International Journal of Clinical Case Reports, 2025, Vol.15, No.6, 271-282 http://medscipublisher.com/index.php/ijccr 273 2.3 The impact of vaccination settings, standardized procedures and observation periods on risks Standardizing the environment and operation procedures for vaccination, as well as attaching importance to the observation period after vaccination, are the keys to reducing the risk and serious harm of anaphylactic shock. The analysis of the management of vaccination sites shows that as long as each place is fully prepared and can identify and handle allergy emergencies in a timely manner, there is no significant difference in the risk of death or disability due to vaccine allergy among medical clinics, pharmacies and public health service points (Klosko et al., 2023). This clearly indicates that all vaccination sites must be staffed with professionally trained personnel, have clear emergency plans, and be equipped with adrenaline and emergency resuscitation devices that can be obtained immediately (Luxi et al., 2022). The standard procedure includes a thorough screening of allergy history before vaccination and strict adherence to the recommended post-vaccination observation period, usually 15 to 30 minutes. For those who have had severe allergic reactions, the observation time can be appropriately extended to 60 minutes (Wentrys and Stopyra, 2022). Studies have found that most allergic reactions occur within the first 30 minutes after vaccination, which further demonstrates the importance of post-vaccination observation. The implementation of the above measures can significantly reduce serious consequences and deaths, making immunization work safer in various vaccination Settings (Klosko et al., 2023). 3 The Basic Immunological Mechanism of Anaphylactic Shock 3.1 igE-mediated type I hypersensitivity reaction and rapid response after re-exposure The classic mechanism of anaphylactic shock is IgE-mediated type I hypersensitivity reaction: When exposed to allergens such as vaccine components or excipients for the first time, under the action of Th2 cytokines (such as IL-4, IL-5), B cells produce allergen-specific IgE, which binds to high-affinity FcεRI receptors on the surface of mast cells and basophils, putting them in an sensitized state (Bellomo et al., 2021; Hung et al., 2022). When exposed again, allergens cross-link with IgE on the cell surface, rapidly triggering a signal transduction cascade, causing mast cell degranulation and the release of a large amount of inflammatory mediators, which can lead to typical acute allergic manifestations within minutes (Nguyen et al., 2021; Kounis et al., 2021; Hung et al., 2022). Ige-mediated allergic reactions can present in various ways. Mild cases may include urticaria and skin edema, while severe ones can lead to tracheal spasm, low blood pressure and even heart failure. To determine this reaction, it is usually necessary to look at the results of specific IgE tests and whether the serum trypsin level is elevated-this can indicate whether mast cells have been activated ( Kounis et al., 2021; Ebo et al., 2022). However, not all shock caused by vaccine allergies is related to this pathway. It is also necessary to consider whether other immunization methods are at play (Nguyen et al., 2021;Hung et al., 2022; Worm et al., 2025). 3.2 Degranulation of mast cells and basophils and release of inflammatory mediators Whether through the IgE pathway or not, the rapid degranulation of mast cells and basophils is the core event of anaphylactic shock. This non-cytolysis process releases pre-formed histamine, trypsin, heparin and chymotrypsin in the granules, as well as newly synthesized leukotrienes, prostaglandins and platelet-activating factor (PAF) into the extracellular space (Nguyen et al., 2021). These mediators drive clinical manifestations such as airway edema, bronchoconstriction, hypotension and even shock by increasing vascular permeability, inducing smooth muscle contraction and vasodilation, and recruiting more inflammatory cells (Nguyen et al., 2021). Recent studies have shown that different activation signals can induce different mediator release patterns and intracellular pathways (such as calcium mobilization and inflammasome-related pathways) to be differentially initiated, thereby affecting the severity of allergic reactions and the spectrum of target organ involvement. This provides an important theoretical basis for the development of targeted interventions for key links to prevent or alleviate severe allergic reactions (Mencarelli et al., 2024). 3.3 The role of non-IgE-mediated reactions In addition to the IgE-mediated mode of action, it is also crucial in vaccine-induced anaphylactic shock and non-igE-mediated "pseudo-allergic" reactions. This type of reaction does not require specific IgE and can directly
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