Immunisation against varicella in end stage and pre-end stage renal failure. Trans-Pennine Paediatric Nephrology Study Group

Varicella zoster virus in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the diagnosis, prevention, and management of varicella zoster virus (VZV) in the pre- and post-transplant period. Primary varicella is an uncommon complication post-solid-organ transplant (SOT), except among pediatric transplant patients and those seronegative for VZV. As the majority of SOT recipients are seropositive for VZV, herpes zoster (HZ) occurs frequently following SOT, particularly among recipients who are older (≥65 years of age) and those receiving more intensive immunosuppression. Transplant providers should aware of the increased risk for HZ-related complications such as dissemination, organ-specific involvement, and post-herpetic neuralgia. Treatment for localized zoster is primarily given as oral regimens, but those with more complicated presentations or those at risk for dissemination should be treated initially with IV therapy. Available antiviral prophylaxis regimens and vaccination strategies for varicella and HZ among these immunosuppressed patients remain a mainstay for prevention in the pre-and post-transplant periods. Finally, we discuss important approaches to addressing post-exposure prophylaxis and infection control practices for those SOT patients with documented VZV infections.

Long-term study showed that vaccination protected paediatric renal transplant recipients from life-threatening varicella zoster virus

AIM

Renal transplant patients are particularly susceptible to highly contagious diseases due to their reduced immunity. We studied transplant recipients to gauge their varicella zoster virus (VZV) serology status over time and the outcome of any VZV infections.

METHOD

This retrospective study comprised 85 children who underwent renal transplants in Gothenburg, Sweden, from 1986 to 2014, at a mean age of eight (1-18) years. The children's medical records were reviewed and 47 had the VZV infection pre-transplant and 38 had been vaccinated pre-transplant. Clinical outcomes were available for 85 children and serology results for 72.

RESULTS

At transplantation, the VZV seropositivity rate was 50% in the vaccination group and 94% in the infection group and the antibody titres were significantly lower in the vaccination group (p = 0.031). During the median follow-up period of five years post-transplant, 28% of the vaccinated children and 97% of the infection group remained seropositive and the varicella infection affected eight children: one in the infection group and seven in the vaccination group. The herpes zoster was observed in two children in the infection group.

CONCLUSION

This study demonstrated that VZV vaccination protected from symptomatic infections to a lesser extent than natural infection, but provided effective protection from life-threatening disease.

Zoster vaccination is associated with a reduction of zoster in elderly patients with chronic kidney disease

Background

Growing epidemiological evidence demonstrates increased zoster risks in people with chronic kidney disease (CKD). Study objectives were to determine zoster vaccine effectiveness in individuals with CKD in pragmatic use.

Methods

A population-based cohort study was undertaken in a 5% random sample of US Medicare from 2007 to 2009 involving 766 330 eligible individuals aged ≥65 years who were (29 785) and were not (736 545) exposed to the zoster vaccine. Incidence rates for zoster in vaccinated and unvaccinated individuals and hazard ratios for zoster comparing vaccinated with unvaccinated were determined for individuals with CKD. Time-updated Cox proportional hazards models were used, adjusting for relevant confounders.

Results

CKD was present in 183 762 (24%) of individuals (15% of vaccinees). Adjusted vaccine effectiveness [95% confidence intervals (CIs)] in individuals with CKD was 0.49 (0.36–0.65). The adjusted vaccine effectiveness in participants with both CKD and diabetes mellitus was 0.46 (95% CI 0.09–0.68). Vaccine effectiveness estimates were similar to those previously reported for the general population [vaccine effectiveness 0.48 (95% CI 0.39–0.56)].

Conclusions

Zoster vaccine is effective against incident zoster in older individuals with CKD. Extra efforts are warranted to increase vaccine uptake in individuals with CKD given the known low uptake in these higher risk individuals.

Efficacy and tolerability of 16% subcutaneous immunoglobulin compared with 20% subcutaneous immunoglobulin in primary antibody deficiency

Multiple subcutaneous immunoglobulin (SCIG) products are available to treat primary antibody deficiency (PAD). The efficacy and tolerability of 16% SCIG (Vivaglobin(®) ) was compared with 20% SCIG (Hizentra(®) ) in PAD subjects. The study was a prospective, single-centre, open-label study of PAD subjects transitioning Vivaglobin to equivalent Hizentra doses, rounded to the nearest vial size. Comparisons included immunoglobulin (Ig)G levels; tetanus, varicella and Streptococcus pneumoniae titres; adverse events (AEs), annual infection rate and quality of life during 8 weeks of Vivaglobin and 24 weeks of Hizentra. Thirty-two subjects (aged 2-75 years) participated. Rounding to the nearest Hizentra vial size resulted in a 12·8% (± 2·9%) increase in SCIG dose. Median immunoglobulin (Ig)G level following 8 weeks of Vivaglobin was similar to 24 weeks of Hizentra (1050 versus 1035 mg/dl, respectively; P = 0·77). Both products had similar protective titres to tetanus, varicella and serotypes of S. pneumoniae, which were variable but well above protective levels. After 12 weeks of Hizentra, subjects reported fewer local site reactions compared with Vivaglobin. Switching products resulted in increased systemic AEs in some subjects but, overall, not significantly higher than during Vivaglobin treatment. Average infusion time decreased from 104·7 min (3·3 sites) with Vivaglobin to 70·7 min (2·2 sites) with Hizentra (P = 0·0005). Acute serious bacterial infections were similar. Treatment satisfaction was superior with Hizentra. Hizentra and Vivaglobin have similar pharmacokinetics and efficacy. Although transition to a different SCIG product initially increased AEs, Hizentra is well tolerated and can be infused more rapidly and with fewer sites compared to Vivaglobin.

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.

Vaccines for post-exposure prophylaxis against varicella (chickenpox) in children and adults

BACKGROUND

The prevention of varicella (chickenpox) using live attenuated varicella vaccines has been demonstrated both in randomised controlled trials (RCTs) and in population-based immunisation programmes in countries such as the United States and Australia. Many countries do not routinely immunise children against varicella and exposures continue to occur. Although the disease is often mild, complications such as secondary bacterial infection, pneumonitis and encephalitis occur in about 1% of cases, usually leading to hospitalisation. The use of varicella vaccine in persons who have recently been exposed to the varicella zoster virus has been studied as a form of post-exposure prophylaxis (PEP).

OBJECTIVES

To assess the efficacy and safety of vaccines for use as PEP for the prevention of varicella in children and adults.

SEARCH METHODS

We searched CENTRAL (2014, Issue 1), MEDLINE (1966 to March week 1, 2014), EMBASE (January 1990 to March 2014) and LILACS (1982 to March 2014). We searched for unpublished trials registered on the clinicaltrials.gov and WHO ICTRP websites.

SELECTION CRITERIA

RCTs and quasi-RCTs of varicella vaccine for PEP compared with placebo or no intervention. The outcome measures were efficacy in prevention of clinical cases and/or laboratory-confirmed clinical cases and adverse events following vaccination.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted and analysed data using Review Manager software.

MAIN RESULTS

We identified three trials involving 110 healthy children who were siblings of household contacts. The included trials varied in study quality, vaccine used, length of follow-up and outcomes measured and, as such, were not suitable for meta-analysis. We identified high or unclear risk of bias in two of the three included studies. Overall, 13 out of 56 vaccine recipients (23%) developed varicella compared with 42 out of 54 placebo (or no vaccine) recipients (78%). Of the vaccine recipients who developed varicella, the majority only had mild disease (with fewer than 50 skin lesions). In the three trials, most participants received PEP within three days following exposure; too few participants were vaccinated four to five days post-exposure to ascertain the efficacy of vaccine given more than three days after exposure. No included trial reported on adverse events following immunisation.

AUTHORS' CONCLUSIONS

These small trials suggest varicella vaccine administered within three days to children following household contact with a varicella case reduces infection rates and severity of cases. We identified no RCTs for adolescents or adults. Safety was not adequately addressed.

Varicella encephalitis and pneumonia in a patient with end stage renal failure

We describe a patient with end stage renal failure (ESRF) on hemodialysis who was admitted to our department for primary varicella infection complicated by varicella pneumonia and encephalitis. Varicella infections results in serious morbidity and mortality in ESRF dialysis and transplant patients. Evidence published thus far suggests that live attenuated varicella vaccines are effective and safe in ESRF and renal transplant patients. Worldwide a few countries have instituted guidelines for the varicella immunisation in ESRF patients. However, in the Asia Pacific Region, it has not been widely given due to the lack of national consensus guidelines. Our case depicts that primary varicella infection can occur at any time in immunosupressed patients and thus suffer serious consequences from it. With increasing burden of chronic kidney disease, Renal Physicians and Family Physicians in the Asia Pacific Region should meet and study the epidemiological data in each individual country and decide on the consensus guidelines on how the varicella vaccination can be targeted for those at risk.

2013 IDSA clinical practice guideline for vaccination of the immunocompromised host

An international panel of experts prepared an evidenced-based guideline for vaccination of immunocompromised adults and children. These guidelines are intended for use by primary care and subspecialty providers who care for immunocompromised patients. Evidence was often limited. Areas that warrant future investigation are highlighted.

Non-viral infections in children after renal transplantation

Renal transplantation has long been recognised as the gold standard treatment for children with end-stage renal failure. There has been an improvement over the years in patient and renal allograft survival because of improved immunosuppression, surgical techniques and living kidney donation. Despite reduced acute allograft rejection rates, non-viral infections continue to be a serious complication for paediatric renal transplant recipients (RTR). The risk of infections in RTR is determined by the pre-transplantation immunisation status, post-transplant exposure to potential pathogens and the amount of immunosuppression. The greatest risk of life-threatening and Cytomegalovirus infections is during the first 6 months post-transplant owing to a high immunosuppressive burden. The potential sources of bacterial infections are donor derived, transplant medium fluid, peritoneal and haemodialysis catheter and transplant ureteric stent. Urinary tract infections are frequent in patients with lower urinary tract dysfunction and can result in renal allograft damage. This review outlines the incidence, timing, risk factors, prevention and treatment of non-viral infections in paediatric RTR by critically reviewing current immunosuppressive regimens, their risk-benefit ratio in order to optimise renal allograft survival with reduced rates of rejection and infectious complications.

Immunizations in children with chronic kidney disease

Children with chronic kidney disease (CKD) are at increased risk for vaccine-preventable diseases. These patients may have a reduced response to and/or reduced duration of antibody after immunization and therefore monitoring of antibody levels or titers is indicated for some vaccines. In addition, pediatric CKD patients require immunizations not routinely provided to healthy children. Unfortunately, studies in pediatric CKD patients, including those on dialysis and awaiting kidney transplantation, have demonstrated sub-optimal immunization rates. In order to minimize the risk for vaccine-preventable disease in pediatric CKD patients, it is imperative that all who care for these patients remain abreast of the recommended childhood immunization schedule, as well as alterations to this schedule required for children with CKD, including end-stage kidney disease. This article reviews recent changes to the recommended childhood immunization schedule and alterations and additions to this schedule recommended for children with CKD. Where available, data on antibody response to immunizations in children with CKD are presented.

Varicella vaccination in pediatric kidney and liver transplantation

Reports about efficacy and safety of live-virus attenuated vaccines in patients before and after transplantation are mainly based on small patient numbers, making general recommendations for this patient population difficult. Children and adults as well as their close relatives and contact persons should be preferably immune to VZV before solid organ transplantation to avoid VZV-associated complications, thus making VZV vaccination necessary in susceptible individuals. The following literature review focused on efficacy and safety of VZV vaccination in pediatric kidney and liver transplant recipients. Review of literature also revealed that in all pediatric transplant candidates, humoral and cellular immunity against VZV should be consistently monitored to assess waning immunity under immunosuppressive treatment. This approach is desirable to estimate the risk of severe varicella disease after exposure in these patients.

Responses in children to measles vaccination associated with perirenal transplantation

BACKGROUND

Measles infection can be fatal in pediatric patients with chronic renal failure or in patients who have undergone renal transplantation, both of whom are in the immunosuppressed state. The efficacy of single, live measles vaccination in preventing infection was examined.

METHODS

Of 156 children with renal failure who underwent renal transplantation, the changes in antibody titer were investigated before and after renal transplantation in 125 children whose measles antibody titer could be examined, together with disease and vaccination histories. Live measles vaccine was administered to 42 children with negative antibody titer. The antibody seroconversion rate was then investigated in these children, along with rate of antibody maintenance and degree of antibody titer elevation.

RESULTS

Seroconversion rate was 97.6%. Antibody titers measured on HI and EIA were 72 +/- 118 fold (HI) and 36.9 +/- 31.3 (EIA), respectively. The geometric mean of the increase in antibody titer 6 months after vaccination was 15. No side-effects of vaccination were observed in any of the children.

CONCLUSIONS

Live measles vaccination of children with chronic renal failure is effective and safe, because the seroconversion rate, rate of antibody titer maintenance and degree of antibody titer elevation in children with chronic renal failure were all equivalent to those of healthy children.

Vaccines for post-exposure prophylaxis against varicella (chickenpox) in children and adults

BACKGROUND

Live attenuated varicella vaccines for the prevention of varicella (chickenpox) has been demonstrated both in randomised controlled trials (RCTs) and in population-based immunisation programmes in countries such as the United States. However, many countries do not routinely immunise children against varicella, and exposures continue to occur. Although the disease is often mild, complications such as secondary bacterial infection, pneumonitis and encephalitis occur in about 1% of cases, usually leading to hospitalisation. The use of varicella vaccine in persons who have recently been exposed to the varicella zoster virus has been studied as a form of post-exposure prophylaxis (PEP).

OBJECTIVES

To assess the efficacy and safety of vaccines for use as PEP for the prevention of varicella in children and adults.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2008, Issue 1); MEDLINE (1966 to February 2008); and EMBASE (January 1990 to February 2008).

SELECTION CRITERIA

RCTs and quasi-RCTs of varicella vaccine for PEP compared with placebo or no intervention. The outcome measures were efficacy in prevention of clinical cases and/or laboratory-confirmed clinical cases and adverse effects following vaccination.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted and analysed data using Review Manager software.

MAIN RESULTS

Three studies involving 110 healthy children who were siblings of household contacts were identified as suitable for inclusion. The studies varied in quality, study design, vaccine used, and outcomes measured and, as such, were not suitable for meta-analysis. Overall, 13 out of 56 vaccine recipients (18%) developed varicella compared with 42 out of 54 placebo (or no vaccine) recipients (78%). Of the vaccine recipients who developed varicella, the majority only had mild disease (with less than 50 skin lesions). In the three studies, most subjects received PEP within three days following exposure; too few subjects were vaccinated four to five days post exposure to ascertain the efficacy of vaccine given more than three days after exposure. No included studies reported on adverse events following immunisation.

AUTHORS' CONCLUSIONS

These small trials suggest varicella vaccine administered within three days to children following household contact with a varicella case reduces infection rates and severity of cases. No RCTs for adolescents or adults were identified. However safety was not adequately addressed.

Varicella vaccination of immunocompromised children

BACKGROUND

Exposure of immunocompromised children to varicella often requires postexposure prophylaxis. Exposures requiring this management are often not recognized. Varicella can be a severe disease when it occurs in immunocompromised children, in spite of antiviral therapy. Varicella exposure and varicella in these children can also disrupt scheduled therapy for their underlying illness. Both postexposure prophylaxis and treatment of varicella are likely to be expensive and use significant medical resources. Numerous trials have been undertaken to vaccinate children who are immunocompromised by a variety of conditions and therapies that depress their immune function.

METHODS

Clinical trials of varicella vaccine administration to immunocompromised children that were reported since 1975 were identified in the Ovid medical database. Reports were selected for analysis and discussion on the basis of their completeness and the utility of their conclusions.

RESULTS

Vaccination before immune compromise is discussed as a strategy for some settings. The obstacles, potential opportunities, and success in varicella vaccination for immunocompromised children are separately analyzed for (1) children with leukemia and other malignancies, (2) human immunodeficiency virus-infected children, and (3) children with hematopoietic stem cell or solid-organ transplantation.

CONCLUSIONS

Vaccination before immune compromise is often successful, and the vaccine-induced response is usually partially or fully protective. In many treatment settings, it is possible to safely vaccinate once the level of immune suppression has been reduced. Targets for future research are outlined. A consensus conference should be undertaken to develop guidelines for the use of varicella vaccine in immunocompromised children.

Avaliação da suscetibilidade à varicela no paciente pediátrico portador de insuficiência renal crônica

OBJETIVO: Avaliar a suscetibilidade natural à varicela de crianças e adolescentes portadores de insuficiência renal crônica (IRC). MÉTODOS: Estudo transversal de 83 pacientes com idade acima de 18 meses e inferior a 18 anos, durante 2000 e 2001, com ritmo de filtração glomerular (RFG) abaixo de 70mL/min/1,73m², portando cartão vacinal preconizado pela Fundação Nacional de Saúde e que não receberam nenhuma dose da vacina específica. Do total, três pacientes (3/83) foram excluídos, por terem recebido doses da vacina por meio de órgãos não governamentais. A sorologia foi realizada pelo método Enzyme-Linked Immuno Sorbent Assay, considerando-se títulos sorológicos protetores acima de 100mUA/mL. RESULTADOS: Os pacientes renais crônicos tinham idade mediana de 11 anos, 66% eram masculinos, 60% procedentes do próprio município de São Paulo, com RFG médio de 33,6mL/min/1,73m². O diagnóstico clínico de varicela por profissional médico ocorreu em 39 pacientes; destes, 10% se mostraram soronegativos. Dos 80 pacientes restantes, 21 (26%) apresentaram títulos não protetores para varicela. A prevalência de suscetibilidade em menores de seis anos foi 7,93 (IC95%=3,29-19,12) vezes superior à de maiores de seis anos. CONCLUSÕES: Houve diminuição da suscetibilidade à varicela com a idade. Pacientes abaixo de seis anos foram cerca de oito vezes mais suscetíveis à varicela que os renais crônicos com idade mais avançada e duas vezes mais suscetíveis do que a população pediátrica brasileira de mesma idade.

Demand for evaluation of vaccination antibody titers in children considered for renal transplantation

Vaccinations are recommended for achieving protection against vaccine-preventable infections in solid-organ transplant recipients. In order to evaluate the protection at the time of renal transplantation, the antibody titers against measles, mumps, rubella, varicella, hepatitis B, diphtheria, and tetanus were determined in 35 children one month prior to transplantation. Only 26% of patients on dialysis listed for transplantation showed protective antibodies against all tested pathogens. Particularly, low protection was found for hepatitis B. Children younger than four yr showed significantly lower protective antibody titers compared with older children for almost all vaccines. Children who completed vaccination in the last six months to six yr prior to renal transplantation showed higher rates of protective antibody titers against all pathogens compared with children who had vaccination more than six yr before transplantation. Preventive strategies in children with chronic renal failure include repeated measurements of serum antibodies and appropriate revaccination if titers decline. Our results underline the demand for continuous surveillance of specific antibody titers against vaccine-preventable diseases in the risk group of renal transplant recipients.

The use of vaccines in adult patients with renal disease

In patients with renal disease, infection remains among the most common causes of morbidity and mortality. Alterations in the function of the immune system, as well as unique exposures of this patient population, account for the increased risk. Vaccination is an invaluable tool in preventing many infectious diseases. Unfortunately, responsiveness to vaccination in patients with renal disease can be diminished. In the present review, we examine the available evidence on the use of vaccinations in adult patients at different stages of chronic kidney disease. We address efficacy, clinical outcomes, and potential costs of individual vaccinations and provide our recommendations based on the literature reviewed. We also identify areas in which additional research is needed.

Fulminating varicella despite prophylactic immune globulin and intravenous acyclovir in a renal transplant recipient: should renal patients be vaccinated against VZV before transplantation?

We describe a case of fulminating varicella despite prophylactic immune globulin and intravenous acyclovir in a renal transplant recipient. This promoted a survey of all 383 adult patients awaiting a renal transplant in Scotland, which showed a low level of Varicella zoster virus (VZV) awareness but a willingness to consider vaccination if non immune. 359/363 serum samples tested were seropositive for VZV antibody giving a susceptibility to VZV of 1.2%. Although data on vaccination in adults with chronic kidney disease are limited, expert opinion is of the view that the benefits of vaccinating immunocompetent seronegative patients before transplantation are likely to outweigh the risks. We believe that adult patients awaiting a transplant in the UK should be tested for their susceptibility to VZV and that early vaccination should be offered to those who are both immunocompetent and seronegative.

Immunization of pediatric solid-organ transplantation candidates: immunizations in transplant candidates

Many children who receive solid-organ transplants have not completed their primary immunizations prior to transplantation. This leaves pediatric transplant recipients susceptible to the vaccine preventable illness of childhood, which if acquired post-transplantation are associated with increased rates of complications, hospitalization, graft rejection and mortality. The administration of vaccines to transplant candidates earlier and more rapidly than in the healthy child will improve vaccination rates among transplant recipients while not compromising immunogenicity. The recommended vaccines and vaccine schedule are discussed in detail.

Loss of antibodies to measles and varicella following solid organ transplantation in children

The objective of this study was to determine if loss of antibodies to measles and to varicella occurs in pediatric solid organ transplant recipients. Antibodies were measured in eight hepatic, four cardiac, and six renal transplant patients who had antibodies to measles prior to transplantation, and in six hepatic, five cardiac, and seven renal transplant patients who had antibodies to varicella prior to transplantation. Within 6 months of the transplant, loss of antibodies occurred in four of 18 patients who were seropositive for measles prior to transplantation (22.2%) and in two of 18 patients who were seropositive for varicella prior to transplantation (11.1%). In conclusion, serology for measles and varicella should be considered annually following solid organ transplantation so that appropriate advice can be given to patients who have seroreverted.

Immunisation in the current management of cystic fibrosis patients

Although no special recommendations exist, clearly patients with cystic fibrosis (CF) can benefit from immunisation. We reviewed the literature regarding vaccination in CF and other chronic diseases. CF subjects should follow national immunisation programmes without delay to obtain optimal vaccination coverage. Indeed they may escape normal programmes due to frequent hospital admissions and school absenteeism and may be more at risk to get "vaccine-controlled" diseases at any age. There is no uniform European immunisation schedule for basic infant and childhood vaccines or for vaccines against hepatitis A (HAV) and B (HBV), varicella (VZ) and booster vaccinations. HAV and HBV vaccination is appropriate in CF as recommended in general for patients with chronic liver disease (CLD). Varicella (VZ) vaccination is not recommended in all European countries. There are no recent data about possible worsening of pulmonary status following VZ in CF, but it is known to cause pulmonary damage in non-CF adults and to be potentially fatal post transplantation and during steroid treatment. Therefore it is recommended at least for seronegative adolescents and transplant candidates. Influenza vaccine is recommended annually for CF patients aged > or =6 months. Pneumococcal vaccine is generally indicated for CF patients. RSV infection might play a role in the initial Pseudomonas colonization and the decline in pulmonary function. However no RSV vaccine is available at present. There are no recommendations for palivizumab in CF as an alternative but expensive prophylaxis. Anti-bacterial vaccinations protecting directly against Pseudomonas aeruginosa colonisation are promising for the future, potential candidates are currently being assessed in phase III clinical trials. More studies are needed to complete recommendations especially for CF adults and transplant candidates.

Seroprevalence of antibodies against varicella-zoster virus and response to the varicella vaccine in pediatric renal transplant patients

The severity of varicella-zoster virus (VZV) in immunocompromised children, especially in those receiving renal transplants, is well known. However, the use of live attenuated virus vaccine in this population is controversial. This study aimed to: (i) assess the immunization status of pediatric renal transplant recipients at our center; (ii) determine the anti-VZV antibody titers in such patients; (iii) evaluate the response to VZV vaccine in seronegative children and in those who present low antibody titers (defined as <500 mAU/mL). Vaccinated children were monitored for adverse effects for 8 wk after vaccination. Fifty patients with a mean age of 13.7 yr (range, 3-17 yr) were enrolled. In 49, blood samples were collected and antibodies were screened using ELISA. Seropositivity to VZV was found in 43 (88%), and antibody titers were >/=500 mAU/mL in 37 (75.5%). Of the 12 children who were eligible for vaccination and had antibody titers <500 mAU/mL, one developed varicella before vaccination, two did not meet the inclusion criteria, and three parents refused the vaccination. In the six vaccinated children, there were no adverse reactions to the vaccine, and four (66.6%) responded with anti-VZV titers >/=500 mAU/mL 6-8 wk after vaccination. In conclusion, after renal transplantation, varicella vaccine is safe with a 66% rate of conversion to high antibody titers.

Immunization in children with chronic renal failure: a practical approach

The prevention of systemic viral and bacterial infections by effective vaccination represents an essential task of pediatric nephrologists caring for children with chronic renal failure (CRF) undergoing renal transplantation (RTPL) with life-long immunosuppression. This review addresses three issues: risk of vaccine-preventable diseases, safety, immunogenicity, and clinical efficacy of available vaccines, and implementation of immunization guidelines. Infections (including vaccine-preventable infections) represent the leading cause of morbidity and mortality in children on dialysis and after RTPL. Vaccination in children with CRF and after RTPL is safe and does not cause reactivation of an immune-related renal disease or rejection after RTPL. Children with CRF generally produce protective serum antibodies to primary vaccinations with killed or component vaccines and live virus vaccines; some children on dialysis and after RTPL may not respond optimally, requiring repeated vaccination. Proof of vaccine efficacy is absence of disease, which can only be confirmed in large cohort studies. A few observational studies provide evidence that vaccination has contributed significantly, at least in the western hemisphere, to the low prevalence of vaccine-preventable diseases among children with CRF. Close cooperation between the local pediatrician/practitioner and the pediatric nephrologist is essential for successful implementation of the vaccination schedule.

A review of the varicella vaccine in immunocompromised individuals

BACKGROUND

Individuals with underlying cell-mediated immunodeficiency disorders are at high risk of developing severe, life-threatening illness associated with varicella-zoster virus infection. A live-attenuated varicella vaccine is recommended for routine childhood immunisation in some countries. In healthy children, the vaccine is efficacious and safe but because immunocompromised individuals may be unable to limit replication of live-attenuated vaccine viruses, the varicella vaccine is not recommended for them and there are few exceptions.

OBJECTIVES

The purpose of this paper is to review the published studies addressing the use of the varicella vaccine in people with cell-mediated immunodeficiency disorders.

METHODS

A computerised search on the PubMed database was used to collect the relevant papers published up to March 2003.

RESULTS

The varicella vaccine has been extensively studied in susceptible children with acute lymphoblastic leukaemia in remission, but studies involving individuals with other immunodeficiency disorders are scarce. Some of the current recommendations are based on very few and small studies with short follow-up. Immunocompromised individuals should be given the varicella vaccine only with complete knowledge of their clinical and immunological conditions and after considering the risks of natural infection and vaccination.

Consensus: varicella vaccination of healthy children--a challenge for Europe

The seriousness of varicella-zoster virus (VZV) infection as a public health issue is becoming clearer as country-specific epidemiologic and pharmacoeconomic data become available. In Germany, for example, studies have shown that >5.5% of immunologically healthy individuals develop varicella-related complications such as bacterial superinfections, acute neurologic disorders, pneumonia, bronchitis and otitis media; whereas in Italy, 3.5 to 5% of childhood cases of varicella cause complications such as upper respiratory tract and cutaneous infections. Varicella vaccines are now available. These live attenuated Oka strain vaccines have been shown in extensive studies to be highly immunogenic and well-tolerated in immunocompetent and immunocompromised children, with seroconversion rates ranging from 94 to 100% and 53 to 100%, respectively. These vaccines are also highly effective against clinical disease. These considerations led to a reevaluation of varicella vaccination policies. A routine varicella vaccination program targeting healthy children has already been implemented in the US, and data produced are encouraging and valuable. Similar strategies have not yet been adopted across Europe. The European Working Group on Varicella (EuroVar) was formed in 1998 to address the issues surrounding varicella epidemiology in Europe. After a series of meetings, the EuroVar members prepared a consensus statement recommending routine varicella vaccination for all healthy children between 12 and 18 months and to all susceptible children before their 13th birthday, in addition to catch-up vaccination in older children and adults who have no reliable history of varicella and who are at high risk of transmission and exposure. However, such a policy is recommended only if a very high coverage rate can be achieved. This could be reached with a measles-mumps-rubella-varicella combined vaccine.

Primary varicella after transplantation

A 51-year-old white woman 6 months status post cadaveric renal transplant developed a mild case of primary varicella-zoster (VZ). It is hypothesized that the limited nature of her illness was due to infection with vaccine-type VZ virus instead of wild-type VZ. Approximately 1 month prior, she had daily household contact with a child who had developed a rash after immunization with live attenuated varicella vaccine. This case highlights several important questions. Should special precautions be undertaken with renal transplant recipients naive to varicella infection after vaccination of household contacts? Should pretransplant immunization with varicella vaccine be performed routinely in naive patients? Should naive patients transplanted and maintained on immunosuppressive therapy be vaccinated? Until there are clinical trials to answer these questions, it may be instructive to consider the recommendations for pediatric and immunocompromised patients.

Auditory neural responses to click stimuli of different rates in the brainstem of very preterm babies at term

Auditory neural responses to acoustic stimuli of different rates were studied by analyzing changes in brainstem auditory evoked responses (BAER) with increasing repetition rate of clicks, or rate-dependent changes, in 62 very preterm babies (gestation 24-32 wk). None had perinatal asphyxia or major complications at the time of testing (37-42 wk postconceptional age) to exclude their possible effects on the recorded BAER. As the rate of clicks was increased from 21/s to 51/s and 91/s, I-V interpeak interval in these babies increased similarly to that in normal term neonates. The rate-dependent change decreased significantly in I-III interval, but increased significantly in III-V intervals and III-V/I-III interval ratio (all p < 0.01). At all three rates of clicks, the I-V interval, the most commonly used BAER variable, tended to increase slightly but did not differ significantly from the term neonates. The I-III interval decreased significantly at higher click rates (ANOVA p < 0.05 at 51/s and < 0.001 at 91/s), whereas the III-V interval and III-V/I-III interval ratio increased significantly at all 21/s, 51/s, and particularly 91/s (p < 0.01-0.001). No abnormalities were found in wave V amplitude at any rates. These results suggest that very preterm babies have an advanced peripheral development of the brainstem auditory pathway but a retarded central development or central impairment. A nearly normal I-V interval does not exclude a possible abnormality in its subcomponents (I-III and III-V intervals). In babies who have a normal BAER at a conventionally used low rate of clicks, we cannot exclude an abnormal BAER at higher rates.

Varicella vaccination in pediatric kidney transplant candidates

Existing studies support the use of varicella vaccine in a two-dose regimen in patients with renal disease prior to transplantation. Levels of anti-varicella zoster virus antibody should be monitored on a regular basis after immunization, and where a loss of a previously protective antibody titer occurs, a third booster dose should be considered pretransplant. Further data need to be collected regarding the use of the vaccine in seronegative patients who have already undergone transplantation.

Opportunistic infections after renal transplantation

Opportunistic infection is a serious clinical complication in patients receiving immunosuppressive therapy after kidney transplantation. This article deals with some of the possible infectious agents that were recently encountered at our transplantation centre in Düsseldorf, Germany. Opportunistic organsims such as human herpesviruses 6-8, polyomavirus, parvovirus B19, varicella zoster virus, Nocardia and Listeria monocytogenes are rare but severe complications that are presented in this overview. As a result of the use of new immunosuppresive drugs like tacrolimus and mycophenolate mofetil these infections are now seen more frequently, so they should always be included in differential diagnostic considerations. New diagnostic procedures and new treatment strategies should allow early detection and successful treatment of opportunistic infections in the majority of kidney transplant recipients.

Immunologic defects and vaccination in patients with chronic renal failure

Patients with chronic renal failure suffer from defective host defenses which are directly the result of the renal impairment, in addition to those dependent on the primary illness leading to the renal failure. The mechanisms underlying the defective responses in phagocytic cells, lymphocytes and antigen processing are likely due to either failure to adequately eliminate suppressive compounds by the defective kidneys or to improper metabolic processing of the factors by the damaged renal parynchema. That some of the defects are reversed by transplantation and not dialysis suggests that renal parenchymal metabolic activities may be involved, although it is also possible that functioning glomerular cells are capable of filtering substances that membranes are not currently capable of eliminating. The current strategy for dealing with the immunodeficiency appears to be totally based on developing means to circumvent the defective function. The other approach, correction of the impaired function, cannot be even considered until the mechanisms underlying the defective function of the cells involved in defenses are better delineated. It seems possible that one or a few compounds are pivotal in altering the function of all the affected cell lines, since, with only a small amount of effort, it is possible to relate the dysfunction to abnormal cell membrane functions in phagocytic cells, dendritic cells and lymphocytes. Until the biochemical basis of the dysfunction of all the cell types affected are better defined, such exercises cannot be translated into better management of patients with chronic renal failure. Proper function of host defenses requires that appropriate cells can properly respond to threats to host viability. For the cells of the immune system (phagocytes and lymphocytes) this means that their response to regulatory molecules be appropriate, that their mobility be normal, that their adherence to substrates be preserved, and that they can generate the appropriate response to the challenge. For neutrophils, for example, it is necessary that they recognize and mobilize appropriately to chemotactic stimuli, that they be able to adhere to and migrate through endothelial lining, that their phagocytic activity be sufficient, and that they can kill and degrade endocytosed particles and generate appropriate secretions. Similar lists of requirements for good function can be generated for any cell type in the immune defense system. Uremia, as well as currently available treatments for uremia, directly or indirectly alters the function of all phases of appropriate immune cell function. Defective host responses in uremia have been recognized for decades and there has been considerable effort in the past decade to better define the extent and mechanisms of impaired defenses. Despite the multitude of major defects in humoral, cellular, and inflammatory processes, uremic patients who are cared for today, although they remain at higher risk of serious infectious complications, can and do maintain a good quality of life, with most remaining free of major infections for years and decades.

Vaccines for transplant recipients

Immune dysregulation and immunosuppression regimens impact on the ability of transplant recipients to respond to immunizations. The distinct challenges of immunizations to benefit stem cell transplant recipients and solid organ transplant recipients are discussed separately. Recommended vaccines for stem cell transplant recipients and solid organ transplant candidates are suggested. New approaches to consider to enhance immune responses of transplant recipients are discussed.

Infections associated with dialysis and transplantation

Infection within the abdominal wall and peritonitis are still important causes of morbidity which ultimately limit the use of peritoneal dialysis in end-stage renal failure. Similarly disastrous complications resulting in loss of access can follow infection in venous cannulae and artificial arteriovenous fistulae, particularly in synthetic vascular grafts. Important publications continue to underline the mechanism of reduced resistance to infection by uraemic patients. After renal transplantation bacterial infection is common and predictable. However, immunosuppressed recipients are particularly susceptible to viral and fungal infection. Arguably infection of all types can induce organ rejection.