid organ transplantation (SOT) but may be preventable with live-attenuated vaccines (LAV).

METHODS

This survey conducted in January 2019 among subscribers of the International Pediatric Transplantation Association listserv aimed to explore the current strategies to prevent and manage both infections in the pediatric SOT population, including recommending LAV after SOT.

RESULTS

The answers given by 95 pediatric SOT healthcare workers show that these strategies are not yet optimal and call for further education. In particular, 59% of respondents are unnecessarily waiting for a SOT candidate to be >1 year of age to start administrating LAV before SOT. Interestingly, most respondents are willing to administer LAV after SOT (57%), and a fifth (21%) are already doing so, off-label. The survey queried the precautions taken to improve safety evaluations after LAV, and identified knowledge gaps and practitioners' concerns.

CONCLUSION

The results of this survey could be used as a starting point for education and promotion of the safe administration of LAV in carefully selected SOT recipients; in turn, this would increase available data that would contribute to the development of evidence-based guidelines by the transplant societies and ultimately prevent these infections after SOT.

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.

Vaccine-associated measles in a patient treated with natalizumab: a case report

Background

Safety of live vaccines in patients treated with immunosuppressive therapies is not well known, resulting in contradictory vaccination recommendations. We describe here the first case of vaccine-associated measles in a patient on natalizumab treatment.

Case presentation

A young female patient with relapsing-remitting multiple sclerosis on natalizumab treatment received the live attenuated measles, mumps, and rubella vaccine in preparation for a change in her treatment in favour of fingolimod, with established immunosuppressive qualities. Seven days after receiving the vaccine, our patient experienced diffuse muscle pain, fatigue, and thereafter developed a fever and then an erythematous maculopapular rash, compatible with vaccine associated measles. This was later confirmed by a positive measles RT-PCR throat swab. The patient’s symptoms resolved without any sequelae.

Conclusion

In this case report we review the immunosuppressive qualities of natalizumab and the evidence in favour and against live vaccines in patients on this treatment. Our findings reveal the insufficient understanding of the immunosuppressive effects of new immunomodulators, and thus of the safety of live vaccines in patients on such medications. While this case triggers precaution, there is insufficient evidence to conclude that natalizumab treatment could favor the onset of vaccine-associated measles.

Prospective study of live attenuated vaccines for patients receiving immunosuppressive agents

Patients receiving immunosuppressive agents are at risk of life-threatening infections. However, live vaccines are generally contraindicated in them. We conducted a prospective study regarding live attenuated vaccines for them. Patients elder than one year of age with immunosuppressive agents who showed negative or borderline antibody titers (virus-specific IgG levels < 4.0) against one or more of measles, rubella, varicella, and mumps and fulfilled the criteria (CD4 cell counts ≥ 500/mm3, stimulation index of lymphocyte blast transformation by PHA ≥ 101.6, serum IgG level ≥ 300 mg/dl, no steroid use or prednisolone < 1 mg/kg/day or < 2 mg/kg/2 days, trough levels of tacrolimus or cyclosporine were < 10 ng/ml or < 100 ng/ml and under good control of primary disease) were enrolled. Sixty-four vaccinations were administered to 32 patients. The seroconversion rates for measles, rubella, varicella, and mumps were 80.0%, 100.0%, 59.1%, and 69.2%, respectively. No life-threatening adverse events were observed, although one patient suffered from vaccine-strain varicella who showed cellular and humoral immunodeficiency (CD4 cell counts = 511/mm3, stimulation index of lymphocyte blast transformation by PHA = 91.1, serum IgG level = 208 mg/dl). This girl was immunized before we established the criteria for vaccination. Immunization with live attenuated vaccines for patients receiving immunosuppressive agents might be effective and safe if their cellular and humoral immunological parameters are within normal levels. However, determining the criteria for vaccination by immunological parameters should be established to guarantee the safety of live vaccines in the future. Clinical Trial Registration: UMIN Clinical Trials Registry (UMIN-CTR) UMIN000007710. The date of registration: 2012/4/13.

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

Growing evidence suggests receipt of live-attenuated viral vaccines after solid organ transplant (SOT) has occurred and is safe and needed due to lapses in herd immunity. A 2-day consortium of experts in infectious diseases, transplantation, vaccinology, and immunology was held with the objective to review evidence and create expert recommendations for clinicians when considering live viral vaccines post-SOT. For consideration of VV and MMR post-transplant, evidence exists only for kidney and liver transplant recipients. For MMR vaccine post-SOT, consider vaccination during outbreak or travel to endemic risk areas. Patients who have received antiproliferative agents (eg. mycophenolate mofetil), T cell-depleting agents, or rituximab; or have persistently elevated EBV viral loads, or are in a state of functional tolerance, should be vaccinated with caution and have a more in-depth evaluation to define benefit of vaccination and net state of immune suppression prior to considering vaccination. MMR and/or VV (not combined MMRV) is considered to be safe in patients who are clinically well, are greater than 1 year after liver or kidney transplant and 2 months after acute rejection episode, can be closely monitored, and meet specific criteria of "low-level" immune suppression as defined in the document.

Vaccinations in pediatric kidney transplant recipients

Pediatric kidney transplant (KT) candidates should be fully immunized according to routine childhood schedules using age-appropriate guidelines. Unfortunately, vaccination rates in KT candidates remain suboptimal. With the exception of influenza vaccine, vaccination after transplantation should be delayed 3-6 months to maximize immunogenicity. While most vaccinations in the KT recipient are administered by primary care physicians, there are specific schedule alterations in the cases of influenza, hepatitis B, pneumococcal, and meningococcal vaccinations; consequently, these vaccines are usually administered by transplant physicians. This article will focus on those deviations from the normal vaccine schedule important in the care of pediatric KT recipients. The article will also review human papillomavirus vaccine due to its special importance in cancer prevention. Live vaccines are generally contraindicated in KT recipients. However, we present a brief review of live vaccines in organ transplant recipients, as there is evidence that certain live virus vaccines may be safe and effective in select groups. Lastly, we review vaccination of pediatric KT recipients prior to international travel.

Multimodal safety assessment of measles-mumps-rubella vaccination after pediatric liver transplantation

Live-attenuated vaccines are currently contraindicated in solid-organ transplant recipients. However, the risk of vaccine-preventable infections is lifelong, and can be particularly severe after transplantation. In this prospective interventional national cohort study, 44 pediatric liver transplant recipients with measles IgG antibodies <150 IU/L (below seroprotection threshold) received measles-mumps-rubella vaccine (MMR) at a median of 6.3 years posttransplantation (interquartile range, 4.0 to 10.9). A maximum of two additional doses were administered in nonresponders or when seroprotection was lost. Vaccine responses occurred in 98% (95% confidence interval [CI], 88-100) of patients. Seroprotection at 1-, 2-, and 3-year follow-up reached 62% (95% CI, 45-78), 86% (95% CI, 70-95), and 89% (95% CI, 67-99), respectively. All patients responded appropriately to the booster dose(s). Vaccinations were well tolerated and no serious adverse event attributable to vaccination was identified during the 8-week follow-up period (or later), using a multimodal approach including standardized telephone interviews, diarized side effect reporting, and monitoring of vaccinal virus shedding. We conclude that live attenuated MMR vaccine can be administered in liver transplant recipients fulfilling specific eligibility criteria (>1 year posttransplantation, low immunosuppression, lymphocyte count ≥0.75 G/L), inducing seroprotection in most subjects. (Clinicaltrials.gov number NCT01770119).

Vaccines in pediatric transplant recipients-Past, present, and future

Infections significantly impact outcomes for solid organ and hematopoietic stem cell transplantation in children. Vaccine-preventable diseases contribute to morbidity and mortality in both early and late posttransplant time periods. Several infectious diseases and transplantation societies have published recommendations and guidelines that address immunization in adult and pediatric transplant recipients. In many cases, pediatric-specific studies are limited in size or quality, leading to recommendations being based on adult data or mixed adult-pediatric studies. We therefore review the current state of evidence for selected immunizations in pediatric transplant recipients and highlight areas for future investigation. Specific attention is given to studies that enrolled only children.

Prospective Study of Live Attenuated Vaccines for Patients with Nephrotic Syndrome Receiving Immunosuppressive Agents

OBJECTIVE

To conduct a prospective study to evaluate the immunogenicity and safety of live attenuated vaccines in patients with nephrotic syndrome receiving immunosuppressive agents.

STUDY DESIGN

Patients with nephrotic syndrome receiving immunosuppressive agents with negative or borderline antibody titers (virus-specific IgG levels <4.0) against measles, rubella, varicella, and/or mumps fulfilling the criteria of cellular and humoral immunity were enrolled. Virus-specific IgG levels were measured using an enzyme immunoassay. The primary endpoint was the seroconversion rate (ie, achievement of virus-specific IgG levels ≥4.0) at 2 months after vaccination. Virus-specific IgG levels at 1 year, breakthrough infections (wild-type infections), and adverse events were also evaluated.

RESULTS

A total of 116 vaccinations were administered to 60 patients. Seroconversion rates were 95.7% for measles, 100% for rubella, 61.9% for varicella, and 40.0% for mumps. More patients with a borderline antibody titer before vaccination achieved seroconversion than those with negative antibody titer, with statistical significance after varicella and mumps vaccination. The rate of patients who maintained seropositivity at 1 year after vaccination was 83.3% for measles, 94.1% for rubella, 76.7% for varicella, and 20.0% for mumps. No patient experienced breakthrough infection. No serious adverse events, including vaccine-associated infection, were observed.

CONCLUSION

Immunization with live attenuated vaccines may be immunogenic and is apparently safe in our cohort of patients with nephrotic syndrome receiving immunosuppressive agents if their cellular and humoral immunologic measures are within clinically acceptable levels.

TRIAL REGISTRATION

UMIN-CTR UMIN 000007710.

Safety of live vaccines on immunosuppressive or immunomodulatory therapy-a retrospective study in three Swiss Travel Clinics

BACKGROUND

Patients increasingly benefit from immunosuppressive/immunomodulatory medications for a range of conditions allowing them a lifestyle similar to healthy individuals, including travel. However, the administration of live vaccines to immunodeficient patients bears the risk of replication of the attenuated vaccine microorganism. Therefore, live vaccines are generally contraindicated on immunosuppression. Data on live vaccinations on immunosuppressive/immunomodulatory medication are scarce. We identified all travellers seeking pre-travel advice in three Swiss travel clinics with a live vaccine during immunosuppressive/immunomodulatory therapy to ascertain experienced side effects. A retrospective and multi-centre study design was chosen to increase the sample size.

METHODS

This study was conducted in the travel clinics of the University of Zurich; the Swiss TPH, Basel; and Geneva University Hospitals. Travellers on immunosuppressive/immunomodulatory therapy who received live vaccines [yellow fever vaccination (YFV), measles/mumps/rubella (MMR), varicella and/ or oral typhoid vaccination (OTV)] between 2008 and 2015 were identified and interviewed. A total of 60 age- and sex-matched controls (matched to Basel/Zurich travel clinics travellers) were included.

RESULTS

Overall, 197 patients were identified. And 116 patients (59%) and 60 controls were interviewed. YFV was administered 92 times, MMR 21 times, varicella 4 times and OTV 6 times to patients on immunosuppressive/immunomodulatory therapy. Most common medications were corticosteroids (n = 45), mesalazine (n = 28) and methotrexate (n = 19). Live vaccines were also administered on biological treatment, e.g. TNF-alpha inhibitors (n = 8). Systemic reactions were observed in 12.2% of the immunosuppressed vs 13.3% of controls; local reactions in 7.8% of the immunosuppressed vs 11.7% of controls. In controls, all reactions were mild/moderate. In the immunosuppressed, 2/21 severe reactions occurred: severe local pain on interferon-beta and severe muscle/joint pain on sulfasalazine.

CONCLUSION

Safety of live vaccines given to immunosuppressed patients cannot be concluded. However, it is re-assuring that in the examined patient groups no serious side effects or infections by the attenuated vaccine strain occurred.

Measles hepatitis in a vaccinated liver transplant recipient: case report and review of literature

Measles infection, postliver transplant, may lead to a fatal graft loss. Individuals who have been previously exposed to the measles antigen may have a modified disease presentation. Although vaccination may not provide solid immunity, it ameliorates the severity of the disease.

Serostatus following live attenuated vaccination administered before pediatric liver transplantation

After liver transplantation (LT), live attenuated vaccines (LAVs) are generally contraindicated. LAVs are recommended before LT for patients ≥ 6 months of age. However, the evidence supporting this practice is limited. Patients were enrolled before and after LT. Clinical data for patients were obtained from medical records. Serum antibody titers were evaluated at the time of enrollment and prospectively. Serum antibody titers were measured with a hemagglutination inhibition test for measles and rubella and with an enzyme-linked immunosorbent assay for varicella and mumps. Univariate and multivariate analyses were performed to investigate the factors that affect the serostatus. Serological analyses of 49 patients immunized before LT (median age, 45 months; male, 35%) were performed. Underlying diseases were biliary atresia (n = 27; 55%), metabolic diseases (n = 13; 27%), fulminant hepatic failure (n = 5; 10%), and others (n = 4; 8%). The seropositivity rate after each vaccine was 46.9% (measles), 89.4% (rubella), 67.5% (varicella), and 48.8% (mumps). Factors independently associated with seronegativity were a vaccination age < 12 months for measles (P = .002), a lower body weight for varicella (P = 0.01), and underlying diseases other than biliary atresia for mumps (P = .004). No serious adverse event was observed during the study period. The immunogenicity of LAVs before LT was high for rubella but low for the others. Before LT, further vaccination strategies are needed for patients. In addition, serological follow-up may be indicated for patients with factors associated with seronegativity.