Background: Worldwide data on epidemiology of anaphylaxis are limited, mostly due to the difficult recording of all cases. The aims of the study are to determine anaphylaxis frequence to a general E.D. before and during COVID-19 pandemic, its association with demographic and clinical characteristics. Methods: This is a retrospective study analysing clinical records from a general E.D. of Milan in two periods before (2018-2019) and during the COVID-19 pandemic (2020-2021). The analysis regarded demographic data, comorbidities, chronic therapies, causes, severity and adrenaline use. Globally data were assessed to find predictive risk factors for a severe reaction. Results: The frequence of anaphylaxis remained stable, (120/104129 = 0.12% in 2018-2019 and 72/66720 = 0.1% in 2020-2021). No differences in the occurrence of anaphylaxis were found in sex and in the 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-year periods. Gender, cardiovascular diseases, food allergy, drug allergy and Hymenoptera venom allergy did not influence the severity. A positive correlation was found with an increase in the mean age, especially in patients aged 50 or more (p<0.001). Angiotensin II receptors blockers, β-blockers, diuretics and proton pump inhibitors were associated with increasing severity (p<0.01). Conclusion: The anaphylaxis frequency in E.D. was not affected by the COVID-19 pandemic. Food anaphylaxis remained the most important cause of admission to the E.D. in our urban area. More studies are necessary to estimate the real incidence of all anaphylactic reactions.

Introduction |Shellfish allergy is an important cause of food allergies worldwide. Both in vivo and in vitro diagnostics failure nowadays is caused by the poor quality of the extracts associated with the scarce availability of allergenic molecules in the market. It is known that not all patients with shellfish allergies experience adverse reactions to mollusks. It is still unclear how to detect and diagnose correctly these patients. Aim |To investigate the features of shrimp-allergic patients either reactive or tolerant to mollusks, with the currently available diagnostic methods. Methods| Nineteen centers, scattered throughout Italy, participated in the study, enrolling patients allergic to shrimp with or without associated reactions to mollusks. Patients underwent skin tests using commercial extracts or fresh raw and cooked foods, and IgE reactivity to currently available allergenic extracts and molecules was measured in vitro. Results| Two hundred and forty-seven individuals with a history of adverse reaction to crustaceans participated in the study. Only 47.8% of them reacted after cephalopod or bivalve ingestion. None of the tests used, either in vivo or in vitro, was able to detect all selected patients. Accordingly, a great heterogeneity of results was observed with an agreement between in vivo and in vitro tests ranging between 52% and 62% of cases. Skin tests were able to identify the cephalopod and bivalve reactors (p <0.001), also using fresh cooked or raw food (p <0.001). The reactivity profile of mollusk reactors was dominated by Pen m 1, over Pen m 2 and Pen m 4 compared to the tolerant subjects, but 33% of patients allergic to shellfish were not detected by any of the available molecules. A higher frequency of shrimp hypersensitivity was recorded in northern Italy, while mollusk reactivity was more frequent in the center-south. Conclusion |The current diagnostic methods are inadequate to predict the cross-reactivity between crustaceans and mollusks. The detection of mollusks hypersensitivity must still rely on skin tests with fresh material. There is no need to exclude mollusks from shrimp allergic patients’ diet unless clinical history, the available diagnostic instruments, and/or tolerance tests support such a decision. Primary sensitization to mollusks seems possible.

We describe the case of a patient with a diagnosis of rheumatoid arthritis experiencing a mucocutaneous delayed reaction to golimumab. Anyway, there is no consensus regarding the best management of delayed reactions to biologics. Excluding allergic cross-reactivity or sensitization, we finally tested adalimumab by a graded challenge.

After a suspected allergic reactions to first dose of mRNA COVID-19 vaccine, given the PEG skin tests negativity and tolerance in vivo to PEG containing drugs, five patients were vaccinated with the second dose of Pfizer-Biontech undergoing a fractional protocol, with antihistamine premedication, without presenting immediate or delayed reactions.

The role of Immunotherapy in Chronic Urticaria is unclear, except for isolated circumstances. Hymenoptera sting causes acute urticaria and no report of CU after Hymenoptera sting can be found in the literature. We describe a case of onset of CU after multiple wasp stings that remitted during venom immunotherapy.