International Journal of Clinical Case Reports, 2025, Vol.15, No.6, 271-282 http://medscipublisher.com/index.php/ijccr 271 Research Insight Open Access Analysis of the Immunological Mechanisms of Anaphylactic Shock Following Vaccination and Recommendations for Prevention Jianmin Liu Sinovac Biotech Co., Ltd., Haidian, 100193, Beijing, China Corresponding email: Jianminliu@sinovac.com International Journal of Clinical Case Reports 2025, Vol.15, No.6 doi: 10.5376/ijccr.2025.15.0028 Received: 15 Sep., 2025 Accepted: 17 Oct., 2025 Published: 30 Nov., 2025 Copyright © 2025 Liu, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Liu J.M., 2025, Analysis of the immunological mechanisms of anaphylactic shock following vaccination and recommendations for prevention, International Journal of Clinical Case Reports, 15(6): 271-282 (doi: 10.5376/ijccr.2025.15.0028) Abstract This study explored anaphylactic shock after vaccination, its epidemiological characteristics, key immunological mechanisms, and prevention and control strategies. It was pointed out that the overall incidence of this event is extremely low, but rare cases can still be seen in influenza, MMR, chickenpox, and mRNA COVID-19 vaccines. The high-risk groups mainly include those with a history of severe allergies, atopic constitution, and those with concurrent chronic diseases. In immunology, it involves not only the classic IgE-mediated type I hypersensitivity reaction but also non-ige mechanisms such as CARPA and MRGPRX2-mediated mast cell activation. The sensitizing components can come from the vaccine antigen itself or from excipients and novel adjuvants such as gelatin, protein residues, PEG, sorbate 80 and lipid nanoparticles. The article emphasizes that most cases have an acute onset within minutes to half an hour after vaccination and involve the skin, respiratory and circulatory systems. Risk assessment and stratification should be conducted before vaccination. High-risk groups should choose a vaccination environment with resuscitation capacity and appropriately extend the observation period. Standardized emergency procedures, the preferred use of epinephrine and continuous pharmacovigilance should be followed. On the premise of affirming the significant public health benefits of vaccines, further enhance the safety and public trust of new vaccine platforms. Keywords Vaccination; Anaphylactic shock; IgE and non-igE-mediated mechanisms; Vaccine excipients; Risk assessment and prevention 1 Introduction Vaccination is an extremely valuable achievement in the field of public health. It can significantly reduce the harm caused by infectious diseases and save the lives of millions of people around the world. For this reason, diseases such as polio, measles and influenza have either been almost eradicated or effectively controlled. When the COVID-19 pandemic broke out on a large scale in 2020, the rapid development and promotion of vaccines further demonstrated their significant role in controlling the number of cases and deaths caused by novel pathogens (Risma et al., 2021). As the scope of vaccination continues to expand, the safety and efficacy of vaccines remain the key to maintaining public trust and achieving the high vaccination rate required for herd immunity (Tanno et al., 2021; Pennisi et al., 2025). However, like all medical treatments, the occurrence of a few adverse reactions may still seriously affect the public's thoughts and willingness to get vaccinated. Among the various adverse reactions to vaccines, anaphylactic shock, although rare, is extremely harmful and requires special attention from medical staff and public health departments. It occurs rapidly and may cause fatal problems in the airways, respiratory or circulatory systems, usually requiring immediate medical treatment (Tanno et al., 2021). The probability of allergic reactions after vaccination is actually very low. According to statistics, for most vaccines, there are only about 1 to 2 cases per million doses, and the fatality rate is even lower. However, precisely because of its significant harm, it is necessary to establish a complete monitoring system and formulate timely identification and handling plans. Only in this way can patient safety be guaranteed and the public continue to trust the vaccination work (Pennisi et al., 2025). It should be noted that allergic reactions can occur regardless of whether there is a history of allergies or not. This involves both IGE-mediated and non-igE-mediated modes of action, making risk assessment and prevention work more complex (Barth et al., 2023). The emergence of new types of vaccines such as mRNA vaccines and vector vaccines has also forced people to pay renewed attention to
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