Canadian Immunization Guide: "Anaphylaxis and other acute reactions following vaccination" chapter update

The Canadian Immunization Guide (CIG) is a comprehensive resource on immunization for health professionals and vaccine program decision-makers. It is developed based on the evidence-based recommendations of the National Advisory Committee on Immunization (NACI). The NACI Vaccine Safety Working Group (VSWG) is comprised of NACI members, liaison members and external experts. The World Allergy Organization now recommends that antihistamines should not be used in the initial treatment of anaphylaxis. The update of the chapter was also used to provide further information and clarity to several tables in the chapter.

In updating the CIG anaphylaxis guidance, VSWG conducted an environmental scan, a review of relevant literature and consulted international and Canadian experts and professional societies.

The use of diphenhydramine hydrochloride as adjunctive treatment in the management of anaphylaxis in a community setting is no longer recommended. Other notable changes made to the chapter include the following: 1) retitled: "Anaphylaxis and other acute reactions following vaccination"; 2) inclusion of new tables: "Key distinguishing features of anaphylaxis and vasovagal syncope" and "Signs and symptoms of anaphylaxis"; and 3) updated tables: "Anaphylaxis management kit: recommended items" and "Dosage of intramuscular EPINEPHrine 1:1000 (1 mg/mL) solution, by age or weight".

The updated CIG chapter provides healthcare providers with further clarity in recognizing and managing anaphylaxis in community settings. The updated intramuscular epinephrine dosage table will aid in optimal epinephrine administration, while the revised guidance against the use of diphenhydramine hydrochloride will prevent its unnecessary stockpiling in preparation for potential mass vaccination clinics related to the coronavirus disease 2019 pandemic.