PATIENTS
We performed a retrospective study on patients who presented at the ER service of several Italian hospitals with symptoms suggestive of atypical pneumonia and were subsequently hospitalized with a diagnosis of SARS-CoV-2 infection based on the detection of viral nucleic acid in nasal and/or pharyngeal clinical specimens. Most patients were admitted in Covid-19 centers sited in Lombardy (the Italian region most heavily affected by Covid-19), while the remaining patients came from centers in other Italian regions, including Lazio and Aosta Valley. The doctors working in these centers recorded the clinical data of their inpatients with specific reference to respiratory allergy and graded the severity of their respiratory disease at the end of their hospital stay. Patients were considered “atopic” if they had an unequivocal history of respiratory allergy to seasonal and/or perennial airborne allergens confirmed by skin prick tests carried out in a specialist allergy center and/or by elevated specific IgE. Age, sex, and smoking habits were recorded along with several co-morbidities including diabetes, hypertension, coronary heart disease, and thrombosis. The respiratory consequences of the viral infection were classified as mild, severe, or very severe based on no need for respiratory assistance, need for non-invasive respiratory assistance or need for invasive respiratory assistance or death, respectively. Patients’ data were anonymized, and the internal review board of the promoting center approved the study.