GPs are being advised to refer patients with suspected anaphylactic reaction to influenza vaccine to an allergist after research found almost nine in 10 are being misclassified as allergic to the injection.

The high number of wrong classifications was likely because it was difficult to distinguish between true anaphylaxis and a plethora of immunisation stress-related responses, said lead researcher Dr Beau Carr, from Monash Health in Melbourne.

“Conditions that mimic vaccine anaphylaxis are more common than anaphylaxis itself and our findings suggest that influenza vaccine allergy may be overdiagnosed,” Dr Carr and colleagues wrote in a research letter in the Medical Journal of Australia on Monday.

The research team reviewed the clinical responses of all adults diagnosed with influenza vaccine allergy at Monash Health’s vaccine allergy service from 1 April 2017 to 31 August 2021.