National pharmacovigilance of seasonal influenza vaccines in Australia

• DOI: 10.5694/mja2.52381
• Publication Date: 2024-07-15T08:15:35Z
• Authors: Megan O'Moore; Belinda Jones; Megan Hickie; Catherine Glover; Lucy Deng; Yuanfei Huang; Michael Dymock; Evelyn Tay; Julie A Marsh; Nicholas Wood
• Keywords: Seasonal influenza

The early detection of adverse events following immunisation (AEFI) is essential to protect public health and maintain confidence in vaccination. Vaccine pharmacovigilance — the monitoring, detection, investigation actioning vaccine safety signals occurs across a collaborative landscape that includes Therapeutic Goods Administration (TGA), nationally funded surveillance initiative AusVaxSafety, state territory departments. purpose these systems monitor for unexpected types rates AEFI, including rare population-specific events.1, 2 identification potential concerns key function systems, with TGA also focused on ensuring vaccines registered use Australia favourable benefit–risk profile. post-market monitoring supports Australia's seasonal influenza vaccination program. Annual recommended all individuals over six months age fully at-risk groups through National Immunisation Program.3 widespread distribution vaccines, particularly children Program, annual formulation changes cover new virus strains mean need be sensitive responsive. In 2023, about 9 million were administered Australians.4 This was substantially fewer than 11 2022, notably lower coverage Aboriginal Torres Strait Islander peoples.5, 6 Although there are varied complex reasons affect uptake, this article aims support program by providing robust national processes Australia. All AEFI reported used TGA's contribute vaccine's reports submitted entered into internal database Australian Adverse Event Management System (AEMS). receives spontaneous (passive) medicines care professionals, pharmaceutical companies (Australian sponsors), departments, public. sponsors required under legislation report serious reactions TGA.7 most states territories, providers have statutory obligation certain reporting channels. These included AEMS. shares information accordance cooperative data-sharing arrangements. territories contributors collection accounting majority AEMS dataset 2023. event must include details suspected product involved, patient such as or date birth, well reporter. may seek additional follow-up cases insufficient details, which typically facilitated relevant After report, coded using standardised Medical Dictionary Regulatory Activities (MedDRA). Information from made publicly available Database Notifications. Some not if found duplicate valid; example, occurred before administered. assessment an determined either reporter during review. identifies reviews regulatory significance, concern, consider convening Safety Investigation Group when concern identified has change balance vaccine, safety. independent expert panel undertake causality assessments assist individual concern. outcomes serve inform action addition case review, data mining algorithms. recognised method signal based concept disproportionality provides measure whether associated drug (termed drug-adverse pair) more frequently compared other pairs background dataset.9, 10 uses data-mining algorithms interrogate identify vaccine-adverse greater number expected. Disproportionality analyses performed monthly antigens trade names (brands). activities informed local external AEMS, international data. investigate interagency communication (including notification AusVaxSafety), meetings authorities (TGA AEFI–Jurisdictional Coordinator meetings), regulators, companies, published literature2 (Box). investigations reports, observed versus expected numbers (using dose derived Register), global findings World Health Organization Vigibase (a reports), literature, specificity biological plausibility event. Advice requested Advisory Committee Vaccines any taken reduce risk Seasonal monitored completed throughout season. review documentation give detailed special interest pyrexia, febrile convulsion, seizure, Guillain–Barré syndrome. brands analysed, consideration given (weekly, cumulative), rates, proportional ratio trend analyses. Observed syndrome conducted. updates shared Centre Research Surveillance, AusVaxSafety regular AEFI– Jurisdictional meetings. Technical provided routine broader context Program. New Register added respiratory syncytial Arexvy (GSK) ABRYSVO (Pfizer) Shingrix (GSK), closely similar enhanced processes. active brand- age-specific annually since 2014.11 As part surveillance, surveys sent via SMS email recipients vaccinated at representative sample sentinel sites general practices, pharmacies, Community Controlled Organisations, centres. Surveys three days after they received vaccine. then fast initial response cumulative summation (FIR CUSUM) weekly basis both fever (among aged five years) medical attendance presentation practice, worker, and/or emergency department). FIR CUSUM tracks relative likelihood underlying rate (fever attendance) maximum acceptable it rate, accumulated pre-specified values parameters, threshold.12 results Government Department Aged Care, TGA, jurisdictions. Summaries website.13 order align methodologically coronavirus disease 2019 (COVID-19) commenced March 2021, updated 2022.14 survey regard questions asked (to match solicited COVID-19 vaccination) delivery (one link sent, contrast former multistage process). update enables informative concomitant addition, Bayesian posterior predictive analysis 2022. estimates predicted future conditional each week. adjusts age, sex, jurisdiction, Indigenous status chronic condition within population responding survey. A flagged actual exceeds 99th percentile distribution. two methods differ their sensitivity longer term departures fixed baseline shorter acute (posterior analysis). such, statistical complementary allow comparison between detected. diverse range considered remain challenges investigation. system affected inherent limitations under-reporting incomplete reports. Under-reporting limitation individual's knowledge access pathways, perceived importance reporting.15, 16 noted 2013 article,15 important factors time uncertain causality, single non-serious Accurate timely rapid dependent upon action.17 Therefore, encourages patients clinicians committed enhancing facilitate easy access. concurrent work synergy help mitigate prompting who AEFI. However, quality self-reports presence missing impact For passive departments attainment cases. Reporters encouraged provide much possible event, further sought. long late-onset another challenge captured day 3 surveys. Their requires alert involvement conditions, TGA. Despite limitations, demonstrated ability rapidly detect enabled prompt vaccines. Ongoing improvements underway enhance capture ensure continued market, Current being explored completeness ethnicity reporting, methodologies. Updates aim increase functionality system, opportunities streamlined exchange. actively involved planned enhancements interoperability work. Education modules developed practitioner awareness engagement reporting. recognise transparent Close collaboration continues Australians close emerging signals. contract Care. authors acknowledge participants staff sites, Telethon Kids Institute, contribution tools SmartVax, Vaxtracker, Microsoft COVID System. wish thank Surveillance Section, Medicine Defects Improvement No disclosures. Not commissioned; externally peer reviewed. ACV = Vaccines; Events System; ATAGI Immunisation; DAEN Notifications; NCIRS Surveillance; PI information; Administration; UMC Uppsala Monitoring Centre; WHO Organization.