RESUMEN
Background: The mRNA-based COVID-19 vaccine was introduced to the general public in December 2020. Shortly thereafter, safety concerns were raised due to the reporting of allergic reactions. Allergy-related disorders were suspected to be significant risk factors and the excipient polyethylene glycol was suggested to be a robust allergen. Methods: This is a retrospective study analysis. Subjects with putative risk factors for severe allergic reactions to the Pfizer-BioNTech BNT162b2 vaccine were referred for vaccination under observation at the Unit of Allergy and Clinical Immunology. Data was collected for each subject, including demographic details, medical history and previous reactions to any allergen. When appropriate, skin tests were done prior to vaccination. Results: A total of 346 subjects received 623 vaccine doses under observation. The study included patients with various allergy-related disorders (n=290) and those with allergy to a previous COVID-19 vaccine dose (n=56). Both groups showed female predominance (78% and 88%, p=NS). Patients without reactions to previous doses reported more drug allergy (80% vs. 39%, p<0.001) and previous anaphylaxis (64% vs. 14%, p<0.001). There was no difference in sensitivity to other allergens, including polyethylene glycol. Under observation, mild allergic reactions were noted in 13 individuals characterized by female gender (100%), a history of anaphylaxis (69%) and drug allergy (62%). In 7 subjects, allergy was treated with antihistamines while others recovered spontaneously. Conclusion: Our study demonstrates that vaccination under specialist-supervision is a powerful tool for reducing over-diagnosis of systemic reactions and for rapid and reliable collection of vaccine safety data.
RESUMEN
BACKGROUND: In December 2020, the Israeli Ministry of Health launched a national vaccination campaign against SARS-CoV-2. Concomitant sporadic reports on anaphylactic responses in other countries raised safety concerns at the outset of this operation. OBJECTIVE: To characterize reports on allergic reactions to coronavirus disease 2019 vaccines. METHODS: Allergy events were reported by health care professionals throughout the country to Israeli Ministry of Health Division of Epidemiology via a Web-based computerized national vaccine registry. The study period was from December 19, 2020 to September 13, 2021, during which 14,475,979 injections were administered. RESULTS: Allergic reactions were reported in 463 subjects, 99.3% of whom received Pfizer-BioNTech BNTT162B2. The reporting rate was 106 per million in December 2020. From January to May 2021, a reduction was observed to 66, 18, 14, eight, and zero per million, and reporting remained low until September. Mean age of subjects was 48.9 ± 16.7 years (range, 15-96 years) with a female preponderance of 78%. Epinephrine was administered in 34 subjects. Validated immediate allergy was observed in only 37 cases (8%), suggesting 2.5 to 3.3 bona fide reactions per million. In subjects with reactions classified as severe (n = 46), plausible allergy was identified in 36% to 41% of cases. A history of allergy was associated with high false reporting of immediate reactions (83%). Allergic events after the first dose did not compromise adherence to subsequent doses. CONCLUSIONS: Excessive reporting of allergy declined over time and did not affect adherence to vaccination. The existence of previous allergy may affect reporting profiles, but not the occurrence of vaccine allergy.
