Investigation of Adverse Events Following Immunization (AEFIs) At a Workplace Influenza Vaccination Clinic: From Disinfectant to Dermatitis

Background: Workplace immunization clinics provide a unique opportunity for AEFI investigations since cohorts of vaccinated individuals can readily be followed-up. In Fall 2010, Toronto Public Health (TPH) received numerous reports of AEFIs involving localized rashes and/or swelling that were associated with a one-day workplace influenza vaccine clinic.

Objectives: To investigate the nature and contributing factor(s) of the AEFIs.

Methods: A retrospective review was conducted using information from the agency that administered the vaccines, the workplace, AEFI reports, and Integrated Public Health Information System (iPHIS) records. Reported AEFIs were assigned a case definition based on Brighton Collaboration criteria. Descriptive statistics were analyzed using Microsoft® Excel.

Results: At the clinic, 3 nurses immunized 253 clients from 9:00-16:30. At approximately 13:00, two nurses depleted their alcohol swab supply, and began using solution from a bottle labeled "alcohol" as a disinfectant. No clients immunized prior to the 13:00-13:30 period experienced an AEFI. Twenty-four of the 86 clients vaccinated during or after this period reported an AEFI. All AEFIs occurred that day, with the majority arising within ~30 minutes of immunization. Ninety-six percent of cases met a case definition of "rash including mucosal involvement," or "swelling at or near injection site," or both. Of these clients, the age range was 15-63 years, and ≥21% visited an ER. The "alcohol" solution was analyzed and contained 66% isopropanol, 15% acetone and other trace volatile organic compounds. The clients likely experienced irritant contact dermatitis (ICD), as supported by the nature, rapid onset, and high prevalence of the AEFIs, and the fact that agents similar to the solution used are known to cause ICD.

Conclusions: The AEFIs likely arose from the use of the "alcohol" solution containing acetone. Consistent adherence to vaccine administration protocols is imperative to reduce the likelihood of AEFIs and maintain public confidence in vaccine safety.