Possible allergic reaction should not delay COVID-19 vaccination

People who had an allergic response to the first dose of COVID-19 vaccination or who believe they will have an allergy to vaccination should not let their worries delay getting vaccinated — as most of them can still be fully vaccinated safely, suggest studies presented at ACAAI 2021. 

“Individuals are often asked if they have a poly-ethylene glycol [PEG] allergy prior to receiving an mRNA COVID-19 vaccine,” said lead author Dr Mitchell Pitlick of Mayo Clinic, Rochester, Minnesota, US. “An affirmative answer may delay vaccination, which may not always be necessary.”

Pitlick and team conducted a retrospective review of 100 participants with known PEG allergy who presented to a COVID-19 vaccination clinic. The most common PEG reaction reported was gastrointestinal intolerance, reported by 38 participants; followed by cutaneous symptoms in 29 individuals. Other non-allergic symptoms were listed by 28 participants. Most of the PEG allergies cases (n=84) were attributed to oral PEG preparations. [ACAAI 2021, abstract P006]

“Our cohort consisted primarily of patients who experienced gastrointestinal intolerance with an oral PEG preparation,” said study co-author Dr Miguel Park, also from Mayo Clinic Rochester. “This is unlikely to represent a true PEG allergy and shouldn’t delay vaccination. It’s important to recognize true vs non-allergic reactions.”

Among the participants, 64 received the Pfizer-BioNTech’s BNT162b2 vaccine, 33 were given Moderna’s mRNA-1273 vaccine, and the remaining three had the Janssen’s Ad26.CoV2.S vaccine.

“Despite their previous reactions to PEG in oral PEG preparations, all 100 patients tolerated the full vaccine series without allergic symptoms,” reported Pitlick. “This review demonstrates that patients with a prior adverse reaction to PEG-containing products can tolerate mRNA COVID-19 vaccines.”

“Given PEG’s potential role as a culprit in mRNA COVID-19 vaccine reactions, it is still important to recognize non-allergic reactions. If there is any question, use of a non-PEG containing vaccine or rapid e-consultation with an allergist may be appropriate to facilitate timely vaccination,” he advised.

In another study, researchers analysed medical records of 25 participants who were referred to an allergist for adverse events following immunization (AEFI) after receiving their first dose of mRNA vaccine, of which 23 showed adverse symptoms. [ACAAI 2021, abstract A001]

Of the 16 individuals who experienced immediate reactions following vaccination, six underwent skin testing, which turned out negative results. Following directed testing or other assessments, 15 individuals underwent a vaccine challenge — and the post-vaccine symptoms were all mild with no unexpected reactions. 

Of the remaining eight participants with adverse symptoms, only two were advised not to continue with the second vaccine dose.

“This study shows that with appropriate specialty evaluation by an allergist, the majority of patients with AEFI can tolerate the second dose of the mRNA vaccine to complete the series,” said presenting author Dr Benjamin St Clair of Tripler Army Medical Center in Honolulu, Hawaii, US.

“AEFI can lead to vaccine hesitancy and unnecessary susceptibility to disease,” he added. “This study provides an approach on how to evaluate and manage AEFI during a pandemic, demonstrate the limitation of current testing, and provide insight on how to counsel patients considering future doses.”