COVID-19(15) Coronavirus disease 2019(10) airway(9) histological(6) endoscopy(6) Mast cells(6) Clinical severity(6) Corticosteroid(6) Corticosteroids(6) hypersensitivity reactions(6) pulmonary(6) cell activation(6) detect(6) severe COVID-19.(6) correlated(6) Severity Score(6) AhR(6) anaphylaxis(6) pulse methylprednisolone therapy(6) coronavirus disease(6) hypersensitivity(6) severe COVID-19(6) S1 protein(6) positive(6) nucleocapsid protein(6) analysed(6) IgE(6) PaO(6) Early convalescence(6) Anti-SARS-CoV-2 specific IgE antibodies(6)