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Allergic reactions following COVID-19 vaccination are rare

Published: July 21, 2022

The outbreak of the coronavirus disease 2019 (COVID-19) pandemic triggered global efforts to develop a vaccine against the causative virus, SARS-CoV-2. Consequently, in December 2020 both the United Kingdom and the United States issued emergency authorizations for the mRNA-based Pfizer-BioNTech vaccine designated BNTT162B2. Following the roll-out of the vaccination campaign safety concerns were raised by post-marketing reports of anaphylaxis. These data implied that individuals with a history of allergy could be at increased risk for severe reactions to the new vaccine.

In a recent article published in The Journal of Allergy and Clinical Immunology: In Practice, Anis and colleagues retrospectively analyzed data retrieved from an Israeli national registry of vaccine adverse events. Reports on allergic reactions were submitted by health care professionals to a web-based computerized system operated by the Israeli Ministry of Health. The study covered a period of time from December 2020 to September 2021 during which 14.5 million injections were administered to the general population in a regimen of 3 doses. Allergic reactions were reported in 463 subjects, 99.3% of whom received the Pfizer-BioNTech vaccine. The study population had a mean age of 48.9±16.7 years (range 15-96 years), and a female preponderance of 78%. In December 2020 the reporting rate was 106 allergy events per million. From January to May 2021 a reduction was observed to 66, 18, 14, eight and zero per million and reporting remained low until September. Evaluation of clinical parameters indicated that only 37 cases (8%) constituted real immediate allergy suggesting an estimated actual rate of 2.5 to 3.3 reactions per million throughout most of the study period. A personal medical history of allergy did not increase the risk for true immediate reactions to the vaccine. No role was found for prior sensitization to the excipient polyethylene glycol which had been suspected to be a culprit allergen. Intriguingly, reporting of allergic events after the first dose did not compromise adherence to subsequent doses.  

This study offers a unique overview of allergic reactions to the COVID-19 vaccine on a national level and relies on a large number of injections. The investigators show that reporting of allergic responses declined rapidly over time and that genuine allergy was rare. Furthermore, the vaccine was found to be safe for individuals with a history of allergy, contrary to some post-marketing reports. It is, therefore, concluded that the Pfizer-BioNTech does not appear to be more allergenic than other vaccines that have been traditionally used for different infections.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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