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Immediate hypersensitivity to COVID-19 vaccines: Focus on biological diagnosis
Pascale Nicaise-Roland1,2, Vanessa Granger1,3, Angèle Soria4,5
1Service d'Immunologie Biologique, Hôpital Bichat, DMU BIOGÉM, APHP, Paris, France.
Abstract:
Soon after the release of the new anti-COVID mRNA vaccines, reports came in from the US and the UK of anaphylactic reactions. Fueled by the necessary caution toward these new vaccine platforms, these reports had a great impact and were largely commented upon in the scientific literature and global media. The current estimated frequency is of 5 cases per million doses. Very little biological data are presented in the literature to support the anaphylaxis diagnosis in these patients in addition to skin tests. Allergic reactions to vaccines are rare and mostly due to vaccine excipient. Therefore, the poly-ethylene-glycol (PEG) present in both mRNA formulation, and already known to be immunogenic, was soon suspected to be the potential culprit. Several hypersensitivity mechanisms to PEG or to other vaccine components can be suspected, even if the classical IgE-dependent anaphylaxis seems to be one of the most plausible candidates. In the early 2022, the international guidelines recommended to perform skin prick tests and basophil activation tests (BAT) in people experiencing allergic reaction to the first dose of COVID-19 vaccine or with a history of PEG allergy. The aim of this review is to discuss the main potential mechanisms of immediate allergy to COVID19 vaccines based on published data, together with the various techniques used to confirm or not sensitization to one component.
Insights
Anaphylactic reactions to mRNA COVID-19 vaccines, estimated at 5 cases per million, are rare. Poly-ethylene-glycol (PEG) is suspected due to its immunogenic properties and presence in mRNA formulations, with IgE-dependent anaphylaxis as a likely mechanism.
Area of Science:
- Immunology
- Vaccinology
- Allergology
Background:
- Reports of anaphylaxis following mRNA COVID-19 vaccination emerged globally.
- These reactions, though infrequent (5 per million doses), prompted significant scientific and media attention.
- Allergic vaccine reactions are typically linked to excipients, with poly-ethylene-glycol (PEG) identified as a potential trigger in mRNA vaccines.
Purpose of the Study:
- To review potential mechanisms of immediate allergic reactions to mRNA COVID-19 vaccines.
- To discuss diagnostic techniques for confirming sensitization to vaccine components.
Main Methods:
- Review of published literature on anaphylaxis and mRNA vaccines.
- Discussion of diagnostic methods including skin prick tests and basophil activation tests (BAT).
Main Results:
- Poly-ethylene-glycol (PEG) is a suspected culprit due to its immunogenicity and presence in mRNA vaccine formulations.
- IgE-dependent anaphylaxis is considered a plausible hypersensitivity mechanism.
- International guidelines now recommend specific allergy testing for individuals with a history of reaction or PEG allergy.
Conclusions:
- Immediate allergic reactions to mRNA COVID-19 vaccines warrant investigation into hypersensitivity mechanisms.
- Poly-ethylene-glycol (PEG) is a key suspect, necessitating further research into its role.
- Appropriate diagnostic testing is crucial for managing and understanding these rare vaccine-induced allergic events.
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