Reimmunizing patients who had an allergic-like event following immunization


Published Online: December 1, 2016

To prevent anaphylaxis upon re-immunization of patients who had an allergic-like event (ALE) following a prior immunization, the Joint Task Force for Practice Parameters (JTFPP) proposed guidelines for their management based on the likelihood of anaphylaxis (probable or possible) identified through time to symptom onset (≤or >4 hours following immunization) and number of systems involved in the ALE (1 or ≥2 systems).

In an original article published in The Journal of Allergy and Clinical Immunology: In Practice, Zafack and colleagues described the current management of a large series of patients who consulted for suspected vaccine-associated ALEs in a department of allergy in Canada and compared the management to the JTFPP guidelines in order to identify key concepts that may need to be revisited.

In this retrospective study based on chart review, most of the ALEs (98%) following immunization were not suggestive of anaphylaxis but 60% fulfilled the JTFPP criteria of possible or probable anaphylaxis. Most patients were managed as if they had anaphylaxis. There was no significant difference in the frequency of skin testing or re-immunization of patients, regardless of the time to symptom onset or number of systems involved in the ALE. None of the patients re-immunized had anaphylaxis. Recurrence of allergic signs/symptoms mostly occurred in patients with onset of their prior ALE within 1 hour following immunization.

The authors conclude that, in actual practice, most ALEs following immunization are not anaphylactic and should not be managed as such. The definition of anaphylaxis in the JTFPP guidelines seems non-specific and may need to be revisited. The authors propose to restrict skin testing and graded dose re-immunization to patients whose ALE began less than 1 hour (rather than 4 hours) following immunization (compatible with an IgE-mediated reaction) and to those meeting specific clinical criteria for anaphylaxis (regardless of  the time to symptoms onset).

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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