No Yellow Fever Vaccine Reactions in IgE-Mediated Egg Allergic Patients.

INTRODUCTION: Egg allergy usually manifests during the initial 2 years of life, a period in which most vaccinations are administered. This often leads to delays in the application of some vaccines in patients with egg allergies, exposing them to a risk of contracting preventable infections. The aim of the study was to describe the frequency of reactions after applying the yellow fever vaccine (YFV) within a population with egg allergy. METHODS: This was a cohort study with retrospective, multicenter data (2014-2023). Patient records diagnosed with egg allergy were gathered from their initial egg-related reactions until their YFV administration. Information was also collected about hypersensitivity tests conducted for egg and YFV such as the skin prick test (SPT) and intradermal test (IDT). RESULTS: Among the 171 records analyzed, 23.9% of patients had a history of egg anaphylaxis. Out of these, 5 patients had a positive SPT and 21 IDT with the YFV. All patients tolerated the application of YFV without developing hypersensitivity reactions, regardless of the results of the YFV tests, the severity of egg reactions, the number of egg reactions, or the time since the last egg reaction. Out of the total patient cohort, 46.1% (79 individuals) encountered delays in receiving the YFV, and in this subset, 14% faced delays lasting longer than 12 months. CONCLUSION: The risk of allergic reactions with the YFV remains low. YFV tests generate delays in the vaccine application without providing high diagnostic accuracy. YFV should not be deferred even in patients with a history of severe egg reactions.

IgE, blood eosinophils and FeNO are not enough for choosing a monoclonal therapy among the approved options in patients with type 2 severe asthma.

Type-2 inflammation is the most frequent endophenotype of asthma. Different biomarkers have been proposed to identify this inflammation because highly effective therapies have improved type-2 severe asthma control. We investigated the frequency of some biomarkers of type-2 inflammation (total IgE, sIgE, blood eosinophil, and FeNO) in the framework of severe asthma and assessed its ability to help us to choose the best biological therapy for each patient. Different scenarios (sensitivity analysis) were evaluated according to the biomarkers proposed for each biological therapy in 72 patients with type-2 severe asthma. Between 54.1% and 68% of patients could receive at least 2 different biological therapies and 34.7%-40.2% could receive any of the 3 types of therapies (anti-IgE, anti-eosinophil, anti-IL4). Biomarkers help to identify type-2 severe asthma but total IgE, sIgE, blood eosinophil, and FeNO are not enough to select 1 specific therapy. With the increasing arrival of new biological therapies, it is necessary to identify new biomarkers that allow us to improve our selection criteria for the best therapy for each patient or to construct a prediction rule.