Neonatal BCG has no effect on allergic sensitization and suspected food allergy until 13 months

Neonatal BCG Vaccination for Prevention of Allergy in Infants: The MIS BAIR Randomised Controlled Trial

BACKGROUND

The beneficial off-target effects of Bacille Calmette-Guérin (BCG) vaccination potentially include protection against allergy.

OBJECTIVE

In the MIS BAIR trial, we aimed to determine whether neonatal BCG vaccination reduces atopic sensitisation and clinical food allergy in infants.

METHODS

In this randomised controlled trial, 1272 neonates were allocated to BCG-Denmark vaccine (0.05 mL intradermal dose) or no BCG at birth. Randomisation was stratified by recruitment site, mode of delivery and plurality of birth. The primary outcome was the incidence of atopic sensitisation determined by skin prick test at 1 year of age. Food allergy was determined by 3-monthly online questionnaires and oral food challenges. Data were analysed by intention-to-treat using binary regression.

CLINICALTRIALS

gov (NCT01906853).

RESULTS

Atopic sensitisation during the first year of life was 22.9% among infants in the BCG group and 18.9% in the control group (adjusted risk difference (aRD) 3.8% (95% CI -1.5 to 9.1) after multiple imputation). Clinical food allergy was similar between infants in the BCG and control groups (9.8% vs. 9.6%; aRD 0.2, 95% CI -3.4 to 3.8). An interaction was observed between the primary outcome and maternal history of BCG vaccination. No interaction was observed for the additional prespecified potential effect modifiers tested (sex, delivery mode, family history of any allergy, season of birth, hepatitis B vaccination at randomisation, BCG scar and age at BCG administration).

CONCLUSIONS AND CLINICAL RELEVANCE

Neonatal BCG-Denmark vaccination does not protect against atopic sensitisation or clinical food allergy in the first year of life.

Trained innate immunity, epigenetics, and food allergy

In recent years the increased incidence of food allergy in Western culture has been associated with environmental factors and an inappropriate immune phenotype. While the adaptive immune changes in food allergy development and progression have been well-characterized, an increase in innate cell frequency and activation status has also recently received greater attention. Early in prenatal and neonatal development of human immunity there is a reliance on epigenetic and metabolic changes that stem from environmental factors, which are critical in training the immune outcomes. In the present review, we discuss how trained immunity is regulated by epigenetic, microbial and metabolic factors, and how these factors and their impact on innate immunity have been linked to the development of food allergy. We further summarize current efforts to use probiotics as a potential therapeutic approach to reverse the epigenetic and metabolic signatures and prevent the development of severe anaphylactic food allergy, as well as the potential use of trained immunity as a diagnostic and management strategy. Finally, trained immunity is presented as one of the mechanisms of action of allergen-specific immunotherapy to promote tolerogenic responses in allergic individuals.

Maintaining a 'fit' immune system: the role of vaccines

INTRODUCTION

Conventionally, vaccines are thought to induce a specific immune response directed against a target pathogen. Long recognized but poorly understood nonspecific benefits of vaccination, such as reduced susceptibility to unrelated diseases or cancer, are now being investigated and may be due in part to "trained immunity'.

AREAS COVERED

We discuss 'trained immunity' and whether vaccine-induced 'trained immunity' could be leveraged to prevent morbidity due to a broader range of causes.

EXPERT OPINION

The prevention of infection i.e. maintaining homeostasis by preventing the primary infection and resulting secondary illnesses, is the pivotal strategy used to direct vaccine design and may have long-term, positive impacts on health at all ages. In the future, we anticipate that vaccine design will change to not only prevent the target infection (or related infections) but to generate positive modifications to the immune response that could prevent a wider range of infections and potentially reduce the impact of immunological changes associated with aging. Despite changing demographics, adult vaccination has not always been prioritized. However, the SARS-CoV-2 pandemic has demonstrated that adult vaccination can flourish given the right circumstances, demonstrating that harnessing the potential benefits of life-course vaccination is achievable for all.

Efficacy and Safety of BCG Revaccination With M. bovis BCG Moscow to Prevent COVID-19 Infection in Health Care Workers: A Randomized Phase II Clinical Trial

The Bacillus Calmette-Guérin (BCG) vaccine, which is widely used to protect children against tuberculosis, can also improve immune response against viral infections. This unicentric, randomized-controlled clinical trial assessed the efficacy and safety of revaccination with BCG Moscow in reducing the positivity and symptoms of COVID-19 in health care workers (HCWs) during the COVID-19 pandemic. HCWs who had negative COVID-19 IgM and IgG and who dedicated at least eight hours per week in facilities that attended to individuals suspected of having COVID-19 were included in the study and were followed for 7, 15, 30, 60, and 180 days by telemedicine. The HCWs were randomly allocated to a revaccinated with BCG group, which received the BCG vaccine, or an unvaccinated group. Revaccination with BCG Moscow was found to be safe, and its efficacy ranged from 30.0% (95.0%CI -78.0 to 72.0%) to 31.0% (95.0%CI -74.0 to 74.0%). Mycobacterium bovis BCG Moscow did not induce NK cell activation at 15–20 days post-revaccination. As hypothesized, revaccination with BCG Moscow was associated with a lower incidence of COVID-19 positivity, though the results did not reach statistical significance. Further studies should be carried out to assess whether revaccination with BCG is able to protect HCWs against COVID-19. The protocol of this clinical trial was registered on August 5th, 2020, at REBEC (Registro Brasileiro de Ensaios Clínicos, RBR-4kjqtg - ensaiosclinicos.gov.br/rg/RBR-4kjqtg/1) and the WHO (# U1111-1256-3892). The clinical trial protocol was approved by the Comissão Nacional de ética de pesquisa- CONEP (CAAE 31783720.0.0000.5078).

Prevention of infant eczema by neonatal Bacillus Calmette-Guérin vaccination: The MIS BAIR randomized controlled trial

BACKGROUND

Bacille Calmette-Guérin (BCG) vaccine could play a role in counteracting the rising prevalence of atopic diseases, through its beneficial off-target effects. We aimed to determine whether neonatal BCG vaccination reduces the incidence of eczema in infants.

METHODS

Randomized controlled trial with 1272 infants allocated to receive BCG-Denmark or no BCG at birth. The primary outcome was the 12-month incidence of eczema based on 3-monthly questionnaires. Eczema was also assessed at a 12-month clinic visit. ClinicalTrial.gov: NCT01906853.

RESULTS

The 12-month eczema incidence was 32.2% in the BCG group compared with 36.6% in the control group (adjusted risk difference (aRD) -4.3%, 95% CI -9.9% to 1.3%, multiple imputation model). In addition, comparing infants in the BCG group with the control group, 15.7% vs. 19.2% had eczema lesions at the 12-month visit (aRD -3.5%, 95% CI -8.0% to 1.0%); 35.7% vs. 39.0% reported using topical steroids (aRD -3.3, 95% CI -9.2 to 2.7); and 7.3% vs. 10.2% had severe eczema scores (aRD -3.0%, 95% CI -8.8% to 2.7%). In 344 high-risk infants (two atopic parents), the 12-month eczema incidence was 35.3% in the BCG group compared with 46.8% in the control group (aRD -11.5%, 95% CI -21.9% to -1.2%; number needed to treat 8.7, 95% CI 4.6 to 83.3).

CONCLUSION

There is insufficient evidence to recommend neonatal BCG vaccination in all infants for the prevention of eczema in the first year of life; however, a modest beneficial effect was observed among high-risk infants. A single dose of BCG-Denmark soon after birth could reduce the incidence of eczema in infants with two atopic parents.

BCG for the prevention and treatment of allergic asthma

Allergic diseases, in particular atopic asthma, have been on the rise in most industrialized countries for several decades now. Allergic asthma is characterized by airway narrowing, bronchial hyperresponsiveness, excessive airway mucus production, eosinophil influx in the lungs and an imbalance of the Th1/Th2 responses, including elevated IgE levels. Most available interventions provide only short-term relief from disease symptoms and do not alter the underlying immune imbalance. A number of studies, mostly in mouse models, have shown that Mycobacterium bovis bacillus Calmette-Guérin (BCG) treatment is capable of preventing or reducing an established allergen-driven inflammatory response, by redirecting pathogenic Th2 towards protective Th1 and/or regulatory T cell responses. Dendritic cells stimulated by BCG appear to be a crucial first step in the immunomodulatory effects of BCG. While the protective and therapeutic effects of BCG against allergy and asthma are well documented in animal models, they are less clear in humans, both in observational studies and in randomized controlled trials. The purpose of this article is to provide an up-to-date overview of the available evidence on the anti-allergy, in particular anti-asthma effects of BCG in mice, rats and humans.

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.

EAACI guideline: Preventing the development of food allergy in infants and young children (2020 update)

BACKGROUND

This guideline from the European Academy of Allergy and Clinical Immunology (EAACI) recommends approaches to prevent the development of immediate-onset / IgE-mediated food allergy in infants and young children. It is an update of a 2014 EAACI guideline.

METHODS

The guideline was developed using the AGREE II framework and the GRADE approach. An international Task Force with representatives from 11 countries and different disciplinary and clinical backgrounds systematically reviewed research and considered expert opinion. Recommendations were created by weighing up benefits and harms, considering the certainty of evidence and examining values, preferences and resource implications. The guideline was peer-reviewed by external experts, and feedback was incorporated from public consultation.

RESULTS

All of the recommendations about preventing food allergy relate to infants (up to 1 year) and young children (up to 5 years), regardless of risk of allergy. There was insufficient evidence about preventing food allergy in other age groups. The EAACI Task Force suggests avoiding the use of regular cow's milk formula as supplementary feed for breastfed infants in the first week of life. The EAACI Task Force suggests introducing well-cooked, but not raw egg or uncooked pasteurized, egg into the infant diet as part of complementary feeding. In populations where there is a high prevalence of peanut allergy, the EAACI Task Force suggests introducing peanuts in an age-appropriate form as part of complementary feeding. According to the studies, it appears that the most effective age to introduce egg and peanut is from four to 6 months of life. The EAACI Task Force suggests against the following for preventing food allergy: (i) avoiding dietary food allergens during pregnancy or breastfeeding; and (ii) using soy protein formula in the first 6 months of life as a means of preventing food allergy. There is no recommendation for or against the following: use of vitamin supplements, fish oil, prebiotics, probiotics or synbiotics in pregnancy, when breastfeeding or in infancy; altering the duration of exclusive breastfeeding; and hydrolysed infant formulas, regular cow's milk-based infant formula after a week of age or use of emollients.

CONCLUSIONS

Key changes from the 2014 guideline include suggesting (i) the introduction of peanut and well-cooked egg as part of complementary feeding (moderate certainty of evidence) and (ii) avoiding supplementation with regular cow's milk formula in the first week of life (low certainty of evidence). There remains uncertainty in how to prevent food allergy, and further well-powered, multinational research using robust diagnostic criteria is needed.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

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.

BCG vaccination in humans inhibits systemic inflammation in a sex-dependent manner

BACKGROUNDInduction of innate immune memory, also termed trained immunity, by the antituberculosis vaccine bacillus Calmette-Guérin (BCG) contributes to protection against heterologous infections. However, the overall impact of BCG vaccination on the inflammatory status of an individual is not known; while induction of trained immunity may suggest increased inflammation, BCG vaccination has been epidemiologically associated with a reduced incidence of inflammatory and allergic diseases.METHODSWe investigated the impact of BCG (BCG-Bulgaria, InterVax) vaccination on systemic inflammation in a cohort of 303 healthy volunteers, as well as the effect of the inflammatory status on the response to vaccination. A targeted proteome platform was used to measure circulating inflammatory proteins before and after BCG vaccination, while ex vivo Mycobacterium tuberculosis- and Staphylococcus aureus-induced cytokine responses in peripheral blood mononuclear cells were used to assess trained immunity.RESULTSWhile BCG vaccination enhanced cytokine responses to restimulation, it reduced systemic inflammation. This effect was validated in 3 smaller cohorts, and was much stronger in men than in women. In addition, baseline circulating inflammatory markers were associated with ex vivo cytokine responses (trained immunity) after BCG vaccination.CONCLUSIONThe capacity of BCG to enhance microbial responsiveness while dampening systemic inflammation should be further explored for potential therapeutic applications.FUNDINGNetherlands Organization for Scientific Research, European Research Council, and the Danish National Research Foundation.

Determinants of Bacille Calmette-Guérin scarification in Danish children

Background

Studies in low-income countries have shown that among Bacille Calmette-Guérin (BCG) vaccinated children, those who develop a BCG-scar have significantly better survival than those who do not develop a scar. In a Danish multicenter randomized clinical trial we assessed determinants for developing a BCG-scar and for BCG scar size following neonatal BCG vaccination.

Methods

At three Danish hospitals, newborns were randomized 1:1 to BCG vaccination or no BCG vaccination. The infants were invited for a clinical examination at the ages of 3 and 13 months. At 13 months, the scar site was inspected and scar size measured. We investigated three groups of determinants; external, parental, and individual-level determinants on relative scar prevalence and differences in median scar sizes.

Results

Among 2118 BCG vaccinated infants, 2039 (96 %) were examined at 13 months; 1857 of these (91 %) had developed a BCG-scar. Compared with Copenhagen University Hospital, Hvidovre (85 %), Copenhagen University Hospital, Rigshospitalet had a scar prevalence of 95 % (adjusted Prevalence ratio (aPR) = 1.24 [CI 95 %: 1.18 to 1.30]); it was 93 % at Kolding Hospital (aPR 1.27 [CI 95 %: 1.19 to 1.35]). Increasing vaccine experience was positively associated with developing a scar and with scar size.

Conclusion

Across multiple potential determinants of BCG scaring and size, logistical factors dominated. The results support that injection technique is an important determinant of developing a scar. Given the strong link between having a BCG scar and subsequent health, improved BCG vaccination technique could play a major role for child health.

Preventing food allergy in infancy and childhood: Systematic review of randomised controlled trials

BACKGROUND

This systematic review of ways to prevent immediate-onset/IgE-mediated food allergy will inform guidelines by the European Academy of Allergy and Immunology (EAACI).

METHODS

The GRADE approach was used. Eleven databases were searched from 1946 to October 2019 for randomized controlled trials (and large prospective cohort studies in the case of breastfeeding). The studies included heterogeneous interventions, populations, and outcomes and so were summarized narratively.

RESULTS

Forty-six studies examined interventions to reduce the risk of food allergy in infancy (up to 1 year) or early childhood. The following interventions for pregnant or breastfeeding women and/or infants may have little to no effect on preventing food allergy, but the evidence is very uncertain: dietary avoidance of food allergens, vitamin supplements, fish oil, probiotics, prebiotics, synbiotics, and emollients. Breastfeeding, hydrolyzed formulas, and avoiding cow's milk formula may not reduce the risk of cow's milk protein allergy; however, temporary supplementation with cow's milk formula in the first week of life may increase the risk of cow's milk allergy. Introducing well-cooked egg, but not pasteurized raw egg, from 4 to 6 months probably reduces the risk of hen's egg allergy. Introducing regular peanut consumption into the diet of an infant at increased risk beginning from 4 to 11 months probably results in a large reduction in peanut allergy in countries with a high prevalence. These conclusions about introducing peanut are based on moderate certainty evidence, from single trials in high-income countries.

CONCLUSIONS

Sixty percent of the included studies were published in the last 10 years, but much still remains to be understood about preventing food allergy. In particular, there is a need to validate the potential benefits of early introduction of food allergens in a wider range of populations.

A Potential Role for Epigenetically Mediated Trained Immunity in Food Allergy

The prevalence of IgE-mediated food allergy is increasing at a rapid pace in many countries. The association of high food allergy rates with Westernized lifestyles suggests the role of gene-environment interactions, potentially underpinned by epigenetic variation, in mediating this process. Recent studies have implicated innate immune system dysfunction in the development and persistence of food allergy. These responses are characterized by increased circulating frequency of innate immune cells and heightened inflammatory responses to bacterial stimulation in food allergic patients. These signatures mirror those described in trained immunity, whereby innate immune cells retain a “memory” of earlier microbial encounters, thus influencing subsequent immune responses. Here, we propose that a robust multi-omics approach that integrates immunological, transcriptomic, and epigenomic datasets, combined with well-phenotyped and longitudinal food allergy cohorts, can inform the potential role of trained immunity in food allergy.

Allergic sensitization among Danish infants at 13 months of age

Background

Sensitization means elevated number of specific immunoglobulin E, either measured by skin prick test or in blood samples. Sensitization is associated with, but not synonymous with, allergic disease.

Methods

The Danish Calmette Study was conducted from 2012 to 2015 at three Danish hospitals, with the aim of exploring nonspecific effects of neonatal Bacillus Calmette‐Guérin vaccination. Participants at Kolding Hospital were invited to have a blood sample analyzed for allergic sensitization at 13 months of age. Telephone interviews gave information about allergic symptoms, and the children were examined for signs of atopic dermatitis at 3 and 13 months.

Results

Of the 1241 children included in the Danish Calmette Study in Kolding 1066 (86%) had a blood sample drawn, representing 36% of the invited families. The blood sample cohort had a relatively high percentage of atopic predisposition (66.6%) and most mothers had a medium or long education. We found 90 infants (8.4%) to be sensitized, with sensitization against food items (milk, egg, peanut, and hazelnut) being the most common. Atopic dermatitis was found in 19% of the children, and it was significantly associated with sensitization against egg, peanut, wheat, cat, and dog.

Conclusion

In a partly selected Danish cohort, sensitization was present in 8% at 13 months of age, especially sensitization against food items. Children with atopic dermatitis were significantly more sensitized (16.6%). However, most sensitized children did not have any allergic symptoms at this age.

Immune components of early breastmilk: Association with maternal factors and with reported food allergy in childhood

BACKGROUND

Breastmilk (BM) may participate in driving gut barrier function and immunity in the neonate. We analyzed immune and growth factor concentrations in early BM and their association with maternal/environmental characteristics and with food allergy (FA) in childhood.

METHODS

One BM sample was collected in maternity from some mothers in the EDEN birth cohort (n = 2002 mother-child dyads). A random selection was performed among available samples (subcohort, n = 272), for which all deliveries were full-term, various maternal/environmental characteristics were recorded, and parents answered yearly the question "Has a medical doctor diagnosed a FA in your child?" (26 parent-reported FA cases). Only samples collected between day 2 and day 6 post-partum were considered for descriptive analysis (n = 263). Samples for all other FA cases available were added to the subcohort (46 additional cases; "casecohort" design). Fifty cytokines, antibodies, and growth factor concentrations were determined using multiplexed kits and analyzed using robust statistical procedures.

RESULTS

BM components exhibited wide concentration ranges and global day-to-day variation. Different clusters of correlated factors appeared, with components from the main cluster related to maternal diet during pregnancy. Primiparity was positively associated with eleven other components, whereas other factors (eg, maternal atopy and smoking) were related to fewer components. Finally, the casecohort design highlighted a positive association between CXCL10, TNFβ, and IL-2 concentrations and reported FA in childhood.

CONCLUSION

Beyond the unique description of early BM composition, we show that immune information transmitted to the neonate is related to various maternal factors and identified components associated with FA diagnosis in childhood.

Non-specific effects of vaccines: Current evidence and potential implications

Besides protection against specific microorganisms, vaccines can induce heterologous or non-specific effects (NSE). Epidemiological data suggest that vaccination with live-attenuated vaccines such as Bacillus Calmette-Guérin (BCG), measles vaccine, and oral polio vaccine results in increased overall childhood survival, and several of these observations have been confirmed in randomized trials. Immunological mechanisms mediating NSE include heterologous lymphocyte effects and induction of innate immune memory (trained immunity). Trained immunity induces long-term functional upregulation of innate immune cells through epigenetic and metabolic reprogramming. An overview of the epidemiological evidence of non-specific effects of vaccines and the latest insights regarding the biological mechanisms behind this phenomenon is presented, and future research priorities and potential implications are discussed.

Neonatal BCG vaccination and atopic dermatitis before 13 months of age: A randomized clinical trial

BACKGROUND

Studies have suggested that Bacillus Calmette-Guérin (BCG) vaccination may reduce the risk of allergic diseases, including atopic dermatitis.

METHODS

The Danish Calmette Study was conducted 2012-2015. Within 7 days of birth new-borns were randomised 1:1 to BCG or no BCG. Exclusion criteria were gestational age <32 weeks, birth weight <1000 g, known immunodeficiency or no Danish-speaking parent. Data were collected through telephone interviews and clinical examinations until 13 months.

RESULTS

Clinical atopic dermatitis was diagnosed in 466/2,052 (22.7%) children in the BCG group and 495/1,952 (25.4%) children in the control group (RR = 0.90 [95% confidence intervals 0.80-1.00]). The effect of neonatal BCG vaccination differed significantly between children with atopic predisposition (RR 0.84 (0.74-0.95)) and children without atopic predisposition (RR 1.09 [0.88-1.37]) (test of no interaction, P = .04).

CONCLUSION

Among children with atopic predisposition, the number-needed-to-treat with BCG to prevent one case of atopic dermatitis was 21 (12-76).