IgE-mediated cow's milk allergy in Brazilian children: Outcomes of oral food challenge.

Background: Oral food challenge (OFC) is useful for diagnosing food allergies and assessing tolerance, but severe reactions may occur during the procedure. Objective: To characterize the frequency and severity of reactions during cow's milk (CM) OFCs. Methods: A cross-sectional study was conducted to analyze the outcome of cow's milk oral food challenges (CMOFCs) performed to confirm IgE-mediated CM allergy or to assess food tolerance. CM was given first as baked milk (BM), followed by whole CM if there was no prior reaction to BM. An OFC was considered positive if IgE-mediated symptoms developed up to 2 h after ingestion. Symptoms were described and variables including age at OFC, prior anaphylaxis, other atopic diseases, and skin test results were compared according to the OFC outcomes. Results: A total of 266 CMOFCs were performed, including 159 patients with a median age of 6.3 years old. One hundred thirty-six tests were positive and 62 resulted in anaphylaxis. Thirty-nine anaphylactic reactions were observed up to 30 min after the first dose. Severe anaphylaxis (cardiovascular and/or neurological involvement) was reported in 5 tests. A second dose of epinephrine was required in 3 tests, and 1 presented a biphasic response. Younger patients had a higher risk of anaphylaxis during baked milk oral food challenge (BMOFC) (p = 0.009). The frequency of anaphylaxis was higher in patients submitted to BM (p = 0.009). Conclusions: Anaphylaxis is a known complication of CMOFCs even when there is no prior anaphylaxis or when conducted with baked products. This study reinforces the importance of conducting OFC in appropriate settings with a well-trained team.

Safety of yellow fever vaccine administration in confirmed egg-allergic patients.

Yellow fever vaccine (YFV) is recommended in endemic areas but represents a risk for egg-allergic patients, as it is cultivated in embryonated eggs. This study aims to describe the outcomes of yellow fever vaccination in patients with confirmed egg allergy (EA). Methods:A prospective study was conducted from January 2018 to September 2019. EA was diagnosed through positive oral food challenge (OFC), recent history of anaphylaxis following egg contact (anaphylaxis in the last 6 months) or immediate allergic reaction in the last 2 months with positive specific IgE. A skinprick test (SPT) with YFV was performed. If the SPT was negative, an intradermal test (ID) was performed at a 1:100 dilution. If the ID was negative, a full dose of YFV was administered. If the skin prick test or ID were positive, the YFV was administered using a graded dosing protocol. Results: It was included 58 patients with confirmed egg allergy (36 M:22F), with a median age of 2.3 years (0.7-13.9 y/o). Forty-two patients had a positive OFC. Nine reported recent anaphylaxis. The other 7 had reactions in the last 2 months with positive specific IgE. During OFC, 15 presented anaphylaxis, while the other 27 presented hives and/or angioedema or vomiting. SPT with YFV was negative in all patients. ID was negative in 48 patients who uneventfully received a full dose of YFV. Ten patients had a positive ID and received YFV in graded doses. Six patients presented a mild reaction controlled with antihistamines, and 4 patients received the vaccine without reactions. Positive ID was significantly related to the vaccine reaction (p < 0.0001). Administration of YFV using a specific protocol was safe even in anaphylactic patients. However, we recommend performing the ID, which can help predict a higher risk of vaccine reaction. An appropriate setting is required to control adverse events.

Segurança da vacina de febre amarela em pacientes comprovadamente alérgicos à proteína do ovo / Safety of yellow fever vaccine in egg allergic patients

Introdução: A vacina de febre amarela, recomendada em áreas endêmicas, é contraindicada em alérgicos à proteína do ovo (APO) por ser cultivada em ovos de galinha embrionados. Objetivo: O objetivo do estudo foi mostrar a segurança da vacina de febre amarela em pacientes comprovadamente APO. Método: Foi realizado estudo prospectivo em hospital quaternário, no período de janeiro a outubro de 2018. Foram incluídos pacientes com APO confirmada por teste de provocação oral (TPO), reação anafilática à proteína do ovo nos últimos 6 meses, ou reação de APO nos últimos 2 meses associada à IgE específica positiva. Todos foram submetidos ao teste de puntura com a vacina na apresentação pura. Se negativo, realizado teste intradérmico (ID) com a vacina na diluição de 1:100. Se ID negativo, vacina aplicada em dose plena. Se teste de puntura ou ID positivo, vacina aplicada fracionada segundo protocolo de dessensibilização. Resultados: Dos 78 pacientes com história presumida de APO, confirmou-se o diagnóstico em 43 (30M:13F, mediana idade 2,7 a): 30 por TPO, 7 com anafilaxia em menos de 6 meses da vacina, e 6 com reação imediata após ingestão do ovo há menos de 2 meses e IgE específica positiva. Durante o TPO, 12 apresentaram anafilaxia, e os demais (18) apresentaram urticária e/ou angioedema ou vômitos. Todos os testes de puntura (43) foram negativos. ID foi negativo em 37 pacientes, que receberam a dose plena da vacina, sem reações. Apenas 6 apresentaram ID positivo e necessitaram dessensibilização para vacina. Metade desses pacientes (3/6) apresentou reações de hipersensibilidade leves e foi tratada com anti-H1 e/ou corticoide oral. O ID positivo foi significativamente relacionado à reação à vacina (p = 0,0016). Conclusão: Concluiuse ser possível vacinar alérgicos a ovo, com um protocolo seguro, mesmo em paciente comprovadamente anafilático. É necessária uma unidade especializada para sua realização, com capacidade de controlar possíveis situações de risco.

Introduction: The yellow fever vaccine (YFV) is recommended in endemic areas, but represents a risk for egg allergic (EA) patients, as it is cultivated in chicken embryos. Objective: This study aimed to describe the outcomes of YFV in patients with confirmed egg allergy. Methods: A prospective study was conducted in a quaternary hospital, from January to October 2018. EA was diagnosed through oral food challenge (OFC) or recent history of anaphylaxis following egg contact in the past 6 months or allergic reaction in the past 2 months with positive specific immunoglobulin E (IgE). Skin prick testing (SPT) with YFV was performed in all participants. If SPT was negative, an intradermal test (IDT) was performed at 1:100 dilution. If IDT was negative, a full dose of YFV was administered. If SPT was positive, the YFV was administered using a graded-dose protocol. Results: Among 78 patients with prior history of EA, 43 were confirmed (30 male to 13 female, median age of 2.7 years). Thirty patients had a positive OFC, seven reported recent anaphylaxis, and six had reactions in the past 2 months with positive specific IgE. During OFC, 12 patients had anaphylaxis and 18 had urticaria and/or angioedema or vomiting. SPT with YFV was negative in all patients (43). IDT was negative in 37 patients, who received a full dose of YFV, uneventfully. Six patients had a positive IDT and received the YFV in graded doses; half of them had a mild reaction controlled with antihistamines and three patients received the vaccine without reactions. Positive IDT was significantly related to vaccine reaction (p=0.0016). Conclusion: The YFV using a specific protocol was safe even in anaphylactic patients. An appropriate setting is required in order to control possible adverse events.