Some Flu Vaccine Reactions Could Be Misdiagnosed As Anaphylaxis

Some Flu Vaccine Reactions Could Be Misdiagnosed As Anaphylaxis

According to the authors of a research letter published by the Australian Medical Journal.

The researchers reviewed the clinical records of all adults (18 years or older) with diagnoses of influenza vaccine allergies who attended Monash Health’s Adult Vaccine Allergy Service from April 1, 2017 to August 31, 2021.

“The index reactions of seven of the 49 participants met the Brighton criteria for anaphylaxis; the most common symptoms were dermatological (70%) or respiratory (57%) reactions,” the researchers report.

“After split doses (10 participants) or full doses (39 participants), 20 people had symptoms consistent with vaccine stress-related responses, but none met the Brighton criteria for anaphylaxis.

“Thirteen of the 20 were de-labeled because their symptoms were mild; the other seven were also removed from the label after challenge with a different influenza vaccine the following year.

“As it can be difficult to distinguish anaphylaxis associated with the influenza vaccine – estimated by a US study to affect 1.35 people per million doses – from the more numerous responses related to vaccine stress – affecting 4-7% of vaccinees flu – these can be misdiagnosed as allergies,” wrote the authors, led by Dr. Beau Carr, of Monash Health.

“It is difficult to distinguish between anaphylaxis and an acute stress response in acute healthcare, despite World Health Organization guidelines,” Carr and colleagues concluded.

“We recommend that reactions be treated as allergic if clinically suspected, but also that the patient be promptly referred to an allergist for further evaluation. It will probably be safe to remove the label from many patients because their reactions do not meet the criteria for anaphylaxis.

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