COVID-19 mRNA vaccine allergy

Abstract

Purpose of review A known history of a severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine is the only contraindication to coronavirus disease 2019 (COVID-19) mRNA vaccination. It is important for pediatricians to understand the likelihood of an allergic reaction to COVID-19 mRNA vaccines, including its excipients. Recent findings Episodes concerning for anaphylaxis were immediately reported following early administration of COVID-19 mRNA vaccines to adults. Although allergic type symptoms were reported equally in recipients of placebos and test vaccines in phase 3 clinical trials, post-authorization prospective studies state that 0.2–2% of vaccine recipients have experienced allergic reactions. Subsequent allergy testing of affected individuals has focused largely on evaluation of allergic sensitization to a novel vaccine excipient, polyethylene glycol (PEG). PEG is a polymer incorporated in numerous pharmaceutical products because of its favorable, inert properties. The results of allergy testing in adults to date indicate that IgE mediated anaphylaxis to PEG allergy is rarely identified after COVID-19 mRNA vaccine reactions. Numerous individuals with presumed anaphylaxis have tolerated a second vaccine after evaluation and testing by an allergist, suggesting either misdiagnosis or a novel immune mechanism. Summary Confirmed anaphylactic reactions to COVID-19 mRNA vaccines are rare, likely due to a lack of preexisting IgE against the vaccine components, including PEG.

The prevalence of adverse reactions among individuals with three-dose COVID-19 vaccination

“…Individuals with higher education levels may pay more attention to their physical condition and be more sensitive to adverse reactions [27] . The prevalence (95% CI) of anaphylaxis or hospitalization with the three doses was 0.39% (0.21%–0.66%), 0.24% (0.10%–0.47%), and 0.33% (0.16%–0.59%) in our study, which was similar to previous studies [25] , [28] , [29] . Fever, as a measurable objective indicator, is often a concern after vaccination.…”

Ethical Considerations Surrounding Employment Mandated Coronavirus Disease 2019 Vaccination and Allergy Skin Testing for the Coronavirus Disease 2019 Vaccine

“…Previous studies indicate confirmed anaphylaxis caused by COVID-19 vaccines is rare, 15,16 likely because of a lack of preexisting immunoglobulin E antibodies against the novel COVID-19 mRNA vaccine excipient PEG and other vaccine components 17 . Similarly, a cohort study found that 98% of a group of highly allergic individuals had no allergic reaction after COVID immunization, 1% had mild allergic responses, and only 0.7% had anaphylactic reactions 18 …”

Skin Testing and Basophil Activation Testing Is Useful for Assessing Immediate Reactions to Polyethylene Glycol-Containing Vaccines

“…A negative ST does not exclude anaphylaxis, as non-IgE mechanisms such as CAPRA may be implicated. Administration of future vaccines with negative ST warrants consideration of precautions such as administration of antihistamines or incremental or staged doses of the vaccine [ 33 ].…”