Reply to Wei-Zhen Tang, MD; Wei-Ze Xu, MD; and Tai-Hang Liu, PhD.Vincent Ojwang’ 1,2, Bright I. Nwaru2,3,4, Hanna-Mari Takkinen 2,5,6, Suvi M. Virtanen 2, 5, 6, 7Department of Community Health and Behavioral Sciences, School of Medicine, Masinde Muliro University of Science and Technology, Kakamega, KenyaFaculty of Social Sciences, Health Sciences Unit, Tampere University, Tampere, FinlandKrefting Research Centre, Institute of Medicine, University of Gothenburg, Gothenburg, SwedenWallenberg Centre for Molecular and Translational Medicine, University of Gothenburg, Gothenburg, SwedenDepartment of Public Health and Welfare, Finnish Institute for Health and Welfare, Helsinki, FinlandTampere University Hospital, Wellbeing Services County of Pirkanmaa, Tampere, FinlandCenter for Child Health Research, Tampere University and Tampere University Hospital, Tampere, Finland

Editorial comment on “Current options in the management of tree nut allergy: A

Allergic diseases such as asthma, atopic dermatitis and food allergies are a burgeoning health challenge in the Asia-Pacific region. Compounding this, the region has become increasingly susceptible to the impacts of climate change. The region has weathered extreme precipitation, intense heat waves, and dust storms over the recent decades. While the effects of environmental and genetic factors on allergic diseases are well understood, prevailing gaps in understanding the complex interactions between climate change and these factors remain. We aim to provide insights into the various pathways by which climate change influences allergic diseases in the Asia-Pacific population. We outline practical steps that allergists can take to reduce the carbon footprint of their practice on both a systemic and patient-specific level. We recommend that allergists optimise disease control to reduce the resources required for each patient's care, which contributes to reducing greenhouse gas emissions. We encourage the responsible prescription of metered dose inhalers by promoting the switch to dry powder inhalers for certain patients, at each clinician's discretion. We also recommend the utilisation of virtual consultations to reduce patient travel while ensuring that evidence-based guidelines for rational allergy management are closely adhered to. Finally, eliminating unnecessary testing and medications will also reduce greenhouse gas emissions in many areas of medical care.

Background: Association of early pregnancy body mass index (BMI) and maternal gestational weight gain (GWG), and asthma and allergic disease in children is unclear. Methods: We analyzed data from 3,176 mother-child pairs in a prospective birth cohort study. Maternal anthropometric measurements in the first and last antenatal clinic visits were obtained through post-delivery questionnaires to calculate early pregnancy BMI and maternal GWG. Asthma and allergic diseases in children by the age of 5 years was assessed using a validated questionnaire. Furthermore, serum samples were analyzed for IgE antibodies to eight allergens. We applied Cox proportional hazards and logistic regression analyses to estimate the association of early pregnancy BMI and maternal GWG (as continuous variables and categorized into quarters), and asthma, atopic eczema, atopic sensitization, and allergic rhinitis in children. Results: Early pregnancy BMI and maternal GWG were not associated with asthma and allergic disease in children when analyzed as continuous variables. Compared to the first quarter (GWG <0.32 kg/week), mothers in the third quarter (GWG 0.42-0.52 kg/week) had children with higher odds of developing atopic eczema (adjusted OR 1.49, 95% CI [1.13-1.96]) by age 5 years. Conclusion: The association of early pregnancy BMI and maternal GWG and asthma and allergic disease in children is inconsistent. High maternal GWG may be associated with increased odds of atopic eczema.

Hereditary angioedema (HAE) is a rare, life-threatening genetic disorder characterized by acute, recurrent and unpredictable episodes of cutaneous or submucosal angioedema, mediated by bradykinin, due to C1 inhibitor (C1INH) abnormalities in the vast majority of cases. The epidemiology of the disease is poorly documented in children. Clinical manifestations usually appear during childhood or early adolescence. Classical signs, preceded by prodromal symptoms in 50 % of cases, include transient, localized, non-pitting, non-pruritic swelling of deep dermal/subcutaneous or mucosal/submucosal tissues, leading to oedema of the extremities, face, lips, tongue, trunk and genitals, recurring gastrointestinal symptoms and laryngeal edema possibly causing asphyxiation and death. Diagnosis is often delayed due to low awareness in the medical community, and particularly challenging in case of isolated abdominal crises or atypical presentation and in neonates or infants. It relies on biological tests (measurement of serum/plasma levels of C1INH function, C1INH protein, and C4), genetic testing in selected cases, and imaging for differential diagnosis of acute abdominal crises. Main differential diagnosis for peripheral oedema is mast cell-mediated oedema that accounts for 95 % of angioedema in clinical practice. Quality of life can be significantly impaired. Disease management includes treatment of attacks, short-term and long-term prophylaxis, psychological support, avoidance of triggers, patients’ and parents’ education and coordination of all stakeholders, ideally within a specialized healthcare network. New plasma kallikrein inhibitors, namely lanadelumab (subcutaneous route) and berotralstat (oral route) have facilitated long-term prophylaxis thanks to improved usability.

A document by Hugo Gagnon. Click on the document to view its contents.

Background Consumption of raw cow’s milk has repeatedly been shown to protect from asthma, allergies, and respiratory infections. As raw milk bears potential health hazards, it cannot be recommended for prevention. Therefore, we performed an intervention study with microbially safe but otherwise minimally processed cow’s milk. Here we describe feasibility and safety of the trial. Methods The MARTHA trial (DRKS00014781) was set up as a double-blind randomized intervention in a population residing in Bavaria. Infants from 6 to 36 months of age consumed minimally processed cow’s milk (intervention arm) or ultra-heat-treated (UHT) semi-skimmed milk (comparator arm). Results At the age of 6 to 12 months, 260 infants were enrolled, with 72% having a family history of atopy. The extensive screening system for milk consumption and symptoms suggestive of adverse events was well accepted with 22,988 completed weekly surveys and an average completion of 82% surveys sent out. The children consumed the study milk on average on 457 days (61% of intervention days). The intervention proved to be safe without any case of milk allergy or milk intolerance under the intervention in both arms. All 6 cases of serious adverse events were unrelated to milk. The most common reason was unscheduled hospitalization of more than 3 days. Conclusions The intervention with minimally processed milk and the study instruments proved feasible. During the age of 6 to 36 months, there was no increased risk of milk allergy in a population with a substantial proportion of family history of atopy.

The recognition of constipation as a possible non-Immunoglobulin E (IgE) mediated allergic condition is challenging because functional constipation (unrelated to food allergies) is a common health problem with a reported worldwide prevalence rate of up to 32.2% in children. However, many studies in children report challenge proven cow’s milk allergy and constipation as a primary symptom, have found that between 28-78% of children improve on a cow’s milk elimination diet. Due to the paucity of data and a focus on IgE mediated allergy, not all food allergy guidelines list constipation as a symptom of food allergy. Yet, it is included in all cow’s milk allergy guidelines available in English language. The Exploring Non- IgE Mediated Allergy(ENIGMA) Task Force (TF) of the European Academy for Allergy and Clinical Immunology (EAACI) considers in this paper constipation in the context of failure of standard treatment and discuss the role of food allergens as culprit in constipation in children. This position paper has used the Delphi approach in reaching consensus on both diagnosis and management, as currently published data is insufficient to support a systematic review.

Background: Basophil activation test (BAT) or the mast cell activation test (MAT) are two in vitro tests that are currently being studied in food allergy as diagnostic tools as an alternative to oral food challenges (OFCs). We conducted a meta-analysis on BAT and MAT assessing their specificity and sensitivity in diagnosing peanut allergy. Methods: Six databases were searched for studies on patients suspected of having peanut allergy. Studies using BAT or MAT to peanut extract and/or component as diagnostic tools with results given in percentage of CD63 activation were included in this meta-analysis. Study quality was evaluated with the QUADAS-2 tool. Results: On the eleven studies identified, eight focused exclusively on children, while three included a mixed population of adults and children. Only one study provided data on MAT, precluding us from conducting a statistical analysis. The diagnostic accuracy of BAT was higher when stimulated with peanut extract rather than Ara h2 with a pooled specificity of 96% (95% CI: 0.89-0.98) and sensitivity of 0.86 (95% CI: 0.74-0.93). The sensitivity and specificity of BATs in discriminating between allergic and sensitized patients was studied as well with pooled analysis revealing a sensitivity of 0.86 (95% CI: 0.74; 0.93) and a specificity of 0.97 (95% CI: 0.94, 0.98). Conclusion: BATs, when stimulated with peanut extracts, exhibit a satisfactory sensitivity and specificity for the diagnosis of peanut allergy and can help to discriminate between allergic individuals and those only sensitized to peanut. More investigations on the potential for MATs diagnostic methods are warranted.

Background: Immunomodulatory proteins in human milk (HM) can shape infant immune development. However, strategies to modulate their levels are currently unknown. This study investigated whether maternal prebiotic supplementation alters the levels of immunomodulatory proteins in HM. Methods: The study was nested within the SYMBA double-blind randomised controlled trial (ACTRN12615001075572), which is investigating the effects of maternal prebiotic (scGOS/lcFOS) supplementation from <21 weeks gestation during pregnancy until 6-months postnatal during lactation on child allergic disease risk. Mother-child dyads receiving prebiotics (n=46) or placebo (n=54) were included in this study. We measured the levels of 24 immunomodulatory proteins in HM collected at 2, 4 and 6 months. Results: Cluster analysis showed that the overall immunomodulatory protein composition of milk samples from both groups was similar. Prebiotic-supplemented women had decreased levels of TGF-β1 at 2 months, IgG1 at 4 months and sCD14 at 6 months (p=0.03, 0.03 and 0.04, respectively). IL-5 levels were increased in the prebiotic group compared to the control group at 4 and 6 months (p=0.02 and 0.04, respectively). After adjustment for multiple comparisons, the statistical differences between the prebiotic and placebo groups were no longer present (p>0.05). Conclusion: This study is the first to comprehensively trial scGOS/lcFOS intake during pregnancy and indicate potentially altered levels of immunomodulatory proteins in HM. Future research will elucidate the significance of change in milk content in immunomodulatory compounds in the prevention of allergy risk (and beyond), filling a major gap in dietary advice to pregnant and/or lactating women.

A large and growing corpus of epidemiologic studies suggests that the population-level burden of pediatric FA is not equitably distributed across major sociodemographic groups, including race, ethnicity, household income, parental educational attainment, sex). As is the case for more extensively studied allergic disease states such as asthma and atopic dermatitis) epidemiologic data suggest that FA may be more prevalent among certain populations experiencing lower socioeconomic status (SES), particularly those with specific racial and ethnic minority backgrounds living in highly urbanized regions. Emerging data also indicate that these patients may also experience more severe FA-related physical health, psychosocial and economic outcomes relating to chronic disease management. However, many studies that have identified sociodemographic inequities in FA burden are limited by cross-sectional designs that are subject to numerous biases, which can reduce the epidemiologic utility of the resulting estimates. Compared to cross-sectional study designs or cohorts that are recruited during childhood, birth cohorts can offer advantages relative to other study designs when investigators seek to understand causal relationships between exposures occurring during the prenatal or postnatal period and the atopic disease status of individuals later in life. Numerous birth cohorts have been established across recent decades, which include evaluation of food allergy-related outcomes, and a subset of these also have measured sociodemographic variables that, together, have the potential to shed light on the existence and possible etiology of sociodemographic inequities in food allergy. This manuscript attempts to survey the current state of this birth cohort literature and draw insights regarding what is currently known, and what further information can potentially be gleaned from thoughtful examination and further follow-up of ongoing birth cohorts across the globe.

Editorial comment on the Special Issue “Omics in Food Allergy”Riccardo Castagnoli1,2, Ivan Taietti1,2,*, Agnes Sze-Yin Leung3, Philippe Eigenmann41. Pediatric Unit, Department of Clinical, Surgical, Diagnostic, and Pediatric Sciences, University of Pavia, Pavia, Italy2. Pediatric Clinic, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy3. Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, China4. Pediatric Allergy Unit, Department of Pediatrics, Gynecology and Obstetrics, University Hospitals of Geneva, Geneva, SwitzerlandORCID:Riccardo Castagnoli: 0000-0003-0029-9383Ivan Taietti: 0000-0002-0372-523XAgnes Sze-Yin Leung: 0000-0001-8249-4478Philippe Eigenmann: 0000-0003-1738-1826Corresponding author:Ivan Taietti, MD;Pediatric Unit, Department of Clinical, Surgical, Diagnostic, and Pediatric Sciences, University of Pavia, 27100 Pavia, [email protected]; +39 340 7092400.Food allergy (FA), defined as an adverse reaction to food mediated by the immune system, is a significant public health issue with increasing prevalence over the past decades. Although FA affects up to 10% of children, the precise mechanisms underlying FA development and persistence remain inadequately understood1. Food immunotherapy has been successful in increasing the threshold of tolerance in individuals with persistent FA (desensitization), and in a subset, sustained unresponsiveness (remission) can be achieved. A combination of environmental and genetic factors is considered to be involved in the tolerance induction to food allergens. However, to date, it has been difficult to fully dissect the complexity of the biological determinants involved in FA.The emergence of “omics” sciences, including genomics, transcriptomics, proteomics, and metabolomics, is revolutionizing the basic and translational research approach, allowing for the comprehensive study of biological processes through analyzing and integrating multiple datasets from various biological perspectives.Moreover, epigenetic studies that evaluate the role of gene expression modifiers are deepening our understanding of the interaction between genetic predisposition and environmental influences.The Special Issue “Omics in Food Allergy” aims to present current knowledge and future perspectives in the field of FA through the lenses of omics sciences.Chun et al. and Lehmann et al. provide a detailed overview of epigenetic mechanisms involved in FA, including DNA methylation and microRNA (miRNAs)2,3. DNA methylation refers to the covalent addition of a methyl group, typically to a cytosine in a CpG dinucleotide in DNA. This limits access for transcription, frequently in the promoter region, leading to reduced gene expression. Moreover, miRNAs are small RNAs transcribed from intergenic or intronic genomic loci that decrease gene expression by mRNA degradation and translational inhibition. Of note, Chun et al. described two different approaches in investigating FA mechanisms: (i) the epigenome-wide research approach and (ii) candidate-gene investigations. The epigenome-wide research approach identified genomic regions differently methylated and regulated, involved in FA causation, antigen presentation, T cell development, and reaction severity. Candidate-gene investigations focused on Th1, Th2, T regulatory, and innate genes of interest in FA, highlighting the importance of methylation changes in specific candidate genes. In this context, for cow’s milk allergy (CMA), the attention is focused on novel genetic loci involved in Th1/Th2 differentiation pathways and potential B-cell dysfunction4. Of note, miRNA seems to be involved in CMA as demonstrated by the downregulation of mi193a-5p, a post-transcriptional regulator of IL-4 expression, in infants with CMA5. Moreover, methylation levels in peripheral blood mononuclear cells for IL-4, IL-5, IL-10, and IFN-γ negatively correlate with their respective serum cytokine concentrations and vary according to CMA status (active, resolved, or non-CMA). Finally, Chun et al. reviewed ongoing research aimed at finding DNA methylation predictors of food challenges. Initial work based on the concept of epigenetic markers as biomarkers of disease and treatment demonstrated promise for applying DNA methylation markers to potentially improve how we assess and manage patients with FA, but further validation in larger cohorts and work to practically translate such biomarkers to clinical practice is advocated2.Metabolomics may reflect the integration of genetic, transcriptomic, and proteomic variations with environmental factors, thus reflecting molecular processes of diseases. A metabolome approach would facilitate the identification of surrogate metabolite markers correlating with the disease activity and prognosis. Lee et al. reported an updated overview of metabolomics’s current application in the FA field. Alterations to the gut microbiota induced by Western dietary patterns are likely to profoundly affect host immunity and play a significant role in FA. Metabolites of interest include short-chain fatty acids (SCFAs), bile acid metabolites, and tryptophan metabolites due to their essential roles in normal immune development and homeostasis. SCFAs appear to be reduced in FA patients. Of note, it has been shown that bacterial SCFAs could protect against FA as a consequence of a high-fiber diet in mice. Accordingly, a reduction in Bifidobacterium during infancy, with a consequent reduction in SCFA levels is associated with an increased risk of allergy6. In peanut allergy, oral dysbiosis, reduced oral SCFA levels, and increased oral mucosal Th2 cytokine secretion characterize patients affected, and low fecal SCFAs at a young age could raise the risk of developing FA. Bile acid levels in stool seem to be involved in FA development and persistence, but blood level measurements are advocated to better characterize their role. Moreover, sphingolipids may modulate the function of invariant natural killer T cells and contribute to maintaining intestinal balance and protecting against FA through the modulation of the mast cells’ responsiveness. Sphingolipid dysmetabolism is involved in FA development as a consequence of immune dysregulation in modulating the differentiation of regulatory T cells and Th17 cells that is relevant in FA. Interestingly, some fecal sphingolipids seem to confer protection against FA while reduction of other of them seems to be associated with increased risk of FA, likewise the reduction in serum sphingolipids. Unfortunately, no definitive evidence is available to distinguish whether the sphingolipids modulating this FA effect are dietary or microbial-derived. Metabolites of tryptophan from kynurenine and indole pathways are linked to the function of the intestinal barrier and mucosal immune responses (mainly T regulatory cells) and contribute to intestinal homeostasis. A reduction in these pathways is linked to multiple FA in children. To date, the role of omega-3-polyunsaturated fatty acids metabolites is not clearly defined in FA. However, 17-hydroxy-docosahexaenoic acid (17-HDHA) has been reported to inhibit IgE production by B cells and to suppress the differentiation of naïve B cells into IgE-secreting cells7.The gut microbiome (GM) and its metabolic product, as previously mentioned, play an important role in FA development. TheBifidobacteriaceae family and bacteria of theLactobacillales order are consistently reported lower in CMA children. At the same time, the Firmicutes phylum, primarily associated with the Clostridia class, is consistently increased in mice and human studies. It seems discordant with the observation that infants with resolved CMA were reported to have enrichedClostridia class at 3-6 months but with non-conclusive data. However, Savova et al. showed that GM with enriched Clostridiaclass, reduced Lactobacillales order, and reducedBifidobacterium genus is associated with CMA in early life. Emerging evidence shows that prebiotics, probiotics, and symbiotics, may be a promising adjuvant in promoting tolerance acquisition. ElevatedBifidobacterium genus and reduced Clostridia class members were consistently observed post-treatment with Bifidobacteriumstrains probiotics or after lactose-supplemented extensively hydrolyzed formula (EHF) treatment strategy but with decreased levels ofLactobacillus genus in those treated with Bifidobacteriumstrains probiotics. Gaps remain in understanding the relationship between microbiome and immune response and between transcriptomics (including genes related to the immune response) and GM. In vivo ,Bifidobacterium bifidum has been shown to reduce allergy symptoms, lower serum IgE and raise IgG2 levels, decrease the pro-inflammatory cytokines (TNFα, IL- 1β, and IL-6), and increase the anti-inflammatory cytokine IL-10 in CMA-patients8. Recently, fiber diet has been shown to modulate the disease course of FA through diet-driven changes in the GM9. It is necessary to conduct further research on the impact of GM on FA development and persistence.Lastly, oral immunotherapy (OIT) may provide an active treatment that enables to increase the amount of food that the patient can intake without reaction during treatment (i.e., desensitization), and reduces the risk of potential life-threatening allergic reaction in the event of accidental ingestion10 Unfortunately, there are still significant gaps in understanding the immune mechanisms following OIT, but increasing knowledge about transcriptional pathways associated with its outcomes is available to date11. Ashley et al.12 show that OIT-induced remission of FA is linked to the anergic T cell state mediated by anergy of memory T cells associated with mantained T regulatory cell activity. Suppression of the Th2 transcriptional signals in Th2A-like cells was linked to desensitization following OIT. Moreover, the dampened Th2 and Th1 signatures in effector cells are linked with FA remission, while baseline inflammatory signals in Th1 and Th17 effector cells were associated with poorer outcomes following OIT. Type I interferons were recently identified as potential regulators of remission following OIT because of their key role in the suppression of the Th2 antigen response through regulatory action on GATA3 and the high-affinity IgE receptor. Moreover, an early transient increase in TGF-β producing cells one year into treatment seems to be associated with good clinical outcomes. In addition, persistent activation of FOXP3, expressed by T regulatory cells, may be a critical requirement for lasting persistence of remission12.Comprehensive multi-omics studies are essential to understand FA mechanistically, as highlighted by this Special Issue. “Omics” studies of FA are of great interest as they allow for a thorough understanding of the complexity of FA development and therapeutic outcomes. This has a fundamental impact on approaches to precision medicine.

Letter to the Editor

Background: Viral wheeze is an important risk factor for asthma, which comprises several respiratory phenotypes. We sought to understand if the etiology of early life wheezing illnesses relates to childhood respiratory and asthma phenotypes. Methods: Data were collected prospectively on 429 children in the Urban Environment and Childhood Asthma (URECA) birth cohort study through age 10 years. We identified wheezing illnesses and the corresponding viral etiology (PCR testing of nasal mucus) during the first three years of life. Six phenotypes of respiratory health were identified at 10 years of age based on trajectories of wheezing, allergic sensitization, and lung function. We compared etiology of early wheezing illnesses on these respiratory phenotypes and the development of asthma. Results: In the first three years of life, at least one virus was detected in 324 (67%) of the 483 wheezing episodes documented in the study cohort. Using hierarchical partitioning we found that non-viral wheezing episodes accounted for the greatest variance on asthma diagnosed at both 7 and 10 years of age (8.0% and 5.8% respectively). Rhinovirus wheezing illnesses explained the most variance on respiratory phenotype outcome followed by non-viral wheezing episodes (4.9% and 3.9% respectively) at 10 years of age. Conclusion and Relevance: Within this high-risk urban-residing cohort early life, non-viral wheezing episodes were frequently identified and associated with asthma development. Though rhinovirus wheezing illnesses had the greatest association with phenotype outcome, the specific etiology of wheezing episode in early life provided limited information about subsequent wheezing phenotypes.

Food allergy is postulated to originate from cutaneous sensitization through a disrupted skin barrier, particularly in atopic dermatitis (AD). Strategies for food allergy prevention currently centre around early allergic food introduction, but there is now increasing evidence for the role of early skin barrier restoration in the form of prophylactic emollient therapy and early aggressive, proactive treatment of established AD for food allergy prevention. Research gaps that remain to be addressed include the type of emollient or anti-inflammatory medication which confers the greatest efficacy in preventive or proactive skin treatment respectively, the duration of therapy, and the window of opportunity for these interventions.

To the Editor,

Editorial Comment on “Atopic outcomes at 2 years in the CORAL cohort, born in COVID-19 lockdown”Sandoval-Ruballos, Mónica1, Carmen Riggioni2,3, Jon Genuneit41 Pediatric Allergy and Immunology Clinic, Guatemala, Guatemala.2Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.3Khoo Teck Puat-National University Children’s Medical Institute, National University Hospital, National University Health System, Singapore.4 Pediatric Epidemiology, Department of Pediatrics, Medical Faculty, Leipzig University, Leipzig, GermanyAtopic conditions have been on the rise globally, particularly in industrialized nations.(1) This phenomenon has spurred interest in the potential connection between the surge in allergic disorders and modern lifestyles characterized by reduced microbial exposure and increased hygiene practices. While the hygiene theory proposes that the early childhood microbial environment plays a pivotal role in shaping immune system development, reducing the risk of atopic conditions, more recent findings have emphasized the role of a defective epithelial barrier. This recent perspective suggests that the upsurge in agents damaging the epithelial barrier, associated with industrialization and modern living, is at the core of the escalation of allergic, autoimmune, and other chronic conditions. Notably, these effects may have intensified during the pandemic. (2) (3)The SARS-CoV-2 pandemic in early 2020 prompted various lockdowns and stringent hygiene measures, offering an intriguing opportunity to investigate the impact of these altered environmental factors on the prevalence of atopic conditions. The CORAL study is a longitudinal observational project, following 365 infants born in Ireland, during the initial pandemic period (March-May 2020) from enrollment to 24 months of age. (4) The authors compared the occurrence of allergic diseases with a pre-pandemic Irish cohort (BASELINE study 2008-2011). (5) This investigation aims to shed light on the pandemic’s potential impact on infant allergic disease development.At first glance, the CORAL cohort exhibited higher rates of atopic dermatitis (AD) at both 12 and 24 months compared to BASELINE. However, this finding may reflect a gradual increase in AD incidence within their population, given that the BASELINE cohort was born about one decade earlier. Alternatively, the early-life environment during the lockdowns may have played a role. In addition, the authors delineated three patterns of AD. A more severe AD phenotype was noted among infants with persistent AD diagnosis at 24 months, and AD-persistent infants were more likely to be sensitized. This observation aligns with prior studies, highlighting the significance of severity, and atopic sensitization as relevant determinants of AD prognosis.(6)While AD rates were higher in the CORAL cohort, they exhibited lower rates of food sensitization and allergy compared to BASELINE, particularly significant in peanut sensitization and egg allergy, with a non-significant trend towards lower peanut allergy. Importantly, parents received complementary feeding advice at 6 months, emphasizing early peanut introduction. Therefore, these outcomes may be attributed to recommended early allergen introduction, along with other factors like increased breastfeeding, fewer infections during the first 12 months (7), lower antibiotic exposure, and sustained dietary allergen exposure during lockdown. The relevance of early allergen introduction, especially for peanut and egg, has gained prominence in international guidelines more recently, owing to accumulating evidence underscoring its role in directly reducing the development of food allergy (8).At 24 months, antibiotic usage and childcare outside home increased AD likelihood potentially linked to decreased infection rates and antibiotic use in children not attending daycare, preserving microbiota integrity. Intriguingly, despite more AD cases in children attending daycare, they exhibited lower allergic sensitization rates. Aeroallergen sensitization at 24 months was more pronounced among children cared for solely at home, thus reflecting environmental influence. From a theoretical perspective, it is plausible that the lockdown measures, which led to a substantial increase in indoor confinement, may have resulted in heightened exposure to indoor allergens,(9) consequently leading to higher sensitization rates. Furthermore, allergic sensitization at 12 and 24 months was associated with AD at both time points and with asthma diagnosis at 24 months.Despite its valuable insights, the CORAL study has limitations, including a small cohort size and potential selection bias, as it represented only 12% of eligible children. Here, high breastfeeding rates and low parental smoking rates may limit generalizability. Additionally, the small sample size might hinder the identification of associations that might be evident in larger cohorts.Other studies conducted during the pandemic have primarily focused on assessing the impact on allergic conditions during lockdowns. They have often reported positive effects of interventions such as hygiene, mask usage, and social distancing in reducing air pollution and lowering infection rates, potentially resulting in a reduced impact on allergic conditions (10). The CORAL study stands out among these studies due to its specific objective of evaluating the effect of lockdowns on the incidence of allergic diseases. Finally, it provides valuable insights into how the pandemic have influenced the health of infants born during this period. While the increased incidence of AD initially raises concerns, the lower rates of food sensitization and allergies suggest the positive effects of evolving allergy practices, particularly early allergen introduction. Furthermore, the beneficial impacts of lockdown, such as increased breastfeeding and reduced antibiotic use, may outweigh the anticipated risks associated with reduced early-life microbial exposures.This study enhances our understanding of the real-world impact of early-life environments on allergic disease risk. Continuous monitoring of the CORAL cohort into later childhood will reveal the lasting consequences of being born during the pandemic. These findings underscore the intricate interplay between environmental factors, infant health, and the development of allergies in a rapidly evolving landscape of healthcare practices.

Background: There has been increasing interest in elucidating the relationship between adenoid hypertrophy (AH) and allergic rhinitis (AR). However, the impact of aeroallergen sensitization patterns on children concurrently experiencing AH and AR remains unclear. Methods: Patients aged 2-8 years (January 2019 to December 2022) with nasal symptoms were assessed for allergies, adenoid size and respiratory viral infection history. The levels of serum total immunoglobulin E (IgE) and specific IgE and flexible nasal endoscopy were performed. We analyzed the relationship between AH and sensitization patterns and lymphocyte subpopulations in adenoid samples using flow cytometry. Results: 5281 children were enrolled in our cohort. 56.5% of children was diagnosed with AR and 48.6% with AH. AR was more prevalent in AH children compared to nAR. Compared to non-sensitized, those with AR polysensitized to molds had a higher prevalence of AH (adjusted OR 1.61, 95%CI 1.32-1.96) and a greater occurrence of two or more respiratory viral infections, particularly in cases with adenoidectomy. In AH-AR children, adenoid tissues showed reduced frequencies and corrected absolute counts of regulatory T cells (Tregs), activated Tregs, class-switched memory B cells (CSMB), natural killer (NK) T cells and NK subpopulations compared to AH-nAR children. Polysensitization in AH-AR children correlated with lower CSMB frequencies. Conclusion: Polysensitivity to molds significantly increased the risk of AH in children with AR. Adenoids of AR children demonstrated less number of B cells, NK cells and Treg cells with an effector/memory phenotype, which was closely linked to sensitization models and respiratory viral infection, particularly concerning CSMB.