Table 2.

Potential risk factors for COVID-19 vaccine-related allergy as reported in post-marketing surveillance

Authors	Reported potential risk factors for COVID-19 vaccine-related allergy
Shimabukuro et al. (2021) [30]	Seventeen (81%) of 21 patients with anaphylaxis with Pfizer-BioNTech COVID-19 vaccine had a documented history of allergies (e.g., to drugs or medical products, foods, and insect stings) Seven (33%) had an episode of anaphylaxis in the past, including one after receipt of rabies vaccine and another after receipt of influenza A(H1N1) vaccine
Shimabukuro et al. (2021) [7]	Twenty-one (32%) of the 66 case reports noted a prior episode of anaphylaxis from other exposures: vaccines (rabies, influenza A[H1N1], seasonal influenza, unspecified), contrast media, unspecified infusions, sulfa drugs, penicillin, prochlorperazine, latex, walnuts, unspecified tree nuts, jellyfish stings and unspecified exposures
Klein et al. (2021) [12] Iguchi et al. (2021) [16] Shavit et al. (2021) [17] Blumenthal et al. (2021) [18] Shimabukuro et al. (2021) [30] Risma et al. (2021) [37]	All these studies reported a striking prevalence of COVID-19 vaccine-related allergic reactions in females
Risma et al. (2021) [37]	Atopic individuals also appear to be overrepresented in those suffering anaphylaxes to the COVID-19 mRNA vaccines Another host factor that may impact the likelihood of anaphylaxis is stress
Caminati et al. (2021) [43]	Only mild reactions, mainly local, after the administration of both doses, in patients with severe asthma Asthma remained under control between the two doses and quality of life improved
Rojas-Pérez-Ezquerra et al. (2021) [44]	The COVID-19 vaccination, carried out in a specialized setting, was also well tolerated in patients with severe allergic conditions, such as hymenoptera, food, and drug allergy The only reaction recorded was a mild immediate reaction in a 43-year-old woman with a personal history of severe asthma
Fijen et al. (2021) [45]	Good tolerability was reported in a population of 63 patients suffering from hereditary angioedema. After vaccination, 11 attacks were reported out of 111 administrations. All these attacks were mild, and patients recovered within 2 days