Potential mechanisms of anaphylaxis to COVID-19 mRNA vaccines.

Anaphylaxis to vaccines is historically a rare event. The coronavirus disease 2019 pandemic drove the need for rapid vaccine production applying a novel antigen delivery system: messenger RNA vaccines packaged in lipid nanoparticles. Unexpectedly, public vaccine administration led to a small number of severe allergic reactions, with resultant substantial public concern, especially within atopic individuals. We reviewed the constituents of the messenger RNA lipid nanoparticle vaccine and considered several contributors to these reactions: (1) contact system activation by nucleic acid, (2) complement recognition of the vaccine-activating allergic effector cells, (3) preexisting antibody recognition of polyethylene glycol, a lipid nanoparticle surface hydrophilic polymer, and (4) direct mast cell activation, coupled with potential genetic or environmental predispositions to hypersensitivity. Unfortunately, measurement of anti-polyethylene glycol antibodies in vitro is not clinically available, and the predictive value of skin testing to polyethylene glycol components as a coronavirus disease 2019 messenger RNA vaccine-specific anaphylaxis marker is unknown. Even less is known regarding the applicability of vaccine use for testing (in vitro/vivo) to ascertain pathogenesis or predict reactivity risk. Expedient and thorough research-based evaluation of patients who have suffered anaphylactic vaccine reactions and prospective clinical trials in putative at-risk individuals are needed to address these concerns during a public health crisis.

Pediatric eosinophilic esophagitis: the Vanderbilt experience.

BACKGROUND: Eosinophilic esophagitis (EoE) is a chronic allergic disease of the esophagus unresponsive to treatment with proton pump inhibitors. A combination of immediate, IgE-mediated and delayed, and non-IgE-mediated immune reactions to foods and aeroallergens is thought to contribute to disease pathogenesis. Optimal methods to assess for food allergen sensitization have been debated. Patients with EoE often have comorbid atopic diseases. OBJECTIVE: To characterize pediatric patients diagnosed with EoE at a single institution within the southeastern United States. METHODS: A retrospective study was conducted to evaluate 211 pediatric patients with EoE at Vanderbilt University Medical Center. Aeroallergen and food sensitization profiles obtained by skin prick testing (SPT), atopy patch testing (APT), and history of associated atopic diseases were analyzed. RESULTS: Older patients with EoE showed greater aeroallergen sensitization; the most common allergens were pollens and dust mite. Younger patients showed greater sensitization to foods by SPT and APT. The most common foods identified by SPT were peanut, egg, and soy. The most common foods identified by APT were potato, pork, and wheat. Comorbid atopic disease was common. Patients with atopic dermatitis did not show significantly greater sensitization to foods by SPT or APT compared with patients without atopic dermatitis. CONCLUSION: In pediatric patients with EoE, sensitization to aeroallergens increases with age, whereas sensitization to foods decreases with age. Concomitant atopic disease is common. APT is useful to identify additional food allergens not detected by SPT. A history of atopic dermatitis does not appear to be associated with nonspecific positivity by SPT or APT.

Evaluation of association of anti-PEG antibodies with anaphylaxis after mRNA COVID-19 vaccination.

BACKGROUND: The mechanism for anaphylaxis following mRNA COVID-19 vaccination has been widely debated; understanding this serious adverse event is important for future vaccines of similar design. A mechanism proposed is type I hypersensitivity (i.e., IgE-mediated mast cell degranulation) to polyethylene glycol (PEG). Using an assay that, uniquely, had been previously assessed in patients with anaphylaxis to PEG, our objective was to compare anti-PEG IgE in serum from mRNA COVID-19 vaccine anaphylaxis case-patients and persons vaccinated without allergic reactions. Secondarily, we compared anti-PEG IgG and IgM to assess alternative mechanisms. METHODS: Selected anaphylaxis case-patients reported to U.S. Vaccine Adverse Event Reporting System December 14, 2020-March 25, 2021 were invited to provide a serum sample. mRNA COVID-19 vaccine study participants with residual serum and no allergic reaction post-vaccination ("controls") were frequency matched to cases 3:1 on vaccine and dose number, sex and 10-year age category. Anti-PEG IgE was measured using a dual cytometric bead assay (DCBA). Anti-PEG IgG and IgM were measured using two different assays: DCBA and a PEGylated-polystyrene bead assay. Laboratorians were blinded to case/control status. RESULTS: All 20 case-patients were women; 17 had anaphylaxis after dose 1, 3 after dose 2. Thirteen (65 %) were hospitalized and 7 (35 %) were intubated. Time from vaccination to serum collection was longer for case-patients vs controls (post-dose 1: median 105 vs 21 days). Among Moderna recipients, anti-PEG IgE was detected in 1 of 10 (10 %) case-patients vs 8 of 30 (27 %) controls (p = 0.40); among Pfizer-BioNTech recipients, it was detected in 0 of 10 case-patients (0 %) vs 1 of 30 (3 %) controls (p >n 0.99). Anti-PEG IgE quantitative signals followed this same pattern. Neither anti-PEG IgG nor IgM was associated with case status with both assay formats. CONCLUSION: Our results support that anti-PEG IgE is not a predominant mechanism for anaphylaxis post-mRNA COVID-19 vaccination.

Diverticulitis in a young man with hyper-IgE syndrome.

Autosomal dominant hyperimmunoglobulin E syndrome (HIES, or Job syndrome) is a rare primary immunodeficiency characterized by elevated immunoglobulin E (IgE), eosinophilia, recurrent skin and pulmonary infections, dermatitis, and connective tissue and skeletal abnormalities. A 26-year-old male with known HIES presented with abdominal pain and diarrhea. Imaging showed sigmoid diverticulitis without abscess or perforation. Conservative management with antibiotics failed, and he developed a peridiverticular abscess, which was percutaneously drained with plans for elective resection. He returned four days later with progression of his diverticulitis, requiring partial colectomy with primary anastomosis. To our knowledge, this is the first case of diverticulitis in HIES. Diverticulitis is rare in younger individuals, raising the possibility that the connective tissue abnormalities of HIES patients may predispose them to colonic diverticula. Although the majority of complications are sinopulmonary and skin infections, diverticulitis should be considered in the differential of intra-abdominal processes in HIES.

International Consensus (ICON): allergic reactions to vaccines.

BACKGROUND: Routine immunization, one of the most effective public health interventions, has effectively reduced death and morbidity due to a variety of infectious diseases. However, allergic reactions to vaccines occur very rarely and can be life threatening. Given the large numbers of vaccines administered worldwide, there is a need for an international consensus regarding the evaluation and management of allergic reactions to vaccines. METHODS: Following a review of the literature, and with the active participation of representatives from the World Allergy Organization (WAO), the European Academy of Allergy and Clinical Immunology (EAACI), the American Academy of Allergy, Asthma, and Immunology (AAAAI), and the American College of Allergy, Asthma, and Immunology (ACAAI), the final committee was formed with the purpose of having members who represented a wide-range of countries, had previously worked on vaccine safety, and included both allergist/immunologists as well as vaccinologists. RESULTS: Consensus was reached on a variety of topics, including: definition of immediate allergic reactions, including anaphylaxis, approaches to distinguish association from causality, approaches to patients with a history of an allergic reaction to a previous vaccine, and approaches to patients with a history of an allergic reaction to components of vaccines. CONCLUSIONS: This document provides comprehensive and internationally accepted guidelines and access to on-line documents to help practitioners around the world identify allergic reactions following immunization. It also provides a framework for the evaluation and further management of patients who present either following an allergic reaction to a vaccine or with a history of allergy to a component of vaccines.

Eosinophilic esophagitis: an allergist's approach.

OBJECTIVE: To enhance the recognition of eosinophilic esophagitis by reviewing the presentation, diagnosis, and pathogenesis and then summarizing the epidemiology and treatment options. DATA SOURCES: MEDLINE was searched for articles using the keywords esophagitis and either allergy or eosinophil. Additional sources include searches limited to therapy, including corticosteroids and leukotrienes, and those limited to review articles, including chemokines and cytokines, from January 1990 to April 2006. All searches were limited to the English language. STUDY SELECTION: The authors selected relevant and current sources for inclusion in this review. RESULTS: Eosinophilic esophagitis is a diagnosis made by identifying 20 to 24 eosinophils per high-power field on examination of esophageal biopsy specimens. In recent years, a marked increase in incidence worldwide may have occurred. Although the pathogenesis is still unclear, therapy involves the use of corticosteroids and appropriate dietary elimination. CONCLUSION: Patients with atopy, especially males, who present with dysphagia, reflux symptoms, vomiting, abdominal pain, or failure to thrive should be considered for endoscopy to establish the diagnosis of eosinophilic esophagitis.