The spectrum of COVID-19 infection includes acute respiratory distress syndrome (ARDS) and macrophage activation syndrome (MAS), although the histological basis for these disorders has not been thoroughly explored. Post-mortem pulmonary and bone marrow biopsies were performed in 33 patients. Samples were studied with a combination of morphological and immunohistochemical techniques. Bone marrow studies were also performed in three living patients. Bone marrow post-mortem studies showed striking lesions of histiocytic hyperplasia with hemophagocytosis (HHH) in most (16/17) cases. This was also observed in three alive patients, where it mimicked the changes observed in hemophagocytic histiocytosis. Pulmonary changes included a combination of diffuse alveolar damage with fibrinous microthrombi predominantly involving small vessels, in particular the alveolar capillary. These findings were associated with the analytical and clinical symptoms, which helps us understand the respiratory insufficiency and reveal the histological substrate for the macrophage activation syndrome-like exhibited by these patients. Our results confirm that COVID-19 infection triggers a systemic immune-inflammatory disease and allow specific therapies to be proposed.

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE‐mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE‐mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well‐defined, highly pure molecules for component‐resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the “EAACI Molecular Allergology User's Guide” (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state‐of‐the‐art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Presenting prevalence, characteristics and outcome of asthmatic patients with T2 diseases in hospitalized subjects with COVID-19 in Madrid, Spain SUPPLEMENT Introduction. The first confirmed case of coronavirus disease 2019 (COVID-19) in Spain was reported in Madrid at the end of February 2020. Soon after, Madrid reported an outbreak, and cases in Spain increased dramatically, as one of the countries had more cases in the world. Material and Methods. Demographic data, smoking status, non-atopic comorbidities, presence of atopy, symptoms, clinical, radiological and laboratory data on-admission and discharge, need of ICU (Intensive Care Unit) admission days of hospitalization and death were analyzed. Severity of COVID-19 on-admission was classified according to the FIO 2 required: A0 (FIO 2 21%), A1 (FIO 2 up to 35%), A2 (35% >FIO 2 ≤60%) and A3 (FIO 2 > 60%). For asthmatic patients, data related to severity [9], treatment, compliance, and control before COVID-19 were collected together with exacerbation during hospitalization. Compliance was based on refill medication data on electronic prescription during the last year, good compliance was considered as  80% of refills. Asthmatic patients were categorized as non-allergic and allergic (by positive prick test to aeroallergens).

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