COVID-19 vaccines are based on different vaccine platforms based on nucleic acids, artificial vectors or recombinant viruses, virus protein subunits or disabled (live attenuated or inactivated) viruses.  Innovative platforms (Pfizer-BioNtech, Moderna and Curevac CvnCoV) are based on messenger ribonucleic acid (mRNA) encoding spike protein that is encapsulated in nanoparticles containing lipids and polyethylene glycol (PEG) 2000. PEG are suspected to be responsible in IgE mediated reactions and also involved in mast cell degranulation (CARPA mechanism). A direct activation by nanoparticle structures can also be responsible of mast cell degranulation. Other vaccines, except disabled ones, contain polysorbates supposed to cross react with PEG. EAACI has published two recommendations for managing hypersensitivity due to these vaccines. However, new data is continuously published, so it will be important to analyze all data in order to better know the mechanisms involved in these adverse events and propose a specific management for each of them.
Regarding diagnosis it is critical to determine the value of drug skin tests and in vitro tests. The role of drug provocation test in the allergological work-up need to be established. All these is important not only to perform an accurate diagnosis but also to avoid a false allergy label, that will avoid patients receiving such as important treatment. It will be important to confirm that further injections are usually well tolerated with or without antihistamines or topical corticosteroids. This analysis will also be important for future development of PEG nanoparticles platforms for other vaccines and innovative targeted therapeutics. Allergists will have to manage patients with intolerance to these innovative drugs.
Regarding management, through an online questionnaire for EAACI members and literature analysis,
we will recommend approaches to patients with confirmed allergy such as
desensitization procedure or fractionated injections. The analysis of efficacy
of these procedures needs to be done.

Chair: Annick Barbaud
Secretary: Maria Torres