Effect of seven-valent pneumococcal conjugate vaccine on Staphylococcus aureus colonisation in a randomised controlled trial

BACKGROUND

Heptavalent pneumococcal conjugate vaccine (PCV7) shifts nasopharyngeal colonisation with vaccine serotype pneumococci towards nonvaccine serotypes. Because of the reported negative association of vaccine serotype pneumococci and Staphylococcus aureus in the nasopharynx, we explored the effect of PCV7 on nasopharyngeal colonisation with S. aureus in children and parents.

METHODOLOGY/PRINCIPAL FINDINGS

This study was part of a randomised controlled trial on the effect of PCV7 on pneumococcal carriage, enrolling healthy newborns who were randomly assigned (1:1:1) to receive PCV7 (1) at 2 and 4 months of age (2) at 2, 4 and 11 months or (3) no PCV7 (controls). Nasopharyngeal colonisation of S. aureus was a planned secondary outcome. Nasopharyngeal swabs were obtained from all children over a 2-year period with 6-months interval and from one parent at the child's age of 12 and 24 months and cultured for Streptococcus pneumoniae and S. aureus. Between July 2005 and February 2006, 1005 children were enrolled and received either 2-doses of PCV7 (n = 336), 2+1-doses (336) or no dose (n = 333) before PCV7 implementation in the Dutch national immunization program. S. aureus colonisation had doubled in children in the 2+1-dose group at 12 months of age compared with unvaccinated controls (10.1% versus 5.0%; p = 0.019). A negative association for co-colonisation of S. pneumoniae and S. aureus was observed for both vaccine serotype (adjusted odds ratio (aOR) 0.53, 95% confidence interval (CI) 0.38-0.74) and nonvaccine serotype pneumococci (aOR 0.67, 95% CI 0.52-0.88).

CONCLUSIONS/SIGNIFICANCE

PCV7 induces a temporary increase in S. aureus colonisation in children around 12 months of age after a 2+1-dose PCV7 schedule. The potential clinical consequences are unknown and monitoring is warranted.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00189020.

Airway and interstitial lung disease are distinct entities in paediatric common variable immunodeficiency

Common variable immunodeficiency (CVID) is a common primary immune deficiency, caused by undefined defects in lymphocyte function, and is treated routinely by immunoglobulin substitution. CVID complications include airway disease (AD) and interstitial lung disease (ILD). It was not known if AD and ILD in CVID have a common immunological aetiology and should be considered separate features of the same disease, or as distinct syndromes that require specialized monitoring and treatment. We used high-resolution computed tomography (CT) to diagnose AD or ILD in paediatric CVID patients. Spirometry and body plethysmography did not differentiate between ILD and AD. Patients with AD (n = 11, 20%) developed more pneumonias while children with ILD (n = 8, 15%) showed immune dysregulation characterized by autoimmune complications, more severe memory B cell reduction and expansion of non-naive cytotoxic T cells. In conclusion, ILD and AD in CVID have dissimilar clinical and immunological characteristics, suggesting distinct aetiology requiring tailored monitoring and treatment of these patient subgroups.

Hospitalization due to varicella in the Netherlands

BACKGROUND

In the Netherlands, incidence of physician's consultations and hospitalizations for varicella is low compared to other countries. Better knowledge about the severity of varicella among Dutch hospitalized patients is needed. Therefore, a medical record research was conducted among hospitalized patients with diagnosis varicella.

METHODS

Hospital admissions due to varicella in 2003-2006 were obtained from the National Medical Register. Retrospectively, additional data were retrieved from the medical record of patients hospitalized with varicella in 23 Dutch hospitals using a standardized form. Analyses were performed using descriptive statistics.

RESULTS

The study population (N = 296) was representative for all varicella admissions in the Netherlands (N = 1,658) regarding age, sex, duration of admission and type of diagnosis. Complications were recorded in 76% of the patients (37% had at least one relatively severe complication). Bacterial super infections of skin lesions (28%), (imminent) dehydration (19%), febrile convulsions (7%), pneumonia (7%) and gastroenteritis (7%) were most frequently reported. No varicella-related death occurred within the study population and 3% of the patients had serious rest symptoms.

CONCLUSIONS

It is not likely that the severity of varicella among hospitalized patients in the Netherlands differs from other countries. A considerable part of the varicella complications among hospitalized patients was rather moderate and can be treated effectively, although in a third of the hospitalized cases with complications, severe complications occurred. These data are relevant in the decision-making process regarding whether or not to introduce routine varicella vaccination in the Netherlands.

Cost effectiveness of pneumococcal conjugate vaccination against acute otitis media in children: a review

While pneumococcal conjugate vaccines have shown to be highly effective against invasive pneumococcal disease, their potential effectiveness against acute otitis media (AOM) might become a major economic driver for implementing these vaccines in national immunization programmes. However, the relationship between the costs and benefits of available vaccines remains a controversial topic. Our objective is to systematically review the literature on the cost effectiveness of pneumococcal conjugate vaccination against AOM in children. We searched PubMed, Cochrane and the Centre for Reviews and Dissemination databases (Database of Abstracts of Reviews of Effects [DARE], NHS Economic Evaluation Database [NHS EED] and Health Technology Assessment database [HTA]) from inception until 18 February 2010. We used the following keywords with their synonyms: 'otitis media', 'children', 'cost-effectiveness', 'costs' and 'vaccine'. Costs per AOM episode averted were calculated based on the information in this literature. A total of 21 studies evaluating the cost effectiveness of pneumococcal conjugate vaccines were included. The quality of the included studies was moderate to good. The cost per AOM episode averted varied from &U20AC;168 to &U20AC;4214, and assumed incidence rates varied from 20,952 to 118,000 per 100,000 children aged 0-10 years. Assumptions regarding direct and indirect costs varied between studies. The assumed vaccine efficacy of the 7-valent pneumococcal CRM197-conjugate vaccine was mainly adopted from two trials, which reported 6-8% efficacy. However, some studies assumed additional effects such as herd immunity or only took into account AOM episodes caused by serotypes included in the vaccine, which resulted in efficacy rates varying from 12% to 57%. Costs per AOM episode averted were inversely related to the assumed incidence rates of AOM and to the estimated costs per AOM episode. The median costs per AOM episode averted tended to be lower in industry-sponsored studies. Key assumptions regarding the incidence and costs of AOM episodes have major implications for the estimated cost effectiveness of pneumococcal conjugate vaccination against AOM. Uniform methods for estimating direct and indirect costs of AOM should be agreed upon to reliably compare the cost effectiveness of available and future pneumococcal vaccines against AOM.

Association of serotype with risk of death due to pneumococcal pneumonia: a meta-analysis

BACKGROUND

The 92 capsular serotypes of Streptococcus pneumoniae differ greatly in nasopharyngeal carriage prevalence, invasiveness, and disease incidence. There has been some debate, though, regarding whether serotype independently affects the outcome of invasive pneumococcal disease (IPD). Published studies have shown variable results with regard to case-fatality ratios for specific serotypes and the role of host factors in affecting these relationships. We evaluated whether risk of death due to IPD is a stable serotype-associated property across studies and then compared the pooled effect estimates with epidemiologic and biological correlates.

METHODS

We performed a systematic review and meta-analysis of serotype-specific disease outcomes for patients with pneumonia and meningitis. Study-specific estimates of risk of death (risk ratio [RR]) were pooled from 9 studies that provided serotype-specific data on pneumonia and meningitis using a random-effects method with serotype 14 as the reference. Pooled RRs were compared with RRs from adults with low comorbidity scores to evaluate potential confounding by host factors.

RESULTS

Significant differences were found in the RR estimates among serotypes in patients with bacteremic pneumonia. Overall, serotypes 1, 7F, and 8 were associated with decreased RRs, and serotypes 3, 6A, 6B, 9N, and 19F were associated with increased RRs. Outcomes among meningitis patients did not differ significantly among serotypes. Serotypes with increased RRs had a high carriage prevalence, had low invasiveness, and were more heavily encapsulated in vitro.

CONCLUSIONS

These results suggest that IPD outcome, like other epidemiologic measures, is a stable serotype-associated property.

Immune reconstitution in children following chemotherapy for haematological malignancies: a long-term follow-up

Modern intensive chemotherapy for childhood haematological malignancies has led to high cure rates, but has detrimental effects on the immune system. There is little knowledge concerning long-term recovery of the adaptive immune system. Here we studied the long-term reconstitution of the adaptive immune system in 31 children treated for haematological malignancies between July 2000 and October 2006. We performed detailed phenotypical and functional analyses of the various B and T cell subpopulations until 5 years after chemotherapy. We show that recovery of newly-developed transitional B cells and naive B and T cells occurred rapidly, within months, whereas recovery of the different memory B and T cell subpopulations was slower and incomplete, even after 5 years post-chemotherapy. The speed of B and T cell recovery was age-independent, despite a significant contribution of the thymus to T cell recovery. Plasmablast B cell levels remained above normal and immunoglobulin levels normalised within 1 week. Functional T cell responses were normal, even within the first year post-chemotherapy. This study shows that after intensive chemotherapy for haematological malignancies in children, numbers of several memory B and T cell subpopulations were decreased on the long term, while functional T cell responses were not compromised.

Pneumococcal conjugate vaccination and nasopharyngeal acquisition of pneumococcal serotype 19A strains

CONTEXT

The rapid increase in multiresistant serotype 19A as a cause of invasive and respiratory pneumococcal disease has been associated in time with the widespread implementation of 7-valent pneumococcal conjugate vaccination (PCV-7) in several countries. Because spontaneous fluctuations in time and antibiotic selective pressure may have induced this serotype 19A increase, controlled studies are needed to assess the role of PCV-7.

OBJECTIVE

To examine the association of PCV-7 vaccination and nasopharyngeal acquisition of serotype 19A pneumococci, their clonal distribution, and antibiotic susceptibility.

DESIGN, SETTING, AND PATIENTS

Post hoc per-protocol completer's analysis as part of a randomized controlled trial of nasopharyngeal Streptococcus pneumoniae carriage enrolling 1003 healthy newborns with follow-up to the age of 24 months in The Netherlands, which has low antibiotic resistance rates. The study was conducted before widespread PCV-7 implementation in infants, between July 7, 2005, and February 14, 2008. Nasopharyngeal swabs were obtained at the age of 6 weeks and at 6, 12, 18, and 24 months.

INTERVENTION

Infants were randomly assigned to receive 2 doses of PCV-7 at 2 and 4 months; 2 + 1 doses of PCV-7 at 2, 4, and 11 months; or no dosage (unvaccinated control group).

MAIN OUTCOME MEASURE

Cumulative proportion of children with nasopharyngeal acquisition of a new serotype 19A strain from 6 through 24 months of age.

RESULTS

Nine hundred forty-eight children completed the study. Fifty-four nasopharyngeal serotype 19A carriage isolates from 318 in the 2-dose group, 66 isolates from 327 in the 2 + 1-dose group, and 33 isolates from 303 in the unvaccinated were collected from 6 weeks through 24 months. The cumulative proportion who tested positive for new nasopharyngeal serotype 19A acquisition from 6 through 24 months of age was significantly higher in those having received the 2 + 1-dose PCV-7 schedule (16.2%; 95% confidence interval [CI], 12.6%-20.6%) vs those who were unvaccinated (9.2%; 95% CI, 6.5%-13.0%; relative risk [RR], 1.75; 95% CI, 1.14-2.70) but not after a 2-dose schedule (13.2%; 95% CI, 9.9%-17.4%; RR, 1.43; 95% CI, 0.91-2.25). There were 28 different sequence types identified, including 6 new types. The proportion of children with new 19A acquisition who had used antibiotics in the last 6 months (18.7%) did not differ among groups. Five isolates were penicillin-intermediate susceptible and another 3 were nonsusceptible to erythromycin and azithromycin, all in the vaccine groups.

CONCLUSION

A 2 + 1-dose PCV-7 schedule was associated with an increase in serotype 19A nasopharyngeal acquisition compared with unvaccinated controls.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00189020.

Immunity against Neisseria meningitidis serogroup C in the Dutch population before and after introduction of the meningococcal c conjugate vaccine

Background

In 2002 a Meningococcal serogroup C (MenC) conjugate vaccine, with tetanus toxoid as carrier protein, was introduced in the Netherlands as a single-dose at 14 months of age. A catch-up campaign was performed targeting all individuals aged 14 months to 18 years. We determined the MenC-specific immunity before and after introduction of the MenC conjugate (MenCC) vaccine.

Methods and Findings

Two cross-sectional population-based serum banks, collected in 1995/1996 (n = 8539) and in 2006/2007 (n = 6386), were used for this study. The main outcome measurements were the levels of MenC polysaccharide(PS)-specific IgG and serum bactericidal antibodies (SBA) after routine immunization, 4–5 years after catch-up immunization or by natural immunity. There was an increasing persistence of PS-specific IgG and SBA with age in the catch-up immunized cohorts 4–5 years after their MenCC immunization (MenC PS-specific IgG, 0.25 µg/ml (95%CI: 0.19–0.31 µg/ml) at age 6 years, gradually increasing to 2.34 µg/ml,(95%CI: 1.70–3.32 µg/ml) at age 21–22 years). A comparable pattern was found for antibodies against the carrier protein in children immunized above 9 years of age. In case of vaccination before the age of 5 years, PS-specific IgG was rapidly lost. For all age-cohorts together, SBA seroprevalence (≥8) increased from 19.7% to 43.0% in the pre- and post-MenC introduction eras, respectively. In non-immunized adults the SBA seroprevalence was not significantly different between the pre- and post-MenC introduction periods, whereas PS-specific IgG was significantly lower in the post-MenC vaccination (GMT, age ≥25 years, 0.10 µg/ml) era compared to the pre-vaccination (GMT, age ≥25 years, 0.43 µg/ml) era.

Conclusion

MenCC vaccination administered above 5 years of age induced high IgG levels compared to natural exposure, increasing with age. In children below 14 months of age and non-immunized cohorts lower IgG levels were observed compared to the pre-vaccination era, whereas functional levels remained similar in adults. Whether the lower IgG poses individuals at increased risk for MenC disease should be carefully monitored. Large-scale introduction of a MenCC vaccine has led to improved protection in adolescents, but in infants a single-dose schedule may not provide sufficient protection on the long-term and therefore a booster-dose early in adolescence should be considered.

Detection of pulmonary complications in common variable immunodeficiency

Touw CML, van de Ven AA, de Jong PA, Terheggen-Lagro S, Beek E, Sanders EAM, van Montfrans JM. Detection of pulmonary complications in common variable immunodeficiency. Pediatr Allergy Immunol 2010: 21: 793-805. (c) 2009 John Wiley & Sons A/S Pulmonary complications are frequently observed in common variable immunodeficiency (CVID). We reviewed the literature related to radiologic imaging techniques and pulmonary function tests (PFT) for diagnosing pulmonary complications in CVID. Scientific publications related to CVID (or primary hypogammaglobulinemia), pulmonary complications, PFT, chest X-ray (CXR), and high-resolution computed tomography scan (HRCT) were detected in PubMed, Embase and in reference lists of selected articles. Twenty-six articles including 1047 patients (587 patients with CVID) were reviewed. Up to 73% of CVID patients develop chronic structural pulmonary complications, of which bronchiectasis and bronchial wall thickening are most frequently detected. HRCT is the most sensitive method for identification of structural abnormalities, detecting pulmonary complications that were missed on CXR and PFT in 2-59% of patients. On PFT, obstructive flow-volume curves were most commonly found, eventually occurring in 50-94% of patients. HRCT is an important diagnostic tool for pulmonary complications in CVID at the time of diagnosis and at regular time-points during follow-up, with the proper follow-up interval yet to be determined.

Cost effectiveness of pneumococcal vaccination among Dutch infants: economic analysis of the seven valent pneumococcal conjugated vaccine and forecast for the 10 valent and 13 valent vaccines

OBJECTIVES

To update cost effectiveness estimates for the four dose (3+1) schedule of the seven valent pneumococcal conjugated vaccine (PCV-7) in the Netherlands and to explore the impact on cost effectiveness of reduced dose schedules and implementation of 10 valent and 13 valent pneumococcal vaccines (PCV-10 and PCV-13).

DESIGN

Economic evaluation comparing PCV-7, PCV-10, and PCV-13 with no vaccination using a decision tree analytic model built from data in previous studies.

SETTING

The Netherlands. Population A cohort of 180,000 newborns followed until 5 years of age.

MAIN OUTCOME MEASURES

Costs; gains in life years and quality adjusted life years (QALYs); and incremental cost effectiveness ratios.

RESULTS

Under base case assumptions-that is, assuming a five year protective period of the vaccine and no assumed net indirect effects (herd protection minus serotype replacement) among children aged over 5 years-vaccination with PVC-7 in a four dose (3+1) schedule was estimated to prevent 71 and 5778 cases of invasive and non-invasive pneumococcal disease, respectively, in children aged up to 5 years. This corresponds with a total net gain of 173 life years or 277 QALYs. The incremental cost effectiveness ratio of PCV-7 was estimated at euro113,891 ( pound98,300; $145,000) per QALY, well over the ratio of euro50,000 per QALY required for PCV-7 to be regarded as potentially cost effective. A three dose (2+1) schedule of PCV-7 reduced the incremental cost effectiveness ratio to euro82,975 per QALY. For various assumptions and including 10% of the maximum net indirect effects among individuals aged 5 years and over, PCV-10 and PCV-13 had incremental cost effectiveness ratios ranging from euro31,250 to euro52,947 per QALY.

CONCLUSIONS

The current Dutch infant vaccination programme of four doses of PCV-7 is not cost effective because of increases in invasive disease caused by non-vaccine serotypes, which reduces the overall direct effects of vaccination and offsets potential positive herd protection benefits in unvaccinated individuals. The 10 valent and 13 valent pneumococcal vaccines could have better net health benefits than PCV-7 through less replacement disease and increased herd protection. Both these effects could substantially reduce the incremental cost effectiveness ratio to possibly acceptable levels, if total programme costs can be lowered by reduced schedules, reductions in vaccine prices, or both.

Effects of pneumococcal conjugate vaccine 2 years after its introduction, the Netherlands

In the Netherlands, the 7-valent pneumococcal conjugate vaccine (PCV-7) was implemented in a 3+1-dose schedule in the national immunization program for infants born after April 1, 2006. To assess the vaccine's effectiveness, we compared disease incidence before and after vaccine implementation (June 2004-June 2006 and June 2006-June 2008, respectively). We serotyped 2,552 invasive pneumococcal isolates from throughout the Netherlands, covering 25% of the country's population. Clinical characteristics were extracted from hospital records. After June 2006, vaccine-serotype invasive pneumococcal disease (IPD) decreased 90% (95% confidence interval [CI] 68%-97%) in children age eligible for PCV-7; simultaneously, however, non-vaccine-serotype IPD increased by 71% (not significant), resulting in a 44% total net IPD reduction (95% CI 7%-66%). IPD rates did not change for other age groups. In the Netherlands, PCV-7 offered high protection against vaccine-serotype IPD in vaccinated children, but increases of non-vaccine-serotype IPD reduced net vaccine benefits.

Lymphocyte characteristics in children with common variable immunodeficiency

The diagnosis of common variable immunodeficiency (CVID) is reserved for patients who suffer from undefined B cell dysfunction. Division of the CVID population into subgroups enables research for underlying disease causes. We studied clinical features and lymphocyte characteristics in 38 children with CVID and compared them to 30 children with less severe antibody deficiencies (e.g. specific antibody deficiency combined with IgG subclass deficiency) and with 65 pediatric controls. Most pediatric immune phenotypes were comparable to adult CVID phenotypes, including a selective increase in newly formed B cells and a decrease in memory B cells and CD4(+) T cells. Eighteen percent of pediatric patients had a mutation in the TNFRSF13B gene, which requires further investigation. Finally, pediatric patients with decreased class-switched memory B cells had significantly more complications. A pediatric classification for CVID may enable prediction and early diagnosis of disease related complications and provide a framework for further etiologic research.

Invasive pneumococcal disease among adults: associations among serotypes, disease characteristics, and outcome

BACKGROUND

The Streptococcus pneumoniae polysaccharide capsule may be related to invasive pneumococcal disease (IPD) course.

METHODS

We performed a retrospective cohort study with nationally representative surveillance data from 1075 hospitalized patients with IPD from the Netherlands from 1 June 2004 through 31 May 2006 in the prevaccination era. Serotypes were grouped according to invasive disease potential, rate of the most serious clinical syndromes of meningitis and bacteremia without focus, and case-fatality rates. Multivariable logistic regression analysis was performed to obtain odds ratios adjusted for baseline confounders for the association of serotypes and these outcomes, using the serotypes with the lowest rates as reference.

RESULTS

IPD caused by serogroups with low invasive disease potential concerned meningitis or bacteremia without focus in 22% of cases, and 74% of patients had an underlying comorbidity. For highly invasive serogroups these figures were 10% (P < .01) and 56% (P < .01). Individual serotypes varied in the relative rate by which they caused meningitis or bacteremia without focus. Compared with the reference group composed of serotypes 1, 5, 7F, 15B, 20, and 33F, the group of serotypes 3, 19F, 23A, 16F, 6B, 9N, and 18C was associated with increased case-fatality rates (group adjusted odds ratio, 2.6; 95% confidence interval, 1.5-4.7).

CONCLUSIONS

The serotype appeared to be independently associated with IPD severity in adults, which indicates that careful monitoring of IPD after implementation of conjugate vaccines is necessary.

Effect of reduced-dose schedules with 7-valent pneumococcal conjugate vaccine on nasopharyngeal pneumococcal carriage in children: a randomized controlled trial

CONTEXT

The effects of reduced-dose schedules of 7-valent pneumococcal conjugate vaccine (PCV-7) on pneumococcal carriage in children are largely unknown, although highly relevant in the context of subsequent herd effects.

OBJECTIVE

To examine the effects of a 2-dose and 2 + 1-dose PCV-7 schedule on nasopharyngeal pneumococcal carriage in young children compared with controls.

DESIGN, SETTING, AND PATIENTS

A randomized controlled trial of nasopharyngeal carriage of Streptococcus pneumoniae enrolling 1003 healthy newborns and 1 of their parents in a general community in The Netherlands, with follow-up to age 24 months and conducted between July 7, 2005, and February 14, 2008.

INTERVENTION

Infants were randomly assigned to receive 2 doses of PCV-7 at 2 and 4 months; 2 + 1 doses of PCV-7 at 2, 4, and 11 months; or no dosage (control group).

MAIN OUTCOME MEASURE

Vaccine serotype pneumococcal carriage rates in infants in the second year of life.

RESULTS

At 12 months, vaccine serotype pneumococcal carriage was significantly decreased after both PCV-7 schedules, with vaccine serotype pneumococcal carriage rates of 25% (95% confidence interval [CI], 20%-30%) and 20% (95% CI, 16%-25%) in the 2-dose and 2 + 1-dose schedule groups, respectively, vs 38% (95% CI, 33%-44%) in the control group (both P < .001). At 18 months, in the 2 + 1-dose schedule group, vaccine serotype pneumococcal carriage had further decreased to 16% (95% CI, 12%-20%) and, at 24 months, to 14% (95% CI, 11%-18%; both P < .001); whereas in the 2-dose schedule group, vaccine serotype pneumococcal carriage had remained stable at 18 months (24%; 95% CI, 20%-29%), but at 24 months had further decreased to 15% (95% CI, 11%-19%; both P < .001). In the control group, vaccine serotype pneumococcal carriage remained around 36% to 38% until 24 months.

CONCLUSION

Compared with no pneumococcal vaccination, a 2 + 1-dose and 2-dose schedule of PCV-7 resulted in significant reductions of vaccine serotype pneumococcal carriage in the second year of life.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00189020.

Refined characterization and reference values of the pediatric T- and B-cell compartments

Work in the past years has led to a refined phenotypical description of functionally distinct T- and B-cell subsets. Since both lymphocyte compartments are established and undergo dramatic changes during childhood, redefined pediatric reference values of both compartments are needed. In a cohort of 145 healthy children, aged 0-18 years, the relative and absolute numbers of the various T- and B-cell subsets were determined. In addition, we found that besides thymic output, naive (CD27(+)CD45RO(-)) T-cell proliferation contributed significantly to the establishment of the naive T-cell compartment. At birth, regulatory (CD25(+)CD127(-)CD4(+)) T cells (Tregs) mainly had a naive (CD27(+)CD45RO(-)) phenotype whereas 'memory or effector-like' (CD45RO(+)) Tregs accumulated slowly during childhood. Besides the CD27(+)IgM(+)IgD(+) memory B-cell population, the recently identified CD27(-)IgG(+) and CD27(-)IgA(+) memory B-cell populations were already present at birth. These data provide reference values of the T- and B-cell compartments during childhood for studies of immunological disorders or immune reconstitution in children.

Pneumococcal conjugate vaccines for preventing otitis media

BACKGROUND

Acute otitis media (AOM) is a very common early infancy and childhood disease. The marginal benefits of antibiotics on AOM, the increasing problem of bacterial resistance to antibiotics, and the huge estimated direct and indirect annual costs associated with otitis media (OM) have prompted a search for effective vaccines to prevent AOM.

OBJECTIVES

To assess the effect of pneumococcal conjugate vaccines (PCVs) in preventing AOM in children up to 12 years of age.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, issue 2), which contains the Cochrane Acute Respiratory Infections Group's Specialised Register; MEDLINE (January 1995 to November 2007); and EMBASE (January 1995 to November 2007).

SELECTION CRITERIA

Randomised controlled trials of PCVs to prevent AOM in children aged 12 years or younger, with a follow up of at least six months after vaccination.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trial quality and two review authors extracted data.

MAIN RESULTS

We included seven trials on 7- to 11-valent PCV (with different carrier proteins). There was large heterogeneity regarding study population, type of conjugate vaccine, and outcome measures between trials, therefore, results were not pooled. The only currently licensed 7-valent PCV Prevenar with CRM197 as carrier protein (CRM197-PCV7) administered during infancy was in two studies associated with a 6% (95% confidence interval (CI) -4% to 16%) and 7% (95% CI 4% to 9%) relative reduction in risk of AOM episodes. Another 7-valent PCV with the outer membrane protein complex of Neisseria meningitidis (N. meningitidis) serogroup B as carrier protein, administered in infancy, did not reduce overall AOM episodes, while an 11-valent PCV with Haemophilus influenzae (H. influenzae) protein D as carrier protein was associated with a relative reduction in risk of AOM episodes of 34% (95% CI 21% to 44%). 9-valent PCV (with CRM197 carrier protein) administered in healthy toddlers was associated with a 17% (95% CI -2% to 33%) relative reduction in risk of OM episodes. CRM197-PCV7 followed by 23-valent pneumococcal polysaccharide vaccination administered after infancy in older children with a history of AOM showed no beneficial effect on further AOM episodes.

AUTHORS' CONCLUSIONS

Based on current evidence of the effectiveness of PCVs for the prevention of AOM, the currently licensed 7-valent PCV administered during infancy has marginal beneficial effects. Discrete reductions of 6% to 7% may mean substantial reductions from a public health perspective. Administering PCV7 in older children with a history of AOM appears to have no benefit in preventing further episodes.

Exploring the role of polymorphisms in ficolin genes in respiratory tract infections in children

Ficolins are pattern-recognition molecules that appear to be relevant for innate immune defence against infections. The ficolin genes in Caucasians are polymorphic and genetic variations may have functional consequences, both in relation to function and concentration. Low levels of Ficolin-2 have been suggested to associate with recurrent respiratory tract infections (RTI), whereas data on Ficolin-3 are still very limited. We investigated the association between variation in genes encoding Ficolin-2 (FCN2) and Ficolin-3 (FCN3) and frequency of RTI during the first 4 years of life. The study population consisted of 900 children from a large, population-based birth cohort of Dutch children, followed prospectively from birth to 4 years of age. The number of RTI was assessed by annual parental questionnaires. Nine single nucleotide polymorphisms in FCN2 and two in FCN3, all based on functionality or haplotype-tagging characteristics, were determined and haplotypes constructed. We found that single nucleotide polymorphisms in FCN2 and FCN3 were not associated with increased risk of RTI during the first 4 years of life. No difference existed between haplotype-frequencies of FCN2 and FCN3 in children grouped according to the reported number of RTI. In conclusion, at a population level, genetic variation in ficolin genes FCN2 and FCN3 do not seem to contribute to the risk of RTI in Caucasian children.

Rationale and design of CAPITA: a RCT of 13-valent conjugated pneumococcal vaccine efficacy among older adults

The burden of community-acquired pneumonia (CAP) among the elderly is high and has increased over the last decades. Streptococcus pneumoniae is the most common cause of CAP and in 10% the infection may be fatal. Although the 23-valent polysaccharide pneumococcal vaccine (23vPS) is considered effective in the prevention of invasive pneumococcal disease in the elderly population, the evidence is mainly from nonrandomised observational studies and effects on the occurrence of pneumonia have not been demonstrated. Conjugated pneumococcal vaccines which also stimulate T-cell dependent immune responses induced antibody responses in elderly persons which are similar to those induced by a primary series of 7-valent conjugated pneumococcal vaccine (7vPnC) in infants, and the response appeared similar or superior for all vaccine serotypes to that induced by 23vPS. The primary objective of the planned trial entitled CAPITA (Community Acquired Pneumonia Immunization Trial in Adults) is to establish the efficacy of a 13-valent PnC vaccine in the prevention of a first episode of vaccine-serotype specific pneumococcal CAP in 85,000 community-dwelling adult persons aged 65 years and older. This is a parallel group, randomised, placebo-controlled trial, with a 1:1 random allocation to vaccine or placebo vaccine. The occurrence of the primary outcome of vaccine-serotype specific (VT)-CAP will be established in hospitals on the basis of three sets of criteria: (1) a clinical definition of CAP; (2) independent interpretation of chest radiograph consistent with pneumonia: and (3) determination of S. pneumonia serotype. the trial will be critical to determine the position of conjugate pneumococcal vaccines in the prevention of pneumococcal disease.

Adverse reactions to simultaneous influenza and pneumococcal conjugate vaccinations in children: randomized double-blind controlled trial

In a randomized double-blind controlled trial, the safety was assessed of simultaneous administration of influenza and pneumococcal conjugate vaccines in children with previous physician-diagnosed respiratory tract infections. In total, 579 children aged 18-72 months were assigned to receive simultaneous intramuscular influenza and pneumococcal heptavalent conjugate vaccinations (IV + PV), influenza and placebo vaccinations (IV + plac) or control hepatitis B and placebo vaccinations (HepB + plac) in separate extremities. Local and systemic adverse events were recorded in parental diaries for 7 days after vaccination. No immediate adverse reactions were recorded. In most children local adverse reactions disappeared 2 days after vaccination. Local and systemic reactions were more prevalent (30% and 10% more) in the IV + PV group compared with the IV + plac and HepB + plac group. These results are important for designing future vaccination schedules.

Human herpes virus 6 plasma DNA positivity after hematopoietic stem cell transplantation in children: an important risk factor for clinical outcome

Human herpes virus 6 (HHV6) is known to reactivate after hematopoietic stem cell transplantation (HSCT), and has been suggested to be associated with severe clinical manifestations in adults. The clinical significance in children remains unclear. We investigated the incidence of HHV6 reactivation in relation to HSCT-associated morbidity and mortality in children. Between January 2004 and May 2006, 58 pediatric patients, median age 7.6 years (range: 0.1-18.1 years), received their first allogeneic HSCT. After HSCT, HHV6, Epstein Barr Virus (EBV), cytomegalovirus (CMV), and adenovirus (AdV)-plasma loads were weekly measured by quantitative PCR. Clinical features, engraftment, graft-versus-host disease (GVHD), and HSCT-associated mortality and morbidity were monitored. HHV6 reactivations were classified in group I (no reactivation), group II (loads <1000 cp/mL) and group III (loads >1000 cp/mL). CMV, EBV, Herpes Simpex Virus, Varicella Zoster Virus, and AdV-reactivations were treated according to local guidelines. HHV6 was treated only when there was clinical suspicion of disease. Thirty-six HLA-identical and 22 HLA nonidentical grafts were transplanted of which 43 were bone marrow or peripheral blood stem cells grafts and 15 were cord blood (CB) grafts. Median follow-up of the patients was 15.5 (1-35) months. HHV6 reactivation occurred in 39 of 58 (67%) patients with 31 of 39 (80%) occurring within the first 30 days post-HSCT. In 26 of 58 (45%) patients (group III), HHV 6 reactivation was significantly associated with higher nonrelapse mortality (P = .02), using multivariate Cox proportional hazard models and grade 2-4 acute GVHD (P = .03) and chronic GVHD (P = .05) in a multivariate logistic regression analysis. HHV6 reactivation is very common after HSCT in children and is associated with serious transplantation-related morbidity and mortality. Although the exact role of HHV6 reactivation after HSCT has to be elucidated, early detection and initiation of therapy might be of benefit.

Rate-difference method proved satisfactory in estimating the influenza burden in primary care visits

OBJECTIVE

To compare different methods to estimate the disease burden of influenza, using influenza and respiratory syncytial virus-(RSV) associated primary care data as an example.

STUDY DESIGN AND SETTING

In a retrospective study in the Netherlands over 1997-2003, primary care attended respiratory episodes and national viral surveillance data were used to compare the rate-difference method to other, more complex methods.

RESULTS

The influenza-associated excess estimated by the different methods varied. The estimates provided by the rate-difference model lay well within this range. According to the rate-difference method, influenza-associated primary care consultations were present for all ages, including low-risk adults. The highest influenza-associated burden was demonstrated for children below the age of 5 years. The RSV-associated primary care burden was highest in the youngest age category and well above that associated with influenza. Significant RSV-associated excess was also recorded among adults, particularly in high-risk adults and the elderly.

CONCLUSION

The straightforward rate-difference model seemed satisfactory to estimate the influenza-associated burden. Significant influenza-associated excess was demonstrated among persons not yet recommended for influenza vaccination in The Netherlands. The RSV-associated burden was highest for the youngest children, but also significant for adults.

Genetic polymorphisms in immunoresponse genes TNFA, IL6, IL10, and TLR4 are associated with recurrent acute otitis media

OBJECTIVE

Cytokines and other inflammatory mediators are involved in the pathogenesis of otitis media. We hypothesized that polymorphisms in inflammatory response genes contribute to the increased susceptibility to acute otitis media in otitis-prone children.

PATIENTS AND METHODS

DNA samples from 348 children with > or = 2 acute otitis media episodes, who were participating in a randomized, controlled vaccination trial, and 463 healthy adult controls were included. Polymorphisms in TNFA, IL1B, IL4, IL6, IL10, IL8, NOS2A, C1INH, PARP, TLR2, and TLR4 were genotyped. Genotype distributions in children with recurrent acute otitis media were compared with those in controls. Within the patient group, the number of acute otitis media episodes before vaccination and the clinical and immunologic response to pneumococcal conjugate vaccinations were analyzed.

RESULTS

The IL6-174 G/G genotype was overrepresented in children with acute otitis media when compared with controls. In the patient group, TNFA promoter genotypes -238 G/G and -376 G/G and the TLR4 299 A/A genotype were associated with an otitis-prone condition. Furthermore, lower specific anticapsular antibody production after complete vaccination was observed in patients with the TNFA-238 G/G genotype or TNFA-863 A allele carriage. Finally, the IL10-1082 A/A genotype contributed to protection from the recurrence of acute otitis media after pneumococcal vaccination.

CONCLUSIONS

Variation in innate immunoresponse genes such as TNFA-863A, TNFA-376G, TNFA-238G, IL10-1082 A, and IL6-174G alleles in the promoter sequences may result in altered cytokine production that leads to altered inflammatory responses and, hence, contributes to an otitis-prone condition.

Effect of pneumococcal vaccination on otitis media with effusion in children older than 1 year

Pneumococcal vaccines may be effective in preventing or decreasing the burden of disease related to otitis media. In study reported here, we investigated the effectiveness of pneumococcal vaccination on otitis media with effusion (OME) in children (n = 383 children aged 1-7 years) with a history of recurrent otitis media within the framework of a randomized double blind placebo controlled trial. Children were randomized to be immunized with either a 7-valent pneumococcal conjugate vaccine followed by the 23-valent pneumococcal polysaccharide vaccine, or by hepatitis A or B vaccines. The proportion of children diagnosed with OME at the scheduled follow-up visits--7, 14, 20 and 26 months after randomization--was then calculated. OME was diagnosed according to an algorithm combining tympanometry and otoscopy. The percentage of children diagnosed with OME was similar in the pneumococcal vaccination group and control group at both baseline and the follow-up visits at 7, 14, 20 and 26 months--52.9 versus 52.7, 44.9 versus 44.2, 34.9 versus 31.5, 40.8 versus 32.2 and 31.4 versus 26.1, respectively (corresponding to p-values of 0.96, 0.89, 0.51, 0.13 and 0.36, respectively). We conclude that the combined pneumococcal conjugate and the polysaccharide vaccination have no beneficial effect on OME in children aged 1 year or older with a history of recurrent otitis media. Therefore, these vaccinations are not indicated in the prevention of OME in these children.