Abstract: Background: The European Academy of Allergy and Clinical Immunology’s (EAACI) is updating the Guidelines on Food Allergy Diagnosis. We aimed to undertake a systematic review of the literature with meta-analyses to assess the accuracy of diagnostic tests for IgE-mediated food allergy. Methods: We searched three databases (Cochrane CENTRAL (Trials), MEDLINE (OVID) and Embase (OVID)) for diagnostic test accuracy studies published between 1 st October 2012 and 30 th June 2021 according to a previously published protocol (CRD42021259186). We independently screened abstracts, extracted data from full-texts, and assessed risk of bias with QUADRAS 2 tool in duplicate. Meta analyses were undertaken for food-test combination where 3 or more studies were available. Results: 149 studies comprising 24,489 patients met the inclusion criteria and were generally heterogeneous. 60.4% of studies were in children ≤12 years of age, 54.3% undertaken in Europe, ≥95% conducted in a specialized pediatric or allergy clinical setting and all included oral food challenge in at least a percentage of enrolled patients, in 21.5% DBPCFC. Skin prick test (SPT) with fresh cow’s milk and raw egg had high sensitivity (90% and 94%) for milk and cooked egg allergies. Specific IgE to individual components had high specificity: Ara h 2 had 92%, Cor a 14 95%, Ana o 3 94%, casein 93%, ovomucoid 92/91% for the diagnosis of peanut, hazelnut, cashew, cow’s milk and raw/cooked egg allergies, respectively. BAT was highly specific for the diagnosis of peanut (90%) and sesame (93%) allergies. Conclusions: SPT and specific IgE to extracts had high sensitivity whereas specific IgE to components and BAT had high specificity to support the diagnosis of individual food allergies. PROSPERO registration: CRD42021259186 Funding: European Academy of Allergy (EAACI).

Title: Notch4, uncovering an immunomodulator in allergic asthmaAuthors: Beatriz Moyaa, Manali Mukherjeeb and Parameswaran Nairba. Department of Allergy, Hospital Universitario 12 de Octubre, Madrid, Spainb. Division of Respirology, Department of Medicine, McMaster University, Hamilton & Firestone Institute for Respiratory Health, St Joseph’s Healthcare, Hamilton, ON, CanadaCorrespondence to : Beatriz Moya. Allergy Department. Hospital Universitario 12 de Octubre, Madrid, SpainEmail:[email protected] : Dr. Mukherjee is supported by investigator award from Canadian Institutes of Health Research and Canadian Allergy, Asthma, and Immunology Foundation. She has received honorarium from AZ, GSK and her university has received grants from Methapharm Speciality Pharmaceuticals. Dr. Nair is supported by the Frederick E. Hargreave Teva Innovation Chair in Airway Diseases. He has received honoraria from AZ, Sanofi, Teva, Merck, Novartis and Equillium and his university has received research grants from AZ, Teva, Sanofi, Novartis, BI and Methapharm. The authors recognize Dr. Anna Globinska for graphical abstract design and Dr. Rodrigo Jiménez-Saiz for critical review of the manuscript.Keywords: Allergic asthma; Airway inflammation; Th2 cell; Th17 cell; Treg cell; Notch4 receptorAbbreviations: Th, T helper; UFPs, pollutant ultrafine particles; AMs, alveolar macrophages; Treg cells, regulatory T cells; ILC2s, type 2 innate lymphoid cells; GDF15, cytokine growth and differentiation factor 15; IL, interleukin; IL-6R, interleukin-6 receptor; IL-4R, interleukin-4 receptorWord count: 918/1000

Groundbreaking Discoveries in ImmunologyTitle : IgE sialylation: unravelling a key anaphylactic mediatorAuthors : Beatriz Moyaa, Chiara Tontinib and Alexandra Santosc, d, e, fa. Allergy Service. Hospital Universitario 12 de Octubre, Madrid, Spainb. Lydia Becker Institute for Immunology and Inflammation, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UKc. Department of Women and Children’s Health (Paediatric Allergy), School of Life Course Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, UKd. Peter Gorer Department of Immunobiology, School of Immunology and Microbial Sciences, King’s College London, London, UKe. Children’s Allergy Service, Guy’s and St Thomas’ Hospital, London, UKf. Asthma UK Centre of Allergic Mechanisms of Asthma, London, UKCorrespondence to : Beatriz Moya. Allergy Service. Hospital Universitario 12 de Octubre, Madrid, SpainEmail: [email protected]: Ig, Immunoglobulin; Fab, antigen-binding fragments; Fc, fragment crystallizable region; FcεRI, Fc epsilon receptor I; MC, mast cells.Word count: 637/1000

In December 2019, China reported the first cases of the coronavirus disease 2019 (COVID-19). This disease, caused by the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), has developed into a pandemic. To date it has resulted in ~5.6 million confirmed cases and caused 353,334 related deaths worldwide. Unequivocally, the COVID-19 pandemic is the gravest health and socio-economic crisis of our time. In this context, numerous questions have emerged in demand of basic scientific information and evidence-based medical advice on SARS-CoV-2 and COVID-19. Although the majority of the patients show a very mild, self-limiting viral respiratory disease, many clinical manifestations in severe patients are unique to COVID-19, such as severe lymphopenia and eosinopenia, extensive pneumonia, a “cytokine storm” leading to acute respiratory distress syndrome, endothelitis, thrombo-embolic complications and multiorgan failure. The epidemiologic features of COVID-19 are distinctive and have changed throughout the pandemic. Vaccine and drug development studies and clinical trials are rapidly growing at an unprecedented speed. However, basic and clinical research on COVID-19-related topics should be based on more coordinated high-quality studies. This paper answers pressing questions, formulated by young clinicians and scientists, on SARS-CoV-2, COVID-19 and allergy, focusing on the following topics: virology, immunology, diagnosis, management of patients with allergic disease and asthma, treatment, clinical trials, drug discovery, vaccine development and epidemiology. Over 140 questions were answered by experts in the field providing a comprehensive and practical overview of COVID-19 and allergic disease.