Transient suppression of atopy in early childhood is associated with high vaccination coverage

Infants' immunisations, their timing and the risk of allergic diseases (INITIAL): an observational prospective cohort study protocol

INTRODUCTION

Vaccinations are considered to have a large impact on disease control, hence a multitude of vaccines in infancy is recommended. Retrospective studies suggest a possible relation between timing, kind or number of vaccines given in the first year of life and the subsequent incidence of allergic diseases. It must be clarified whether a causal relationship exists to ensure safety and reduce vaccine hesitancy.

METHODS AND ANALYSIS

Due to the high recommendation rate of vaccines, a long-term randomised controlled trial is not considered as ethically acceptable. Therefore, this study aims to observe prospectively the allergic incidence at the age of 5 years after various vaccine interventions in the early months of life.Parents of infants up to the age of 4-6 weeks will be recruited before the first recommended vaccination. Relevant prognostic factors for allergies, status of immunisation and general health will be evaluated up to the age of 5.Allergic symptoms will be assessed by the International Study of Asthma and Allergies in Childhood-questionnaire and a medical confirmation of the allergy is mandatory.The main objective is to compare the incidence of asthma, atopic dermatitis, rhinoconjunctivitis, food allergy or any of these atopies at the age of 5 between infants who were not vaccinated or were vaccinated according to recommendations in the first year of life.The sample size calculation with about 4000 participants can prove a 5% difference to the basic prevalence with about 80% power and global 5% alpha error for the five primary endpoints adjusting according to Bonferroni-Holm and assuming a rate of 10% not early vaccinated infants.

ETHICS AND DISSEMINATION

The study was registered (DRKS00029677) and has received approval by the ethics committee of Universität Witten/Herdecke (no. 113/2022). The results will be published.

Association Between Aluminum Exposure From Vaccines Before Age 24 Months and Persistent Asthma at Age 24 to 59 Months

OBJECTIVE

To assess the association between cumulative aluminum exposure from vaccines before age 24 months and persistent asthma at age 24 to 59 months.

METHODS

A retrospective cohort study was conducted in the Vaccine Safety Datalink (VSD). Vaccination histories were used to calculate cumulative vaccine-associated aluminum in milligrams (mg). The persistent asthma definition required one inpatient or 2 outpatient asthma encounters, and ≥2 long-term asthma control medication dispenses. Cox proportional hazard models were used to evaluate the association between aluminum exposure and asthma incidence, stratified by eczema presence/absence. Adjusted hazard ratios (aHR) and 95% confidence intervals (CI) per 1 mg increase in aluminum exposure were calculated, adjusted for birth month/year, sex, race/ethnicity, VSD site, prematurity, medical complexity, food allergy, severe bronchiolitis, and health care utilization.

RESULTS

The cohort comprised 326,991 children, among whom 14,337 (4.4%) had eczema. For children with and without eczema, the mean (standard deviation [SD]) vaccine-associated aluminum exposure was 4.07 mg (SD 0.60) and 3.98 mg (SD 0.72), respectively. Among children with and without eczema, 6.0% and 2.1%, respectively, developed persistent asthma. Among children with eczema, vaccine-associated aluminum was positively associated with persistent asthma (aHR 1.26 per 1 mg increase in aluminum, 95% CI 1.07, 1.49); a positive association was also detected among children without eczema (aHR 1.19, 95% CI 1.14, 1.25).

CONCLUSION

In a large observational study, a positive association was found between vaccine-related aluminum exposure and persistent asthma. While recognizing the small effect sizes identified and the potential for residual confounding, additional investigation of this hypothesis appears warranted.

Whole-cell pertussis vaccine in early infancy for the prevention of allergy in children

BACKGROUND

Atopic diseases are the most common chronic conditions of childhood. The apparent rise in food anaphylaxis in young children over the past three decades is of particular concern, owing to the lack of proven prevention strategies other than the timely introduction of peanut and egg. Due to reported in vitro differences in the immune response of young infants primed with whole-cell pertussis (wP) versus acellular pertussis (aP) vaccine, we systematically appraised and synthesised evidence on the safety and the potential allergy preventive benefits of wP, to inform recommendation for future practice and research.

OBJECTIVES

To assess the efficacy and safety of wP vaccinations in comparison to aP vaccinations in early infancy for the prevention of atopic diseases in children.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, Ovid MEDLINE, Embase, and grey literature. The date of the search was 7 September 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) that reported the occurrence of atopic diseases, and RCTs only to assess safety outcomes. To be included studies had to have at least six months follow-up, and involve children under 18 years old, who received a first dose of either wP (experimental intervention) or aP (comparator) before six months of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies for eligibility, extracted the data, and assessed risk of bias using standard Cochrane methods. We assessed the certainty of the evidence using GRADE. Our primary outcomes were diagnosis of IgE-mediated food allergy and all-cause serious adverse events (SAEs). Secondary outcomes included: diagnosis of not vaccine-associated anaphylaxis or urticaria, diagnosis of asthma, diagnosis of allergic rhinitis, diagnosis of atopic dermatitis and diagnosis of encephalopathy. Due to paucity of RCTs reporting on the atopic outcomes of interest, we assessed a broader outcome domain (cumulative incidence of atopic disease) as specified in our protocol. We summarised effect estimates as risk ratios (RR) and 95% confidence intervals (CI). Where appropriate, we pooled safety data in meta-analyses using fixed-effect Mantel-Haenszel methods, without zero-cell corrections for dichotomous outcomes.

MAIN RESULTS

We identified four eligible studies reporting on atopic outcomes, representing 7333 children. Based on a single trial, there was uncertain evidence on whether wP vaccines affected the risk of overall atopic disease (RR 0.85, 95% CI 0.62 to 1.17) or asthma only (RR 1.04, 95% CI 0.59 to 1.82; 497 children) by 2.5 years old.Three NRSIs were judged to be at serious or critical risk of bias due to confounding, missing data, or both, and were ineligible for inclusion in a narrative synthesis.  We identified 21 eligible studies (137,281 children) that reported the safety outcomes of interest. We judged seven studies to be at high risk of bias and those remaining, at unclear risk.  The pooled RR was 0.94 for all-cause SAEs (95% CI 0.78 to 1.15; I² = 0%; 15 studies, 38,072 children). For every 1000 children primed with a first dose of wP, 11 had an SAE. The corresponding risk with aP was 12 children (95% CI 9 to 13). The 95% CI around the risk difference ranged from three fewer to two more events per 1000 children, and the certainty of the evidence was judged as moderate (downgraded one level for imprecision). No diagnoses of encephalopathy following vaccination were reported (95% CI around the risk difference - 5 to 12 per 100,000 children; seven primary series studies; 115,271 children). The certainty of the evidence was judged as low, since this is a serious condition, and we could not exclude a clinically meaningful difference.

AUTHORS' CONCLUSIONS

There is very low-certainty evidence that a first dose of wP given early in infancy, compared to a first dose of aP, affects the risk of atopic diseases in children. The incidence of all-cause SAEs in wP and aP vaccinees was low, and no cases of encephalopathy were reported. The certainty of the evidence was judged as moderate for all-cause SAEs, and low for encephalopathy. Future studies should use sensitive and specific endpoints of clinical relevance, and should be conducted in settings with high prevalence of IgE-mediated food allergy. Safety endpoints should prioritise common vaccine reactions, parental acceptability, SAEs and their potential relatedness to the dose administered.

Childhood vaccination and allergy: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

As the rise in prevalence of allergic diseases worldwide corresponds in time with increasing infant vaccination, it has been hypothesized that childhood vaccination may increase the risk of allergic disease. We aimed to synthesize the literature on the association between childhood vaccination and allergy.

DESIGN

We searched the electronic databases PubMed and EMBASE (January 1946-January 2018) using vaccination and allergy terms.

METHODS

Two authors selected papers according to the inclusion criteria. Pooled effects across studies were estimated using random-effects meta-analysis. Due to inadequate number of homogeneous publications on newer and underused vaccines, meta-analysis was limited to allergic outcomes following administration of (Bacillus Calmette-Guérin) BCG, measles or pertussis vaccination. The review was prospectively registered in the PROSPERO systematic review registry (NO: CRD42017071009).

RESULTS

A total of 35 publications based on cohort studies and 7 publications based on randomized controlled trials (RCTs) met the inclusion criteria. RCTs: From 2 studies, early vaccination with BCG vaccine was associated with a reduced risk of eczema (RR = 0.83; 95% CI = 0.73-0.93; I²  = 0%) but not food allergy or asthma. No association was found between pertussis vaccine and any allergic outcome based on a single RCT.

COHORT STUDIES

Childhood measles vaccination was associated with a reduced risk of eczema (RR = 0.65; 95% CI = 0.47-0.90, I²  = 0.0%), asthma (RR = 0.78; 95% CI = 0.62-0.98, I²  = 93.9%) and, with a similar, statistically non-significant reduction in sensitization (RR = 0.78; 95% CI = 0.61-1.01, I²  = 19.4%).

CONCLUSIONS

We found no evidence that childhood vaccination with commonly administered vaccines was associated with increased risk of later allergic disease. Our results from pooled analysis of both RCTs and cohort studies suggest that vaccination with BCG and measles vaccines were associated with a reduced risk of eczema.

Vaccines do not cause atopic dermatitis: A systematic review and meta-analysis

BACKGROUND

Previous studies found conflicting results about the association of vaccinations and likelihood of atopic dermatitis (AD).

OBJECTIVES

To determine whether vaccinations increase the likelihood of AD.

METHODS

A systematic review was performed of all published studies in MEDLINE, EMBASE, LILACS, Scopus, and Web of Science databases. At least 2 reviewers conducted title/abstract, full-text review, and data extraction. Quality of evidence was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Forty-four studies met inclusion criteria; 37 had sufficient data for meta-analysis. There were no associations any vaccine regimen (random-effects logistic regression: odds ratio [95% confidence interval]: 0.961 [0.822-1.124]; n = 21 studies) BCG (0.927 [0.701-1.226]; n = 8), pertussis (0.790 [0.416-1.499]; n = 4), single (1.031 [0.920-1.155]; n = 17) or multiple vaccines (0.902 [0.608-1.338]; n = 7) with likelihood of AD. This remained true in studies with high-quality (NOS ≥ 7) (OR [95% CI]: 0.941 [0.793-1.117]; n = 13 studies) or low-quality (NOS < 7) (OR [95% CI]: 1.058 [0.669-1.674]; n = 8 studies).

LIMITATIONS

No randomized controlled trials.

CONCLUSIONS

No vaccine regimen was consistently associated with developing AD.

An integrative medicine review of primary prevention of allergy in pediatrics

The prevalence of allergic disease has been rapidly increasing in the developed world for over fifty years. The prevention of allergic disease remains one of the most elusive topics in medicine. Integrative medicine emphasizes prevention of disease and utilizes many interventions to help modify long-term outcomes of health. Primary prevention refers to the arrest of manifestations of a disease before they present clinically. Preventing allergy is not simply about preventing sensitization, but also about developing tolerance. This narrative review article will discuss integrative medicine approaches that may help to prevent atopic disease in the pediatric population. It is organized chronologically to aid in counseling patients: 1) prevention during pregnancy and 2) prevention after birth. While research into allergy prevention is in its infancy, Integrative Medicine is well-suited to provide many insights into the prevention and mitigation of atopic disease.

PFAS Environmental Pollution and Antioxidant Responses: An Overview of the Impact on Human Field

Due to their unique properties, perfluorinated substances (PFAS) are widely used in multiple industrial and commercial applications, but they are toxic for animals, humans included. This review presents some available data on the PFAS environmental distribution in the world, and in particular in Europe and in the Veneto region of Italy, where it has become a serious problem for human health. The consumption of contaminated food and drinking water is considered one of the major source of exposure for humans. Worldwide epidemiological studies report the negative effects that PFAS have on human health, due to environmental pollution, including infertility, steroid hormone perturbation, thyroid, liver and kidney disorders, and metabolic disfunctions. In vitro and in vivo researches correlated PFAS exposure to oxidative stress effects (in mammals as well as in other vertebrates of human interest), produced by a PFAS-induced increase of reactive oxygen species formation. The cellular antioxidant defense system is activated by PFAS, but it is only partially able to avoid the oxidative damage to biomolecules.

Vaccination and Allergic Sensitization in Early Childhood - The ALADDIN Birth Cohort

BACKGROUND

The increasing incidence of allergic diseases highlights the importance of finding underlying mechanisms. Early vaccination has been suggested as one influential factor. However, it is difficult to find a study group with a large variation between subjects concerning compliance to the official vaccination program. The anthroposophic lifestyle is of interest in this context. Moreover, cohort studies show that children of families with this lifestyle run a lower risk of allergic sensitization and allergy-related disease.

METHODS

From the prospective birth cohort ALADDIN we included one group from the anthroposophic community, with restrictive attitudes concerning vaccinations, and two other groups of age-matched children with more conventional parental lifestyles. In all, 466 children were followed from birth to five years of age. Detailed vaccination data and blood samples were collected at six months, one, two, and five years. Information was also obtained on risk factors for allergy. The outcome variable, allergic sensitization was defined as allergen-specific serum IgE levels ≥ 0.35 kU_A/L.

FINDINGS

In a logistic regression model adjusted for socio-demographics and established allergy risk factors, vaccination at later age or having a lower number of injections or vaccines were associated with low OR for allergic sensitization during the first year of life. However, after adjustment for anthroposophic lifestyle, no statistically significant associations remained. The adjusted OR for sensitization at five years of age in children not receiving any vaccinations (n = 54) was 0.98 [95% CI 0.38-2.57].

INTERPRETATION

We found no support for an association between early childhood vaccination and subsequent allergic sensitization. Our findings do not support scepticism towards early childhood vaccination motivated by allergy risk.

Whole-cell pertussis vaccine (DTwP) has no influence on allergic diseases and atopic sensitization in children

Introduction

Vaccine opponents indicate that the infant’s immune system is inadequately developed to handle multiple vaccines which may overwhelm the immune system, leading to allergic diseases.

Aim

To verify the association between the vaccine antigen overload derived from DTwP and the development of atopic sensitization and allergic diseases.

Material and methods

Data from an earlier established birth cohort in Krakow, followed up to the 6^th year of life were used. Allergic diseases such as eczema, hay fever and asthma were diagnosed by a physician and reported every half a year from the 1^st to 6^th year of life by the child’s parent. Skin prick tests (SPT) were performed in children at 5 years of age. The data on infants’ vaccination were extracted from the physician’s records. The status of vaccine antigen exposure was based on different types of vaccines against pertussis (DTwP or DTaP) in a primary course. Results were determined by multiple logistic regression, adjusted to potential confounders.

Results

The analyzed population consisted of 234 children: 53.4% – boys and 46.6% – girls. Infants up to the age of 8 months were vaccinated with the primary course against pertussis, with DTwP – 60.7%, DTaP – 32.9% and further 6.4% with a mixed course (DTwP + DTaP). There were no significant relationships between any of vaccination groups and allergic disease and allergen sensitivity in the multiple logistic regression model with adjustment to potential confounders.

Conclusions

The exposure to a large number of vaccine antigens derived from DTwP has no influence on the development of allergic diseases and atopic sensitization in children.

The potential of anti-infectives and immunomodulators as therapies for asthma and asthma exacerbations

Asthma is responsible for approximately 25,000 deaths annually in Europe despite available medicines that maintain asthma control and reduce asthma exacerbations. Better treatments are urgently needed for the control of chronic asthma and reduction in asthma exacerbations, the major cause of asthma mortality. Much research spanning >20 years shows a strong association between microorganisms including pathogens in asthma onset, severity and exacerbation, yet with the exception of antibiotics, few treatments are available that specifically target the offending pathogens. Recent insights into the microbiome suggest that modulating commensal organisms within the gut or lung may also be a possible way to treat/prevent asthma. The European Academy of Allergy & Clinical Immunology Task Force on Anti-infectives in Asthma was initiated to investigate the potential of anti-infectives and immunomodulators in asthma. This review provides a concise summary of the current literature and aimed to identify and address key questions that concern the use of anti-infectives and both microbe- and host-based immunomodulators and their feasibility for use in asthma.

Vaccination and allergy: EAACI position paper, practical aspects

Immunization is highly effective in preventing infectious diseases and therefore an indispensable public health measure. Allergic patients deserve access to the same publicly recommended immunizations as non-allergic patients unless risks associated with vaccination outweigh the gains. Whereas the number of reported possible allergic reactions to vaccines is high, confirmed vaccine-triggered allergic reactions are rare. Anaphylaxis following vaccination is rare, affecting <1/100 000, but can occur in any patient. Some patient groups, notably those with a previous allergic reaction to a vaccine or its components, are at heightened risk of allergic reaction and require special precautions. Allergic reactions, however, may occur in patients without known risk factors and cannot be predicted by currently available tools. Unwarranted fear and uncertainty can result in incomplete vaccination coverage for children and adults with or without allergy. In addition to concerns about an allergic reaction to the vaccine itself, there is fear that routine childhood immunization may promote the development of allergic sensitization and disease. Thus, although there is no evidence that routine childhood immunization increases the risk of allergy development, such risks need to be discussed.

Vaccinations in the first year of life and risk of atopic disease - Results from the KiGGS study

BACKGROUND

The study focused on the question of whether and - if so - to what direction and extent immunisations in the 1st year may be associated with the risk of being diagnosed with atopic diseases after the 1st year of life.

METHODS

Data from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS, 2003-2006) were analysed. For analyses of potential associations between vaccination status and risk of hay fever, atopic dermatitis or asthma, sample sizes of 15254, 14297, and 15262, respectively, were available.

RESULTS

Children with a sufficient TDPHiHeP vaccination at the end of the 1st year of life had a lower risk of being diagnosed with hay fever after the 1st year of life (adjusted prevalence ratio 0.85, 95% confidence interval 0.76-0.96). Analyses for associations between TDPHiHeP vaccination and risk of atopic dermatitis or asthma, or between age at onset of vaccination or of the number of antigens vaccinated in the 1st year of life and risk of atopic disease failed to yield statistical significance.

CONCLUSIONS

Our results provide no evidence that immunisations in the 1st year of life may increase the risk of atopic disease. If any association exists at all, our results may be interpreted as weakly supportive of the hypothesis that immunisations may slightly decrease the risk of atopy in later life.

Influence of Intrinsic and Lifestyle Factors on the Development of IgE Sensitization

BACKGROUND

IgE sensitization is a prerequisite for the development of allergic symptoms. The investigation of factors influencing the development of IgE is therefore crucial for understanding the onset of allergic diseases.

METHODS

This epidemiological study investigated personal, intrinsic, and lifestyle factors in a nonselected cohort of 501 Austrian adolescents (aged 12-21 years). IgE levels to 112 allergen molecules were analyzed in the serum of participants using the ImmunoCAP ISAC®. Allergic sensitization, IgE levels to single allergens, and ISAC score sums were correlated with results obtained from a questionnaire.

RESULTS

In this adolescent cohort, male participants showed a higher sensitization frequency (56.8%) compared to females (50.9%) and significantly increased IgE levels to profilins. Underweight subjects demonstrated a stronger IgE sensitization. Family size inversely correlated with IgE levels to PR-10 allergens, and predominately paternal allergies were a predictive factor for IgE sensitization in the children. Vaccination, breastfeeding, and delivery mode showed no influence, while a highly protective effect was observed for growing up on a farm. Of all of the investigated lifestyle factors, only smoking significantly influenced the risk for IgE development. Participants with moderate frequencies of colds showed increased sensitization levels.

CONCLUSION

A hereditary predisposition and lifestyle factors such as a farming environment, smoking, family size, body weight, or frequency of colds significantly influenced the development of allergen-specific IgE in this cohort of adolescents.

Immunological considerations regarding parental concerns on pediatric immunizations

Despite the fundamental role of vaccines in the decline of infant mortality, parents may decide to decline vaccination for their own children. Many factors may influence this decision, such as the belief that the infant immune system is weakened by vaccines, and concerns have been raised about the number of vaccines and the early age at which they are administered. Studies focused on the infant immune system and its reaction to immunizations, summarized in this review, show that vaccines can overcome those suboptimal features of infant immune system that render them more at risk of infections and of their severe manifestations. In addition, many vaccines have been shown to improve heterologous innate and adaptive immunity resulting in lower mortality rates for fully vaccinated children. Thus, multiple vaccinations are necessary and not dangerous, as infants can respond to several antigens as well as when responding to single stimuli. Current immunization schedules have been developed and tested to avoid vaccine interference, improve benefits and reduce side effects compared to single administrations. The infant immune system is therefore capable, early after birth, of managing several antigenic challenges and exploits them to prompt its development.

Association between perfluoroalkyl substance exposure and asthma and allergic disease in children as modified by MMR vaccination

Perfluoroalkyl substances (PFASs) are highly persistent chemicals that might be associated with asthma and allergy, but the associations remain unclear. Therefore, this study examined whether pre- and postnatal PFAS exposure was associated with childhood asthma and allergy. Measles, mumps, and rubella (MMR) vaccination in early life may have a protective effect against asthma and allergy, and MMR vaccination is therefore taken into account when evaluating these associations. In a cohort of Faroese children whose mothers were recruited during pregnancy, serum concentrations of five PFASs - Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) - were measured at three timepoints (maternal serum in pregnancy week 34-36 and child serum at ages 5 and 13 years) and their association with immunoglobulin E (IgE) (cord blood and at age 7 years) and asthma/allergic diseases (questionnaires at ages 5 and 13 years and skin prick test at age 13 years) was determined. A total of 559 children were included in the analyses. Interactions with MMR vaccination were evaluated. Among 22 MMR-unvaccinated children, higher levels of the five PFASs at age 5 years were associated with increased odds of asthma at ages 5 and 13. The associations were reversed among MMR-vaccinated children. Prenatal PFAS exposure was not associated with childhood asthma or allergic diseases regardless of MMR vaccination status. In conclusion, PFAS exposure at age 5 was associated with increased risk of asthma among a small subgroup of MMR-unvaccinated children but not among MMR-vaccinated children. While PFAS exposure may impact immune system functions, this study suggests that MMR vaccination might be a potential effect-modifier.

Vaccines: could asthma in young children be a preventable disease? ‬‬‬‬‬‬‬

‬The long battle with asthma is far from over in developed countries. Its incidence, prevalence, and severity have been increasing for decades. By reducing the risk for asthma, significant healthcare costs can be saved. The desire to create a vaccine that might prevent asthma in young children is attractive and widely considered one of the main goals in translational asthma research. Several vaccination strategies have been tested. These include allergen-specific immunotherapy, vaccination against infectious pathogens, and modification of cell and cytokine responses. The lack of success in the prevention of asthma in young children lies on the complexity of the disease, which involves many genetic, epigenetic, and environmental interactions. This review provides a summary of current literature and aims to address key questions how to develop vaccines to prevent asthma in young children. ‬‬‬‬‬‬‬‬‬‬‬‬‬‬.

Asthma and allergy in children with and without prior measles, mumps, and rubella vaccination

BACKGROUND

The existing literature on the association between measles vaccination and subsequent risk of allergic disease is inconclusive. The aim of this study was, therefore, to determine whether measles, mumps, and rubella (MMR) vaccination administered in early childhood was associated with asthma and allergic diseases at ages 5, 7 and 13 yrs in a birth cohort.

METHODS

In the Faroe Islands, 640 children were followed from birth. Follow-up examinations at ages 5, 7 and 13 yrs included a physical examination and a maternal questionnaire about the child's health. At age 7, total and grass-specific IgE was quantified in the child's serum, and at age 13, the children underwent skin prick tests (SPT). The child's vaccination card was reviewed at examinations.

RESULTS

At age 5, 533 of 555 children had been vaccinated for MMR. After confounder adjustment, we found early life MMR vaccination to be associated with a two-third reduction in the odds of asthma (OR: 0.33, 95% CI: 0.12; 0.90) and hypersensitivity/allergy (OR: 0.32, 95% CI: 0.11; 0.88) at age 5, and the substantially decreased odds of asthma were replicated at age 13 (OR: 0.22, 95% CI: 0.08; 0.56). At age 7, serum total IgE was reduced by 62.8% (CI 95%: -84.3%; -11.9%) in the vaccinated children. MMR vaccination was not significantly associated with allergic rhinoconjuctivitis symptoms, eczema, or SPT reactions at age 13.

CONCLUSIONS

MMR vaccination early in life may have a protective effect against allergy at least up to age 7 and against asthma through age 13 yrs.

Pertussis immunization in infancy and adolescent asthma medication

BACKGROUND AND OBJECTIVES

Childhood immunization may influence the development of asthma, possibly due to lack of infections or a shift in the T-helper cell type 1/T-helper cell type 2/regulatory T cells balance. We therefore investigated whether pertussis immunization in infancy is associated with asthma medication in adolescence.

METHODS

After 14 years of no general pertussis vaccination, almost 82,000 Swedish children were immunized for pertussis in a vaccination trial between June 1, 1993, and June 30, 1994. In a follow-up analysis of almost 80,000 children, their data were compared with those of ∼100,000 nonvaccinated children, born during a 5-month period before and a 7-month period after the vaccination trial. Data for the main outcome variable (ie, dispensed prescribed asthma medication for each individual in the cohort during 2008-2010) were obtained from the national prescription database. Multivariate regression models were used to calculate the effect size of vaccination on dispensed asthma medication (odds ratios [OR], 95% confidence intervals [CI]). Approaches similar to intention-to-treat and per-protocol methods were used.

RESULTS

The prevalence rates of various asthma medications for study patients at 15 years of age differed between 4.6% and 7.0%. The crude ORs for any asthma medication and antiinflammatory treatment in pertussis-vaccinated children after intention-to-treat analysis were 0.97 (95% CI: 0.93-1.00) and 0.94 (95% CI: 0.90-0.98), respectively. Corresponding adjusted ORs were 0.99 (95% CI: 0.95-1.03) and 0.97 (95% CI: 0.92-1.01). Similar ORs were found after per-protocol analysis.

CONCLUSIONS

Pertussis immunization in infancy does not increase the risk of asthma medication use in adolescents. Our study presents evidence that pertussis immunization in early childhood can be considered safe with respect to long-term development of asthma.

Association of pertussis and measles infections and immunizations with asthma and allergic sensitization in ISAAC Phase Two

BACKGROUND

Pertussis and measles infection as well as vaccination have been suspected as possible mediating factors of allergic disease in childhood.

METHODS

Between 1995 and 2005 cross-sectional studies were performed in 29 centers in 21 countries. Parental questionnaires were used to collect information on allergic diseases and exposures. We analyzed data from 54,943 randomly selected schoolchildren aged 8-12 yr. A subgroup of 31,759 children was also skin prick tested (SPT) to common environmental allergens. Combined odds ratios were calculated by random effect models for meta-analysis.

RESULTS

Pertussis and measles vaccination were not significantly associated with any of the allergy outcomes or SPT positivity. However, pertussis infection was associated with wheeze (OR(ad) 1.68; 95% CI 1.44-1.97) and rhinoconjunctivitis (OR(ad) 1.63; 95% 1.33-2.00). Pertussis infection was also significantly associated with a higher prevalence of reported eczema during the past year in non-affluent countries. Measles infection was associated with a higher prevalence of wheeze (OR(ad) 1.26; 95% 1.10-1.43) and reported eczema (OR(ad) 1.22; 95% 1.08-1.39). No association with SPT positivity was found, suggesting that these associations are unlikely to be mediated by an allergic component.

CONCLUSIONS

Associations of pertussis and measles infection with symptoms of asthma, rhinoconjunctivitis and eczema were found in both affluent and non-affluent countries and are unlikely to be mediated by IgE.

How aluminum adjuvants could promote and enhance non-target IgE synthesis in a genetically-vulnerable sub-population

Aluminum-containing adjuvants increase the effectiveness of vaccination, but their ability to augment immune responsiveness also carries the risk of eliciting non-target responses, especially in genetically susceptible individuals. This study reviews the relevant actions of aluminum adjuvants and sources of genetic risk that can combine to adversely affect a vulnerable sub-population. Aluminum adjuvants promote oxidative stress and increase inflammasome activity, leading to the release of IL-1β, IL-18, and IL-33, but not the important regulatory cytokine IL-12. In addition, they stimulate macrophages to produce PGE₂, which also has a role in regulating immune responses. This aluminum-induced cytokine context leads to a T(H)2 immune response, characterized by the further release of IL-3, IL-4, IL-5, IL-9, IL-13, and IgE-potentiating factors such as sCD23. Genetic variants in cytokine genes, such as IL-4, IL-13, IL-33, and IL-18 influence the response to vaccines in children and are also associated with atopy. These genetic factors may therefore define a genetically-vulnerable sub-population, children with a family history of atopy, who may experience an exaggerated T(H)2 immune response to aluminum-containing vaccines. IL-4, sCD23, and IgE are common factors for both atopy and the immune-stimulating properties of aluminum adjuvants. IL-4 is critical in the production of IgE and total IgE up-regulation. IL-4 has also been reported to induce the production of sCD23 and trigger resting sIgM+, sIgD+ B-cells to switch to sIgE+ B-cells, making them targets for IgE-potentiating factors. Further, the actions of IgE-potentiating factors on sIgE+ B-cells are polyclonal and unrestricted, triggering their differentiation into IgE-forming plasma cells. These actions provide a mechanism for aluminum-adjuvant promotion and enhancement of non-target IgE in a genetically vulnerable sub-population. Identification of these individuals may decrease the risk of adverse events associated with the use of aluminum-containing vaccines.

Preventive medicines: vaccination, prophylaxis of infectious diseases, disinfectants

Immunizations belong to the most successful interventions in medicine. Like other drugs, vaccines undergo long periods of pre-clinical development, followed by careful clinical testing through study Phases I, II, and III before they receive licensure. A successful candidate vaccine will move on to be an investigational vaccine to undergo three phases of pre-licensure clinical trials in a stepwise fashion before it can be considered for approval, followed by an optional fourth phase of post-marketing assessment. The overall risk-benefit assessment of a candidate vaccine is very critical in making the licensure decision for regulatory authorities, supported by their scientific committees. It includes analyses of immunogenicity, efficacy, reactogenicity or tolerability, and safety of the vaccine. Public trust in vaccines is a key to the success of immunization programs worldwide. Maintaining this trust requires knowledge of the benefits and scientific understanding of real or perceived risks of immunizations. Under certain circumstances, pre- or post-exposure passive immunization can be achieved by administration of immunoglobulines. In terms of prevention of infectious diseases, disinfection can be applied to reduce the risk of transmission of pathogens from patient to patient, health-care workers to patients, patients to health-care workers, and objects or medical devices to patients.

Asthma prevalence and exacerbations in children: is there an association with childhood vaccination?

Infections and vaccinations may have a potential role in the normal maturation of the immune system, in the development and balance of regulatory pathways, and in the development and exacerbations of asthma. Asthma exacerbations often result from respiratory viral infections, and, while vaccination towards common viral infections may reduce the occurrence of such exacerbations, there has been concern that vaccinations can increase the risk of asthma. Current studies show that childhood vaccines, including inactivated influenza vaccine, are generally safe. However, there is some concern regarding possible exacerbations in infants or children with frequent wheezing or persistent asthma who are given live-attenuated influenza vaccination. Although severe allergic adverse events attributable to vaccination are extremely rare, all serious allergic reactions should be further assessed to detect the likely causative vaccine component, such as egg protein or gelatin. The risks of not vaccinating children far outweigh the risks of allergy and asthma exacerbations. Therefore, childhood vaccination should remain an essential part of child health programs and should not be withheld, even from children with asthma or those predisposed to allergy.

A risk-benefit analysis of vaccination

Impressive success has been achieved worldwide with population based immunisation programmes against several serious infectious diseases. This success is being threatened: the incidence of previously frequent, potentially devastating diseases decreases as a consequence of successful immunisation programmes and attention of the public shifts towards true and alleged "side effects" of vaccines. This can lead to the dilemma of waning public confidence in the necessity, tolerability and safety of vaccinations. Therefore, continuous evaluation of risks and benefits of vaccines is required and results of these need to be communicated broadly to strengthen the confidence in immunisation programmes.

An open study to assess the efficacy clinically and immunologically ofM. vaccaevaccine in patients with atopic dermatitis

OBJECTIVE

To assess clinical and immunological changes in a group of atopic dermatitis patients treated with Mycobacterium vaccae (M. vaccae).

METHODS

In an open, randomized, placebo-controlled, clinical observer-blinded trial, 20 patients with moderately severe to severe atopic dermatitis were treated with two subcutaneous M. vaccae injections 3 months apart. Clinical scoring and total serum IgE estimation were performed at the start, during and 3 months after the end of the study.

RESULTS

Modest clinical improvement was seen in the patients after M. vaccae immunotherapy. There was no significant change in patients' total serum IgE levels.

CONCLUSIONS

This study has shown limited improvement clinically in a group of patients with atopic dermatitis treated with two M. vaccae injections. It is suggested that further trials using four to six injections would produce much greater benefit.

Allergic disease and atopic sensitization in children in relation to measles vaccination and measles infection

OBJECTIVE

Our aim was to investigate the role of measles vaccination and measles infection in the development of allergic disease and atopic sensitization.

METHODS

A total of 14 893 children were included from the cross-sectional, multicenter Prevention of Allergy-Risk Factors for Sensitization in Children Related to Farming and Anthroposophic Lifestyle study, conducted in 5 European countries (Austria, Germany, the Netherlands, Sweden, and Switzerland). The children were between 5 and 13 years of age and represented farm children, Steiner-school children, and 2 reference groups. Children attending Steiner schools often have an anthroposophic (holistic) lifestyle in which some immunizations are avoided or postponed. Parental questionnaires provided information on exposure and lifestyle factors as well as symptoms and diagnoses in the children. A sample of the children was invited for additional tests, and 4049 children provided a blood sample for immunoglobulin E analyses. Only children with complete information on measles vaccination and infection were included in the analyses (84%).

RESULTS

In the whole group of children, atopic sensitization was inversely associated with measles infection, and a similar tendency was seen for measles vaccination. To reduce risks of disease-related modification of exposure, children who reported symptoms of wheezing and/or eczema debuting during first year of life were excluded from some analyses. After this exclusion, inverse associations were observed between measles infection and "any allergic symptom" and "any diagnosis of allergy by a physician." However, no associations were found between measles vaccination and allergic disease.

CONCLUSION

Our data suggest that measles infection may protect against allergic disease in children.

Routine vaccination against pertussis and the risk of childhood asthma: a population-based cohort study

BACKGROUND

In industrialized countries vaccination coverage remains suboptimal, partly because of perception of an increased risk of asthma. Epidemiologic studies of the association between childhood vaccinations and asthma have provided conflicting results, possibly for methodologic reasons such as unreliable vaccination data, biased reporting, and reverse causation. A recent review stressed the need for additional, adequately controlled large-scale studies.

OBJECTIVE

Our goal was to determine if routine childhood vaccination against pertussis was associated with subsequent development of childhood wheezing disorders and asthma in a large population-based cohort study.

METHODS

In 6811 children from the general population born between 1993 and 1997 in Leicestershire, United Kingdom, respiratory symptom data from repeated questionnaire surveys up to 2003 were linked to independently collected vaccination data from the National Health Service database. We compared incident wheeze and asthma between children of different vaccination status (complete, partial, and no vaccination against pertussis) by computing hazard ratios. Analyses were based on 6048 children, 23 201 person-years of follow-up, and 2426 cases of new-onset wheeze.

RESULTS

There was no evidence for an increased risk of wheeze or asthma in children vaccinated against pertussis compared with nonvaccinated children. Adjusted hazard ratios comparing fully and partially vaccinated with nonvaccinated children were close to one for both incident wheeze and asthma.

CONCLUSION

This study provides no evidence of an association between vaccination against pertussis in infancy and an increased risk of later wheeze or asthma and does not support claims that vaccination against pertussis might significantly increase the risk of childhood asthma.

Early atopic disease and early childhood immunization--is there a link?

BACKGROUND

There are frequent concerns about early immunizations among the parents of children at heightened risk for atopy. The study assessed the effect of vaccine immunization before the first birthday on eczema severity and allergic sensitization in the second year of life.

METHODS

A total of 2184 infants, aged 1-2 years, with established atopic dermatitis and a family history of allergy, from 97 study centres in 10 European countries, South Africa and Australia were included. Exposure to vaccines (diphtheria, tetanus, pertussis, polio, Haemophilus influenzae Type B, hepatitis B, mumps, measles, rubella, varicella, BCG, meningococci and pneumococci) and immunization dates were recorded from immunization cards. Immunoglobulin E (IgE) was determined by RAST and eczema severity was assessed by scoring atopic dermatitis (SCORAD).

RESULTS

Immunization against any target was not associated with an increased risk of allergic sensitization to food or inhalant allergens. Varicella immunization (only 0.7% immunized) was inversely associated with total IgE > 30 kU/l (OR 0.27; 95% CI 0.08-0.87) and eczema severity (OR 0.34; 95% CI 0.12-0.93). Pertussis immunization (only 1.7% nonimmunized) was inversely associated with eczema severity (OR 0.30; 95% CI 0.10-0.89). Cumulative received vaccine doses were inversely associated with eczema severity (P = 0.0107). The immunization coverage of infants before and after the onset of atopic dermatitis was similar.

CONCLUSION

In children at heightened risk for atopy, common childhood immunization in the first year is not associated with an increased risk of more severe eczema or allergic sensitization. Parents of atopic children should be encouraged to fully immunize their children.

Delay in diphtheria, pertussis, tetanus vaccination is associated with a reduced risk of childhood asthma

BACKGROUND

Early childhood immunizations have been viewed as promoters of asthma development by stimulating a T(H)2-type immune response or decreasing microbial pressure, which shifts the balance between T(H)1 and T(H)2 immunity.

OBJECTIVE

Differing time schedules for childhood immunizations may explain the discrepant findings of an association with asthma reported in observational studies. This research was undertaken to determine whether timing of diphtheria, pertussis, tetanus (DPT) immunization has an effect on the development of childhood asthma by age 7 years.

METHODS

This was a retrospective longitudinal study of a cohort of children born in Manitoba in 1995. The complete immunization and health care records of cohort children from birth until age 7 years were available for analysis. The adjusted odds ratio for asthma at age 7 years according to timing of DPT immunization was computed from multivariable logistic regression.

RESULTS

Among 11, 531 children who received at least 4 doses of DPT, the risk of asthma was reduced to (1/2) in children whose first dose of DPT was delayed by more than 2 months. The likelihood of asthma in children with delays in all 3 doses was 0.39 (95% CI, 0.18-0.86).

CONCLUSION

We found a negative association between delay in administration of the first dose of whole-cell DPT immunization in childhood and the development of asthma; the association was greater with delays in all of the first 3 doses. The mechanism for this phenomenon requires further research.

Diagnosis and treatment of asthma in childhood: a PRACTALL consensus report

Asthma is the leading chronic disease among children in most industrialized countries. However, the evidence base on specific aspects of pediatric asthma, including therapeutic strategies, is limited and no recent international guidelines have focused exclusively on pediatric asthma. As a result, the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma and Immunology nominated expert teams to find a consensus to serve as a guideline for clinical practice in Europe as well as in North America. This consensus report recommends strategies that include pharmacological treatment, allergen and trigger avoidance and asthma education. The report is part of the PRACTALL initiative, which is endorsed by both academies.

Is childhood vaccination associated with asthma? A meta-analysis of observational studies

BACKGROUND

The possible link between immunization and atopic diseases has been under intense debate in the last decade.

OBJECTIVE

The aim of this study was to systematically review the available evidence on the association of whole-cell pertussis and BCG vaccination with the risk of asthma in childhood and adolescence.

METHODS

The major medical electronic databases (Medline, National Library of Medicine Gateway, and Cochrane Library) were searched, and reference lists of the relevant publications were reviewed for relevant birth-cohort studies and randomized, controlled trials from 1966 to March 2006. Only studies that directly compared vaccinated and unvaccinated children, validated vaccination status by medical charts, and used preset criteria to define asthma were included. Data were abstracted by using a standardized protocol and computerized report form. Results were analyzed by applying a fixed-effect or random-effect model, according to the heterogeneity of the studies. Sensitivity analyses by scoring criteria were performed.

RESULTS

Seven studies of pertussis vaccination (with a total of 186,663 patients) and 5 studies of BCG vaccination (with a total of 41,479 patients) met our inclusion criteria. No statistically significant association was detected between either whole-cell pertussis or BCG vaccination and incidence rates of asthma during childhood and adolescence. This lack of a significant association proved to be robust on sensitivity analyses for BCG but not for pertussis vaccine.

CONCLUSIONS

Currently available data, based on observational studies, do not support an association, provocative or protective, between receipt of the BCG or whole-cell pertussis vaccine and risk of asthma in childhood and adolescence.

The complex link between immunization against childhood diseases and allergy

Vaccines can be at the origin of allergic manifestations in susceptible children. Such manifestations include: immediate-type hypersensitivity (anaphylactic shock, rash or angioedema) within 1 h after the injection; semi-late hypersensitivity (local inflammatory lesion such as the Arthus phenomenon) a few hours after the injection; and delayed-type hypersensitivity (abscess or eczema at the site of the injection). Furthermore, early-life vaccinations have been implicated in the modulation of the immune system as they could promote the development of allergy by avoiding infections. However, most population-based studies have not found an increased risk of allergies in vaccinated children. Due to methodological problems in conducting the studies, further investigations are needed to better understand the phenomenon.

Diphtheria, pertussis, poliomyelitis, tetanus, and Haemophilus influenzae type b vaccinations and risk of eczema and recurrent wheeze in the first year of life: the KOALA Birth Cohort Study

OBJECTIVES

Among potential etiologic factors for atopic manifestations, infant vaccinations have recently been discussed. We evaluated in a prospective design whether infants who were unvaccinated or vaccinated according to incomplete vaccination schedules in the first 6 months of age were at decreased risk for eczema and recurrent wheeze in the first year of life.

METHODS

Information on vaccinations against diphtheria, pertussis, poliomyelitis, tetanus; Haemophilus influenzae type b vaccine; and eczema and recurrent wheeze was collected by repeated questionnaires in 2764 families participating in the KOALA Birth Cohort Study in The Netherlands. A standard vaccination schedule referred to 3 diphtheria, pertussis, poliomyelitis, tetanus, and Haemophilus influenzae type b vaccinations in the first 6 months with the first given in months 1 to 3; an incomplete vaccination schedule was defined as any other vaccination schedule. Exclusion criteria were prematurity (gestational age <37 weeks) and congenital abnormalities related to immunity (such as Down syndrome). Multiple logistic regression models were fitted to adjust for confounding factors.

RESULTS

During the first year of life, the incidence of eczema was 23% (584 of 2537 infants) and of recurrent wheeze, the incidence was 8.5% (203 of 2402 infants). At age 6 months, 1969 (77%) of 2545 infants had been vaccinated according to a standard schedule, 393 (15%) vaccinated according to an incomplete schedule, and 182 (7%) never vaccinated. Compared with infants with standard vaccination schedules, infants with incomplete schedules did not differ significantly in eczema risk or recurrent wheeze. This was also true for infants who had never been vaccinated.

CONCLUSION

This study shows that the risk of eczema or recurrent wheeze at 1 year of age does not differ between infants with different vaccination status at the age of 6 months.

Do vaccines modify the prevalence of asthma and allergies?

Epidemiological studies suggest the hypothesis that the increase in asthma and allergies in the industrialized world can be explained by a decline in the number of infectious diseases occurring during childhood. In the context of this 'hygiene hypothesis', is immunization in early life a risk factor for promoting allergic diseases? The majority of studies, especially those conducted with more extensive populations, have not found an increased risk, and although 'not finding an increased risk' is not the same as 'the non-existence of any risk at all', it seems that the evidence is tipped in favor of the absence of risk. Conversely, although some surveys have described a protective effect of vaccination, the majority refuted this result. If there is any effect, it is probably a weak one.

Is childhood immunisation associated with atopic disease from age 7 to 32 years?

BACKGROUND

There is ongoing conjecture over whether childhood immunisation leads to an increased risk of developing atopic diseases.

OBJECTIVE

To examine associations between childhood immunisation and the risk of atopic disease.

METHOD

Immunisation histories of 8443 Tasmanian children born in 1961 obtained from school medical records were linked to the Tasmanian Asthma Study. Associations between immunisation status and atopic diseases were examined while adjusting for possible confounders using multiple logistic regression.

RESULTS

Diphtheria immunisation was weakly associated with an increased risk of asthma by age 7 years (odds ratio (OR) 1.3, 95% confidence interval (CI) 1.1 to 1.7), but there was no evidence of any association for four other vaccinations studied. An increased risk of eczema by age 7 years was associated with immunisation against diphtheria (OR 1.5, 95% CI 1.1 to 2.1), tetanus (OR 1.5, 95% CI, 1.1 to 2.0), pertussis (OR 1.5, 95% CI 1.1 to 1.9) and polio (OR 1.4, 95% CI 1.0 to 1.9) but not small pox. Similar but slightly weaker patterns of association were observed between the risk of food allergies and immunisation against diphtheria (OR 1.5, 95% CI 1.0 to 2.1), pertussis (OR 1.4, 95% CI 1.1 to 1.9), polio (OR 1.4, 95% CI 1.00 to 2.1) and tetanus (OR 1.30 95% CI 0.99 to 1.70), but not with small pox. There was no evidence of associations between immunisation history and hay fever, or incidence of later-onset atopic outcomes.

CONCLUSIONS

The few effects seen in this study are small and age-dependent, and nearly all our findings support numerous previous studies of no effect of vaccines on asthma. Based on these findings, the fear of their child developing atopic disease should not deter parents from immunising their children, especially when weighed against the benefits.

Common vaccine antigens inhibit allergen-induced sensitization and airway hyperresponsiveness in a murine model

BACKGROUND

Co-vaccination with cellular pertussis vaccine down-regulates allergic sensitization to diphtheria and tetanus antigens. Using a murine model, we investigated whether vaccination with diphtheria/tetanus toxoids, administered separately or simultaneously with the whole cell vaccine of Bordetella pertussis, inhibits subsequent allergen-induced immune and inflammatory responses.

METHODS

BALB/c-mice were vaccinated intracutaneously with a combination of diphtheria and tetanus toxoids or a combination of diphtheria and tetanus toxoids with a whole cell vaccine of B. pertussis (three times, days -21 to -7) prior to systemic sensitization (days 1-14) and repeated airway challenges (days 28-30) with ovalbumin.

RESULTS

Compared with negative controls, systemic sensitization and airway allergen challenges induced high serum levels of allergen-specific IgE, predominant Th2-type cytokine production, airway inflammation and development of in vivo airway hyperreactivity. Vaccination with diphtheria and tetanus toxoids prior to sensitization suppressed IgE formation and development of eosinophilic airway inflammation. Co-vaccination with a whole cell pertussis vaccine inhibited allergen sensitization, airway inflammation and development of in vivo airway hyperreactivity. Prevention was due to an allergen-specific and general shift from a predominant Th2 towards a predominant Th1 immune response.

CONCLUSION

Vaccination with diphtheria and tetanus toxoids alone or in combination with whole cell pertussis vaccine prior to allergen sensitization prevented allergen-induced Th2 immune responses. Vaccine antigens may down-regulate allergic responses to a range of common allergens.

Fever, use of antibiotics, and acute gastroenteritis during infancy as risk factors for the development of asthma in Korean school-age children

OBJECTIVE

The hygiene hypothesis postulates that infections early in life might influence the development of asthma later in childhood. However, this hypothesis is controversial. The objective of this study was to determine whether there is a relationship between infection-related risk factors during infancy and development of asthma later in childhood.

METHODS

Data were obtained by a nationwide, population-based, cross-sectional study of 26,400 children, 7 to 12 years of age. Parents completed a questionnaire on symptoms of and risk factors for asthma, including the number of fever episodes, acute gastroenteritis, use of antibiotics, and immunization during infancy. The presence of asthma was defined by parental report of "wheeze in the last 12 months" or "asthma ever." Data were analyzed by logistic regression analysis.

RESULTS

The occurrence of fever during infancy was weakly associated with the development of asthma (P < 0.05). A higher frequency of episodes of fever was associated with a higher risk of development of asthma. The relationship between antibiotic use during infancy and development of asthma was also significant (P < 0.0001). The adjusted odds ratios of childhood asthma increased in proportion to the number of antibiotic courses during infancy. A history of acute gastroenteritis during infancy increased the risk of developing asthma in later life (P < 0.001). In contrast, immunization in infancy was not related to development of asthma in childhood (P > 0.05).

CONCLUSIONS

These data suggest that the development of childhood asthma is associated with episodes of fever, antibiotic use, and acute gastroenteritis during infancy.

Acellular pertussis vaccine protects against exacerbation of allergic asthma due to Bordetella pertussis in a murine model

The prevalence of asthma and allergic disease has increased in many countries, and there has been speculation that immunization promotes allergic sensitization. Bordetella pertussis infection exacerbates allergic asthmatic responses. We investigated whether acellular pertussis vaccine (Pa) enhanced or prevented B. pertussis-induced exacerbation of allergic asthma. Groups of mice were immunized with Pa, infected with B. pertussis, and/or sensitized to ovalbumin. Immunological, pathological, and physiological changes were measured to assess the impact of immunization on immune deviation and airway function. We demonstrate that immunization did not enhance ovalbumin-specific serum immunoglobulin E production. Histopathological examination revealed that immunization reduced the severity of airway pathology associated with sensitization in the context of infection and decreased bronchial hyperreactivity upon methacholine exposure of infected and sensitized mice. These data demonstrate unequivocally the benefit of Pa immunization to health and justify selection of Pa in mass vaccination protocols. In the absence of infection, the Pa used in this study enhanced the interleukin-10 (IL-10) and IL-13 responses and influenced airway hyperresponsiveness to sensitizing antigen; however, these data do not suggest that Pa contributes to childhood asthma overall. On the contrary, wild-type virulent B. pertussis is still circulating in most countries, and our data suggest that the major influence of Pa is to protect against the powerful exacerbation of asthma-like pathology induced by B. pertussis.

The influence of childhood infections and vaccination on the development of atopy: A systematic review of the direct epidemiological evidence

BACKGROUND

The 'hygiene hypothesis' has been used to justify a belief common among homeopaths, that the suppression of childhood infections and immunisation may lead to the development of chronic atopic diseases.

OBJECTIVES

To analyse the influence of childhood infections and immunisation on the development of atopy.

METHODS

Qualitative systematic review of direct epidemiological evidence (Medline 1993-2004) concerning the influence of childhood infections and immunisation on the development of atopy and discussion based on homeopathy.

CONCLUSIONS

(1) Childhood infections do not protect against atopy; on the contrary, they increase the risk of allergic diseases, in agreement to Hahnemann's observations, which included epidemic diseases among the factors capable of stimulating the development of chronic diseases. (2) Vaccination is not a risk factor for atopy, notwithstanding the allergenic effect of some vaccines.

Whole-cell pertussis vaccine protects against Bordetella pertussis exacerbation of allergic asthma

The prevalence of asthma and allergic disease has increased in many countries and there has been speculation that immunization promotes allergic sensitization. Bordetella pertussis infection exacerbates allergic asthmatic responses. We investigated whether whole-cell pertussis vaccine (Pw) enhanced or prevented B. pertussis induced exacerbation of allergic asthma. Groups of mice were immunized with Pw, infected with B. pertussis and/or sensitized to ovalbumin. Immunological, pathological and physiological changes were measured to assess the impact of Pw immunization on immune deviation and airway function. Pw immunization modulated ovalbumin-specific serum IgE production, and reduced local and systemic IL-13 and other cytokine responses to sensitizing allergen. Histopathological examination revealed Pw immunization reduced the severity of airway pathology and decreased bronchial hyperreactivity to methacholine exposure. Pw does not enhance airway IL-13 and consequently does not enhance but protects against the exacerbation of allergic responses. We find no evidence of Pw contributing to allergic asthma, but rather provide evidence of a mechanism whereby whole-cell pertussis vaccination has a protective role.

Timing of routine immunisations and subsequent hay fever risk

BACKGROUND

Suggestions that immunisation influences allergic disease risk, either positively (pertussis) or negatively (BCG) are of concern for vaccination policy.

AIMS

To determine whether DTP, MMR, and BCG vaccination in infancy influenced hay fever risk.

METHODS

Case-control study of 7098 hay fever cases and controls, within two primary care databases. One control per case was matched for practice, age, and sex. Odds ratios (OR) were derived using conditional logistic regression.

RESULTS

Compared to those completing in month 5 (base group) (39.3%), DTP unvaccinated children (4.3%) had a similar risk of hay fever (OR = 0.94, 95% CI 0.73 to 1.23). However, those completing after 12 months (4.2%) had a reduced risk (OR = 0.60, 95% CI 0.45 to 0.76) compared to the base group. Compared to those vaccinated in month 14 (base group) (29.5%), MMR unvaccinated children (2.3%) had an OR of 0.79 (95% CI 0.58 to 1.08). Completion of MMR after two years was associated with reduced hay fever risk (OR = 0.62, 95% CI 0.48 to 0.80) compared to the base group. The effects of late immunisation with DTP and MMR were independent. Those vaccinated with BCG by age 2 (2.4%) had an odds ratio of 1.28 (95% CI 0.96 to 1.70). Adjustment for consulting behaviour, social factors, or sibship size did not alter these associations.

CONCLUSIONS

Immunisation against DTP or MMR does not increase the risk of hay fever. The lower confidence limit for BCG vaccination contradicts the hypothesised protective effect. The reduced risk of hay fever among children immunised late may be explained by a third factor causing both postponement and reduced risk such as intercurrent febrile illnesses.

The relationship between vaccine refusal and self-report of atopic disease in children

BACKGROUND

In the last 3 decades, there has been an unexplained increase in the prevalence of asthma and hay fever.

OBJECTIVE

We sought to determine whether there is an association between childhood vaccination and atopic diseases, and we assessed the self-reported prevalence of atopic diseases in a population that included a large number of families not vaccinating their children.

METHODS

Surveys were mailed to 2964 member households of the National Vaccine Information Center, which represents people concerned about vaccine safety, to ascertain vaccination and atopic disease status.

RESULTS

The data included 515 never vaccinated, 423 partially vaccinated, and 239 completely vaccinated children. In multiple regression analyses there were significant ( P < .0005) and dose-dependent negative relationships between vaccination refusal and self-reported asthma or hay fever only in children with no family history of the condition and, for asthma, in children with no exposure to antibiotics during infancy. Vaccination refusal was also significantly ( P < .005) and negatively associated with self-reported eczema and current wheeze. A sensitivity analysis indicated that substantial biases would be required to overturn the observed associations.

CONCLUSION

Parents who refuse vaccinations reported less asthma and allergies in their unvaccinated children. Although this relationship was independent of measured confounders, it could be due to differences in other unmeasured lifestyle factors or systematic bias. Further research is needed to verify these results and investigate which exposures are driving the associations between vaccination refusal and allergic disease. The known benefits of vaccination currently outweigh the unproved risk of allergic disease.

Does childhood immunization against infectious diseases protect from the development of atopic disease?

The argument of whether early immunization against infections promotes allergy or protects from it is presently under debate. The relationship between childhood immunization and the development of atopic diseases (asthma, allergic rhinitis and eczema) was examined in a population-based sample of 718 adolescents by taking individual data drawn from personal paediatric records on the schedule and the type of vaccination into account. Atopic diseases were determined using a standardized questionnaire. After adjustment for sex, age, father's socioeconomic status and active smoking, adolescents having been vaccinated (n = 694) had a significant lower risk to suffer from asthma or atopic diseases than non-vaccinated adolescents did (n = 24) [odds ratio (OR) = 0.30; 95% CI: 0.10, 0.92]. The relationship did not depend on the disease against which the vaccine was used as prophylaxis, the observance of the vaccination schedule or the number of inoculations. A higher protection was observed in the case of live attenuated vaccines (oral poliomyelitis and bacilli Camille-Guerin; OR = 0.26; 95% CI: 0.08, 0.83). These results, in agreement with previous ecological data, support the hypothesis that early vaccines could promote Th1 proliferation in response to the infectious agent contained in it, which inhibits the enhancement of atopic manifestations. Further studies are needed to confirm the phenomenon.