Allergic adverse events following 2015 seasonal influenza vaccine, Victoria, Australia

Abstract

Australia was alerted to a possible increase in allergy-related adverse events following immunisation (AEFI) with 2015 seasonal trivalent influenza vaccines (TIV) by the Victorian state vaccine safety service, SAEFVIC. We describe SAEFVIC’s initial investigation and upon conclusion of the 2015 influenza vaccination programme, to define the signal event and implications for vaccine programmes. Allergy-related AEFI were defined as anaphylaxis, angioedema, urticaria or generalised allergic reaction. Investigations compared 2015 TIV AEFI reports to previous years as proportions and reporting risk (RR) per 100,000, stratified by influenza vaccine brand. The initial investigation showed an increased proportion of allergy-related AEFI compared with 2014 (25% vs 12%), predominantly in adults, with insufficient clinical severity to alter the programme risk-benefit. While overall TIV AEFI RR in 2015 was similar to previous years (RR: 1.07, 95% confidence interval (CI): 0.88–1.29), we identified a near-doubling RR for allergy-related AEFI in 2015 (RR: 1.78, 95% CI: 1.14­– 2.80) from 2011 to 2014 with no difference by vaccine brand or severity increase identified. This increase in generalised allergy-related AEFI, across all used vaccine brands, supports evidence of variable reactogenicity arising from influenza vaccine strain variations. This investigation underlines the importance of effective seasonal influenza vaccine pharmacovigilance.

Active surveillance of 2017 seasonal influenza vaccine safety: an observational cohort study of individuals aged 6 months and older in Australia

“…In Australia, these limitations have especially affected passive influenza vaccine safety surveillance, and have led to previous difficulty in interpreting early or potential vaccine safety signals. 44 In this context, AusVaxSafety provides important data to ensure confidence in the safety of vaccines in use in large populations in near real time.…”

Challenges in implementing yearly enhanced safety surveillance of influenza vaccination in Europe: lessons learned and future perspectives

“…An investigation identified a relative risk for allergy-related AEFI of 2.4 per 100,000 vaccine doses in 2015; almost double that seen in 2011−2014 (relative risk of 1.3/ 100,000), with no difference between vaccine brands. 38 These findings highlighted the potential for changes in reactogenicity following an update of the influenza vaccine strains, emphasising the importance of continued pharmacovigilance. 38 WAVSS Established in 2011 (built upon the SAEFVIC model) to monitor vaccine safety.…”

“…38 These findings highlighted the potential for changes in reactogenicity following an update of the influenza vaccine strains, emphasising the importance of continued pharmacovigilance. 38 WAVSS Established in 2011 (built upon the SAEFVIC model) to monitor vaccine safety. 39 Enables regional voluntary reporting of suspected AEFI from both the public and Healthcare providers in the state of Western Australia.…”

“…34 Examples of specific applications are presented in Table 2. [27][28][29][30][31][32][33][34][35][36][37][38][39][40] Tools in pharmacovigilance and AEFI surveillance A variety of tools used to improve AEFI surveillance are used in these non-EU initiatives (Table 3). In Australia, the AusVaxSafety surveillance system that uses integrated software to identify and issue automated surveys via text messaging provides active near real-time surveillance capable of rapid data collection on a national level.…”

Early signal detection of adverse events following influenza vaccination using proportional reporting ratio, Victoria, Australia

“…A separate signal event occurred in 2015 when retrospective analyses of AEFI with seasonal influenza vaccines identified a probable increase in allergy-related AEFI [6]. In this instance, severity was fortunately insufficient to warrant modification of the program.…”