Establishing the Vaccine Safety Health Link: A large, linked data resource for the investigation of vaccine safety concerns.

Post-licensure vaccine safety surveillance of adverse events following immunisation is critical to ensure public safety and confidence in vaccines. This paper aims to describe the governance structure and data linkage methodology behind the establishment of the largest linked vaccine safety surveillance data resource in Australia - The Vaccine Safety Health Link (VSHL). The Vaccine Safety Health Link contains linked records from the Australian Immunisation Register with records from hospital, perinatal, mortality, and notifiable disease datasets in near real-time. Linkage is done by the Centre for Victorian Data Linkage who receive the datasets in an identifiable format which then undergo standardisation, enrichment, linkage, quality assurance and de-identification, prior to being supplied for analysis. The VSHL data resource allows sensitive and rapid analysis of a broad spectrum of suspected adverse events to ensure the safety of all vaccines administered. It is also used to refute spurious concerns where no associations are found, upholding trust, and maintaining vaccine confidence. The Vaccine Safety Health Link's surveillance design complements existing vaccine safety surveillance methods. Challenges encountered and lessons learnt using Vaccine Safety Health Link would benefit linkage projects globally. In its first two years, The Vaccine Safety Health Link has been used for 14 vaccine safety investigations. Studies into these conditions would not have otherwise been possible. The Vaccine Safety Health Link also partners with the Global Vaccine Data Network™ for approved collaborative studies with a combined population of over 300 million people.

Morgan HJ ，Clothier HJ ，Witowski P ，Boyd JH ，Kattan GS ，Dimaguila GL ，Shetty AN ，Buttery JP ... -  《-》

Continuous active surveillance of adverse events following immunisation using SMS technology.

On-going post-licensure surveillance of adverse events following immunisation (AEFI) is critical to detecting and responding to potentially serious adverse events in a timely manner. SmartVax is a vaccine safety monitoring tool that uses automated data extraction from existing practice management software and short message service (SMS) technology to follow-up vaccinees in real-time. We report on childhood vaccine safety surveillance using SmartVax at a medical practice in Perth, Western Australia. Parents of all children under age five years who were vaccinated according to the Australian National Immunisation Schedule between November 2011 and June 2015 were sent an SMS three days post administration to enquire whether the child had experienced a suspected vaccine reaction. Affirmative replies triggered a follow-up SMS requesting details of the reaction(s) via a link to a survey that could be completed using a smartphone or the web. Rates of reported AEFI including fever, headache, fatigue, rash, vomiting, diarrhoea, rigours, seizures, and local reactions were calculated by vaccination time point. Overall, 239 (8.2%; 95% CI 7.2-9.2%) possible vaccine reactions were reported for 2897 vaccination visits over the 44 month time period. The proportion of children experiencing a possible AEFI, mostly local reactions, was significantly greater following administration of diphtheria-tetanus-pertussis-poliomyelitis vaccine at 4 years of age (77/441; 17.5%; 95% CI 13.9-21.0%) compared to the vaccinations given at 2-18 months (p<0.001). Across all time points, local reactions and fatigue were the most frequently reported AEFI. Automated SMS-based reporting can facilitate sustainable, real-time, monitoring of adverse reactions and contribute to early identification of potential vaccine safety issues.

Westphal DW ，Williams SA ，Leeb A ，Effler PV ... -  《-》

Acute disseminated encephalomyelitis and transverse myelitis following COVID-19 vaccination - A self-controlled case series analysis.

Acute Disseminated Encephalomyelitis (ADEM) and Transverse Myelitis (TM) are within the group of immune mediated disorders of acquired demyelinating syndromes. Both have been described in temporal association following various vaccinations in case reports and case series and have been evaluated in observational studies. A recent analysis conducted by The Global Vaccine Data Network (GVDN) observed an excess of ADEM and TM cases following the adenoviral vectored ChAdOx1 nCoV-19 (AZD1222) and mRNA-1273 vaccines, compared with historically expected background rates from prior to the pandemic. Further epidemiologic studies were recommended to explore these potential associations. We utilized an Australian vaccine datalink, Vaccine Safety Health-Link (VSHL), to perform a self-controlled case series analysis for this purpose. VSHL was selected for this analysis as while VSHL data are utilised for GVDN association studies, they were not included in the GVDN observed expected analyses. The VSHL dataset contains vaccination records sourced from the Australian Immunisation Register, and hospital admission records from the Victorian Admitted Episodes Dataset for 6.7 million people. These datasets were used to determine the relative incidence (RI) of G040 (ADEM) and G373 (TM) ICD-10-AM coded admissions in the 42-day risk window following COVID-19 vaccinations as compared to control periods either side of the risk window. We observed associations between ChAdOx1 adenovirus vector COVID-19 vaccination and ADEM (all dose RI: 3.74 [95 %CI 1.02,13.70]) and TM (dose 1 RI: 2.49 [95 %CI: 1.07,5.79]) incident admissions. No associations were observed between mRNA COVID-19 vaccines and ADEM or TM. These findings translate to an extremely small absolute risk of ADEM (0.78 per million doses) and TM (1.82 per million doses) following vaccination; any potential risk of ADEM or TM should be weighed against the well-established protective benefits of vaccination against COVID-19 disease and its complications. This study demonstrates the value of the GVDN collaboration leveraging large population sizes to examine important vaccine safety questions regarding rare outcomes, as well as the value of linked population level datasets, such as VSHL, to rapidly explore associations that are identified.

Morgan HJ ，Clothier HJ ，Sepulveda Kattan G ，Boyd JH ，Buttery JP ... -  《-》

Evaluation of 'SAEFVIC', A Pharmacovigilance Surveillance Scheme for the Spontaneous Reporting of Adverse Events Following Immunisation in Victoria, Australia.

Clothier HJ ，Crawford NW ，Russell M ，Kelly H ，Buttery JP ... -  《-》

Process trumps potential public good: better vaccine safety through linked cross-jurisdictional immunisation data in Australia.

To provide insights into complexities of seeking access to state and federal cross-jurisdictional data for linkage with the Australian Childhood Immunisation Register (ACIR). We provide recommendations for improving access and receipt of linked datasets involving Australian Government-administered data. We describe requirements for linking eleven federal and state data sources to establish a national linked dataset for safety evaluation of vaccines. The required data linkage methodology for integrating cross-jurisdictional data sources is also described. Extensive negotiation was required with 18 different agencies for 21 separate authorisations and 12 ethics approvals. Three variations of the 'best practice' linkage model were implemented. Australian Government approval requests spanned nearly four years from initial request for data, with a further year before ACIR data transfer to the linkage agency. Integration of immunisation registers with other data collections is achievable in Australia but infeasible for routine and rapid identification of vaccine safety concerns. Lengthy authorisation requirements, convoluted disparate application processes and inconsistencies in data supplied all contribute to delayed data availability. Implications for public health: Delayed data access for safety surveillance prevents timely epidemiological reviews. Poor responsiveness to safety concerns may erode public confidence, compromising effectiveness of vaccination programs through reduced participation.

Duszynski KM ，Pratt NL ，Lynch JW ，Braunack-Mayer A ，Taylor LK ，Berry JG ，Xafis V ，Buttery J ，Gold MS ，Vaccine Assessment Using Linked Data (VALiD) Working Group ... -  《-》