Anaphylaxis trend before and during pandemic: COVID-19 did not affect anaphylaxis frequency

<b>Background</b>. Data on epidemiology of anaphylaxis are difficult to record. During the lockdown in 2020-2021 due to Coronavirus disease 2019 (COVID-19), referrals to Emergency Department (E.D.) reduced. The aims of the study are to determine anaphylaxis frequency before and during COVID-19 pandemic and risk factors for severity. <b>Methods</b>. Clinical records from a general E.D. of Milan in Italy were retrospectively evaluated before (2018-2019) and during the COVID-19 pandemic (2020-2021) analyzing demographic data, comorbidities, chronic therapies, causes, severity and adrenaline use. <b>Results</b>. The frequency of anaphylaxis remained stable (120/104129 = 0.12% in 2018-2019; 72/66720 = 0.11% in 2020-2021). No differences in the occurrence of anaphylaxis were found in sex and mean age. The main causes of anaphylaxis were food (2018-2019: 53% vs 2020-2021: 51%) and drugs (2018-2019: 27% vs 2020-2021: 33%). Hymenoptera stings had a low occurrence and unidentified trigger was about 15% in each period. The severity of anaphylaxis had a similar distribution in the two periods. Gender and cardiovascular diseases did not influence the severity, instead a positive correlation was found in age over 50 yo (p<0.001). Angiotensin II receptors blockers, β-blockers, diuretics and proton pump inhibitors were associated with increasing severity (p<0.01). Adrenaline administration was similar in the two periods. <b>Conclusions</b>. Anaphylaxis frequency was not affected by the COVID-19 pandemic. Food anaphylaxis remained the most important cause in the urban area. The severity of anaphylaxis was affected by ageing and some chronic therapies, which indirectly point out the role of chronic diseases in the clinical presentation.