An update on immunizations before and after transplantation in the pediatric solid organ transplant recipient

Serological responses to immunization during nephrosis in infants with congenital nephrotic syndrome of the Finnish type

Background

Pretransplant vaccination is generally recommended to solid organ transplant recipients. In infants with congenital nephrotic syndrome (CNS), the immune response is hypothetically inferior to other patients due to young age and urinary loss of immunoglobulins, but data on the immunization response in severely nephrotic children remain scarce. If effective, however, early immunization of infants with CNS would clinically be advantageous.

Methods

We investigated serological vaccine responses in seven children with CNS who were immunized during nephrosis. Antibody responses to measles-mumps-rubella -vaccine (MMR), a pentavalent DTaP-IPV-Hib -vaccine (diphtheria, tetanus, acellular pertussis, inactivated poliovirus, Haemophilus influenzae type b), varicella vaccine, combined hepatitis A and B vaccine, and pneumococcal conjugate vaccine (PCV) were measured after nephrectomy either before or after kidney transplantation.

Results

Immunizations were started at a median age of 7 months [interquartile range (IQR) 7-8], with a concurrent median proteinuria of 36,500 mg/L (IQR 30,900-64,250). Bilateral nephrectomy was performed at a median age of 20 months (IQR 14-25), and kidney transplantation 10-88 days after the nephrectomy. Antibody levels were measured at median 18 months (IQR 6-23) after immunization. Protective antibody levels were detected in all examined children for hepatitis B (5/5), Clostridium tetani (7/7), rubella virus (2/2), and mumps virus (1/1); in 5/6 children for varicella; in 4/6 for poliovirus and vaccine-type pneumococcal serotypes; in 4/7 for Haemophilus influenzae type B and Corynebacterium diphtheriae; in 1/2 for measles virus; and in 2/5 for hepatitis A. None of the seven children had protective IgG levels against Bordetella pertussis.

Conclusion

Immunization during severe congenital proteinuria resulted in variable serological responses, with both vaccine- and patient-related differences. Nephrosis appears not to be a barrier to successful immunization.

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

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

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.

Heart Disease in Children

The pediatric cardiology field has developed rapidly over the past few decades. More children than ever born with congenital heart disease (CHD) are growing into adulthood. Primary care providers play a key role in diagnosis, management, and referral of children with CHD because many common cardiac complaints (eg, feeding intolerance, cyanosis, chest pain, palpitations, and syncope) are first addressed in the primary care setting. The spectrum of heart disease in children ranges from common complaints to complex single-ventricle physiology, acute myocarditis, and heart transplantation. This article reviews the pathophysiology and management of the most frequent cardiac conditions encountered in primary care.

Cochlear implantation of solid organ transplant patients receiving immunosuppressive therapy

OBJECTIVE

To evaluate the incidence of infectious complications and healing problems in cochlear implant (CI) patients receiving immunosuppressive therapy following solid organ transplant.

STUDY DESIGN

IRB-approved retrospective chart review of implanted patients.

SETTING

Tertiary care children's hospital.

METHODS

Seven patients of the more than 1000 implanted during the time period between 1991 and 2014 underwent cochlear implantation while on immunosuppressive therapy after having received a solid organ transplant. Their charts were reviewed for demographic and medical information pre- and post-implantation. The 4 males and 3 females ranged in age at CI from 2.4 to 18.8 years, with a mean of 9.0 years. Postimplant follow-up averaged 3.9 years (range: 0.1-13.1). Main outcome measures were occurrence of wound healing, infectious complications, whether open-set word recognition was achieved, and communication mode(s).

RESULTS

No wound infections or delayed healing, mastoiditis, or bacterial meningitis occurred after cochlear implantation. All seven patients had received at least one pneumococcal vaccination prior to implantation. Five of 6 (83%) developed open-set speech perception, of whom 4 (67%) use only oral communication.

CONCLUSION

In our series of patients receiving immunosuppressive therapy following solid organ transplantation, none developed wound healing or infectious complications after cochlear implantation. History of solid organ transplantation alone should not be a contraindication to cochlear implant candidacy which would deprive the child of the potential benefits of hearing, including language development.

Waning of vaccine-induced immunity to measles in kidney transplanted children

Vaccine-preventable diseases are a significant cause of morbidity and mortality in solid organ transplant recipients who undergo immunosuppression after transplantation. Data on immune responses and long-term maintenance after vaccinations in such population are still limited.We cross-sectionally evaluated the maintenance of immune response to measles vaccine in kidney transplanted children on immunosuppressive therapy. Measles-specific enzyme-linked immunosorbent assay and B-cell enzyme-linked immunosorbent spot were performed in 74 kidney transplant patients (Tps) and in 23 healthy controls (HCs) previously vaccinated and tested for humoral protection against measles. The quality of measles antibody response was measured by avidity test. B-cell phenotype, investigated via flow cytometry, was further correlated to the ability of Tps to maintain protective humoral responses to measles over time.We observed the loss of vaccine-induced immunity against measles in 19% of Tps. Nonseroprotected children showed signs of impaired B-cell distribution as well as immune senescence and lower antibody avidity. We further reported as time elapsed between vaccination and transplantation, as well as the vaccine administration during dialysis are clinical factors affecting the maintenance of the immune memory response against measles.Tps present both quantitative and qualitative alterations in the maintenance of protective immunity to measles vaccine. Prospective studies are needed to optimize the vaccination schedules in kidney transplant recipients in order to increase the immunization coverage over time in this population.

Vaccinations, response, and controls before and after intestinal transplantation in children

Vaccination is an effective strategy to decrease infections in transplant recipients. Children after intestinal transplantation carry a high risk of infection due to increased immunosuppression. In a series of 22 children after intestinal transplantation, we studied the vaccination schedules and the antibodies against vaccine-preventable diseases before transplantation, and at one and five yr after transplantation. We reviewed whether the vaccination schedules were complete, and we analysed the factors that may influence serological immunity and the incidence of disease in patients with deficient immunity. All patients completed the recommended vaccination schedules for DTaP-IPV and HBV. After transplantation, the negative antibodies against vaccine-preventable diseases were mostly related to an antirejection therapy: for DTaP-IPV: four of four patients with no antibody had been treated for rejection, for HBV: two of five, HAV: three of four, MMR: three of seven, and VZV: three of four. A post-transplantation varicella infection was followed by acute rejection, with probability for a relationship between both events. We observed 50% of varicella cases in unvaccinated children, highlighting the importance of pretransplant vaccination. Waning immunogenicity mediated by antibodies against vaccine-preventable disease after transplantation indicated a need for boosters. The recommendations should be regularly enforced, as the reliance on routine immunizations schedules is not adequate in immunocompromised patients.

Immunization in transplantation: review of the recent literature

PURPOSE OF REVIEW

Immunosuppressive treatments increase the life-long risk of solid organ transplant (SOT) recipients for severe infections, some of which are vaccine-preventable. In this review of the literature published during the last 15 months, we critically summarize vaccine-oriented articles in SOT candidates or recipients. Because of previously reported differences, vaccine-specific studies are needed for each type of SOT recipients.

RECENT FINDINGS

Thanks to new data gathered during the H1N1/2009 influenza pandemic, recent research mainly focused on influenza vaccination, especially in kidney transplantation. Lung transplantation, mycophenolate treatment, increasing age and end-stage organ failure were frequently identified as risk factors for nonresponse to immunization in general. New evidence concerning the safety of immunizing SOT recipients with live-attenuated vaccines is obtained.

SUMMARY

During this last year, more encouraging data have been published regarding safety and immunogenicity of vaccination in SOT recipients. New inventive strategies should be studied to overcome missed opportunities for vaccinating SOT candidates and recipients, and to promote the most effective vaccination schedule and follow-up.

Vaccine administration in children with chronic kidney disease

Pediatric patients with severe chronic kidney disease (CKD) on conservative treatment, on dialysis, and those with renal transplantation are at a higher risk for infectious diseases as the result of impaired immune responses against infectious agents. Infections in these patients can have drastic consequences for disease morbidity and mortality. Immunization is a crucial preventive strategy for disease management in this pediatric population. However, vaccination coverage among children with CKD remains low due to safety concerns and doubts about vaccine immunogenicity and efficacy. In this study, we reviewed why children with CKD are at higher risk of infections, the importance of vaccinations among these children, barriers to vaccinations, and recommend the best vaccination schedules. Overall, vaccines have acceptable immunogenicity, efficacy, and safety profiles in children with CKD. However, in some cases, the protective antibody levels induced by vaccines and the benefits and risks of booster vaccine doses must be individually managed. Furthermore, close contacts and household members of these children should complete age-appropriate vaccination schedules to increase the child's indirect protection.

Immunization of children with secondary immunodeficiency

The main causes of secondary immunodeficiency at a pediatric age include infectious diseases (mainly HIV infection), malignancies, haematopoietic stem cell or solid organ transplantation and autoimmune diseases. Children with secondary immunodeficiency have an increased risk of severe infectious diseases that could be prevented by adequate vaccination coverage, but vaccines administration can be associated with reduced immune response and an increased risk of adverse reactions. The immunogenicity of inactivated and recombinant vaccines is comparable to that of healthy children at the moment of vaccination, but it undergoes a progressive decline over time, and in the absence of a booster, the patients remain at risk of developing vaccine-preventable infections. However, the administration of live attenuated viral vaccines is controversial because of the risk of the activation of vaccine viruses. A specific immunization program should be administered according to the clinical and immunological status of each of these conditions to ensure a sustained immune response without any risks to the patients' health.

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.

Live virus vaccines in transplantation: friend or foe?

Solid organ and hematopoietic stem cell transplant recipients may be exposed to diseases which may be prevented through live attenuated virus vaccines (LAVV). Because of their immunosuppression, these diseases can lead to severe complications in transplant recipients. Despite increasing evidence regarding the safety and effectiveness of certain LAVV, these vaccines are still contraindicated for immunocompromised patients, such as transplant recipients. We review the available studies on LAVV, such as varicella zoster, measles-mumps-rubella, influenza, yellow fever, polio, and Japanese encephalitis vaccines in transplant patients. We discuss the current recommendations and the potential risks, as well as the expected benefits of LAVV immunization in this population.

Protective immunity and use of bortezomib for antibody-mediated rejection in a pediatric kidney transplant recipient

Standard treatments for AMR-rituximab, intravenous immunoglobulin, and/or plasmapheresis-aim to suppress the production and modulate the effect of donor-specific antibodies and remove them, respectively. Proteasome inhibitors such as bortezomib are potent therapeutic agents that target plasma cells more effectively than rituximab to reduce measurable donor-specific antibody production. Little is known in adults, and no data exist in children about effects of proteasome inhibition to treat AMR on protective antibody titers. We present a pediatric renal transplant recipient who received bortezomib for relatively early AMR and whose antibody titers to measles and tetanus were tracked. The AMR was treated successfully, and we noted no clinical decrease in the overall level of protective immunity from pretransplant baseline levels at almost one yr after AMR treatment cessation. Larger studies will elucidate more clearly how proteasome inhibition to treat AMR affects protective immunity in pediatric transplant recipients.

Parental refusal of vaccination and transplantation listing decisions: a nationwide survey

Many professional societies and research studies recommend complete vaccination before pediatric solid organ transplantation. Nevertheless, incompletely vaccinated children often receive transplants. As the number of parents refusing to vaccinate children for nonmedical reasons increases, pediatric transplantation programs face difficult listing decisions. Given the importance of psychosocial criteria in listing decisions, this study explores how parental refusal of vaccination affects those listing decisions. Surveys were emailed to individuals at 195 pediatric solid organ transplantation programs in the United States, with a 71% response rate. Forty-four respondents (39%) reported that their programs have had cases involving parental refusal of vaccination. In response to hypothetical scenarios, 93 respondents (82%) would list a child not vaccinated for medical reasons, whereas only 54 respondents (47%) would list a child whose parents refused vaccination. Only five respondents (4%) reported that their programs had written policies regarding parental refusal of vaccination. These data reveal inconsistencies across pediatric transplantation programs regarding how parental refusal of vaccination affects listing decisions and raise the issue of whether and how the reason for incomplete vaccination should be factored into listing decisions. We recommend further discussion and the development of written guidelines to unify programs' assessments of incompletely vaccinated pediatric transplantation candidates.

Varicella-zoster immunization in pediatric liver transplant recipients: safe and immunogenic

Varicella can have a severe course in immunosuppressed patients. Although prevention is fundamental, live-attenuated varicella-zoster (VZV) vaccine is not currently recommended in transplant recipients. Our aims were to (1) evaluate VZV immunity in pediatric liver transplant (LT) recipients; (2) immunize (two doses) seronegative patients post-LT; (3) monitor vaccine safety, (4) assess B and T cell vaccine responses. All patients followed at the Swiss National Pediatric LT Center were approached and 77/79 (97.5%) were enrolled (median age 7.8 years). Vaccine safety was monitored by standardized diary cards and phone calls. VZV-specific serology and CD4(+) T cells were assessed before and after immunization. Thirty-nine patients (51.1%) were seronegative including 14 children immunized pre-LT. Thirty-six of 39 seronegative patients were immunized post-LT (median 3.0 years post LT). Local (54.8%) and systemic (64.5%) reactions were mild and transient. The frequency of VZV-specific CD4(+) T cells and antibody titers increased significantly (respectively from 0.085% to 0.16%, p = 0.04 and 21.0 to 1134.5 IU/L, p < 0.001). All children reached seroprotective titers and 31/32 (97%) patients assessed remained seroprotected at follow-up (median 1.7 years). No breakthrough disease was reported during follow-up (median 4.1 years). Thereby, VZV vaccine appears to be safe, immunogenic and provide protection against disease in pediatric LT patients.