Audiovestibular adverse events following COVID-19 vaccinations.

INTRODUCTION: Evidence regarding audiovestibular adverse events post COVID-19 vaccination to date has been inconclusive regarding a potential association. This study aimed to determine if there was an increase in audiovestibular events following COVID-19 vaccination in South-eastern Australia during January 2021-March 2023. METHODS: A multi-data source approach was applied. First, a retrospective observational analysis of spontaneous reports of audiovestibular events to a statewide vaccine safety surveillance service, SAEFVIC. Second, a self-controlled case series analysis using general practice data collected via the POpulation Level Analysis and Reporting (POLAR) tool. RESULTS AND CONCLUSIONS: This study is the first to demonstrate an increase in general practice presentations of vertigo following mRNA vaccines (RI = 1.40, P <.001), and tinnitus following both the Vaxzevria® adenovirus vector and mRNA vaccines (RI = 2.25, P <.001 and 1.53, P <.001 respectively). There was no increase in hearing loss following any COVID-19 vaccinations. Our study, however, was unable to account for the potential of concurrent COVID-19 infections, which literature has indicated to be associated with audiovestibular events. Healthcare providers and vaccinees should be alert to potential audiovestibular complaints after COVID-19 vaccination. Our analysis highlights the importance of using large real-world datasets to gather reliable evidence for public health decision making.

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.

Interdisciplinary Learning Health System Response to Public Vaccine Concerns.

In Victoria, Australia, jurisdictional vaccine safety service is conducted by SAEFVIC (Surveillance of Adverse Events Following Vaccination in the Community). SAEFVIC developed a public Vaccine Safety Report (saefvic.online/vaccinesafety) to present key surveillance information. This study applies an interdisciplinary learning health system approach to evaluate the report, taking into consideration public expressions of concern on social media.

What would have happened anyway? Population data source considerations when estimating background incident rates of adverse events following immunisation to inform vaccine safety.

INTRODUCTION: Understanding background incident rates of adverse events following immunisation (AEFI) is essential to rapidly detect, evaluate, respond to, and communicate about vaccine safety concerns, especially for new vaccines. Creating estimates based on geographic specific population level data is increasingly important, as new AEFI presentations will be subject to the same local influences of population demography, exposures, health system variations and level of health care sought. METHODS: We conducted a retrospective cohort analysis of hospital admissions, emergency department presentations and general practice consultations from 2015 to 2019-before introduction of COVID-19, Mpox or Shingrix vaccination-to estimate background incident rates for 37 conditions considered potential AEFI of special interest (AESI). Background incident rates per 100,000 population were calculated and presented as cases expected to occur coincidentally 1 day, 1 week and 6 weeks post-vaccination, by life-stage age-groups and presenting healthcare setting. We then assessed the proportional contribution of each data source to inform each AESI background rate estimate. RESULTS: 16,437,156 episodes of the 37 AESI were identified. Hospital admissions predominantly informed 19 (51%) of AESI, including exclusively ADEM and CVST; 8 AESI (22%) by primary care, and 10 (27%) a mix. Four AESI (allergic urticaria, Bell's palsy, erythema multiform and sudden death) were better informed by emergency presentations than admissions, but conversely 11 AESI (30%) were not captured in ICD-10 coded emergency presentations at all. CONCLUSIONS: Emergent safety concerns are inevitable in population-wide implementation of new vaccines, therefore understanding local background rates aids both safety signal detection as well as maintaining public confidence in vaccination. Hospital and primary care data sources can be interrogated to inform expected background incident rates of adverse events that may occur following vaccination. However, it is necessary to understand which data-source provides best intelligence according to nature of condition and presenting healthcare setting.

Shoulder injury following COVID-19 vaccine administration: a case series and proposed diagnostic algorithm.

BACKGROUND: Shoulder Injury Related to Vaccine Administration (SIRVA) is a preventable adverse event following incorrect vaccine administration, which can result in significant long-term morbidity. There has been a notable surge in reported cases of SIRVA as a rapid national population-based COVID-19 immunization program has been rolled out across Australia. METHODS: Surveillance of Adverse Events Following Vaccination in the Community (SAEFVIC) in Victoria identified 221 suspected cases of SIRVA following the commencement of the COVID-19 vaccination program, reported between February 2021 and February 2022. This review describes the clinical features and outcomes of SIRVA in this population. Additionally, a suggested diagnostic algorithm is proposed, in order to facilitate early recognition and management of SIRVA. RESULTS: 151 cases were confirmed as SIRVA, with 49.0% having received vaccines at state vaccination centers. 75.5% were suspected incorrect administration site, with most patients experiencing shoulder pain and restricted movement within 24 hours of vaccination, lasting on average 3 months. CONCLUSION: Improved awareness and education regarding SIRVA is imperative in a pandemic vaccine roll-out. The development of a structured framework for evaluating and managing suspected SIRVA will aid in timely diagnosis and treatment, essential to mitigate potential long-term complications.

Australasian Institute of Digital Health Summit 2022-Automated Social Media Surveillance for Detection of Vaccine Safety Signals: A Validation Study.

BACKGROUND: Social media platforms have emerged as a valuable data source for public health research and surveillance. Monitoring of social media and user-generated data on the Web enables timely and inexpensive collection of information, overcoming time lag and cost of traditional health reporting systems. OBJECTIVES: This article identifies personally experienced coronavirus disease 2019 (COVID-19) vaccine reactions expressed on Twitter and validate the findings against an established vaccine reactions reporting system. METHODS: We collected around 3 million tweets from 1.4 million users between February 1, 2021, to January 31, 2022, using COVID-19 vaccines and vaccine reactions keyword lists. We performed topic modeling on a sample of the data and applied a modified F1 scoring technique to identify a topic that best differentiated vaccine-related personal health mentions. We then manually annotated 4,000 of the records from this topic, which were used to train a transformer-based classifier to identify likely personally experienced vaccine reactions. Applying the trained classifier to the entire data set allowed us to select records we could use to quantify potential vaccine side effects. Adverse events following immunization (AEFI) referred to in these records were compared with those reported to the state of Victoria's spontaneous vaccine safety surveillance system, SAEFVIC (Surveillance of Adverse Events Following Vaccination In the Community). RESULTS: The most frequently mentioned potential vaccine reactions generally aligned with SAEFVIC data. Notable exceptions were increased Twitter reporting of bleeding-related AEFI and allergic reactions, and more frequent SAEFVIC reporting of cardiac AEFI. CONCLUSION: Social media conversations are a potentially valuable supplementary data source for detecting vaccine adverse event mentions. Monitoring of online observations about new vaccine-related personal health experiences has the capacity to provide early warnings about emerging vaccine safety issues.

Vaccine safety in Australia during the COVID-19 pandemic: Lessons learned on the frontline.

Surveillance of Adverse Events Following Vaccination in the Community (SAEFVIC), Victoria's vaccine safety service for reporting adverse events following immunisation (AEFI), has provided integrated spontaneous surveillance and clinical services for individuals affected by AEFI since 2007. We describe SAEFVIC's response to the COVID-19 vaccine program, and reflect on lessons learned for vaccine safety. The massive scale of the Australian COVID-19 vaccine program required rapid adaptations across all aspects of SAEFVIC's vaccine safety services. Collection of AEFI reports was streamlined and expanded, incorporating both spontaneous and active surveillance data. Dramatically increased report volumes were managed with additional staffing, and innovations to automate, filter, and triage reports for priority follow up. There were two major adverse events of special interest (AESI): thrombosis with thrombocytopaenia syndrome and myocarditis, with multiple other AESI also investigated. Rapid escalation mechanisms to respond to AESI were established, along with AESI-specific databases for enhanced monitoring. Vaccine education and training resources were developed and public-facing vaccine safety reports updated weekly. Frequent communication with local and national government and regulatory bodies, and consultation with specialist groups was essential. The COVID-19 vaccine program has highlighted the importance of vaccine safety in supporting public confidence in vaccines and informing evidence-based immunisation policy. Supporting the COVID-19 vaccine program has required flexibility in adapting to policy changes and evolving vaccine safety signals, careful triage and prioritisation, informatics innovation, and enhanced engagement with the public regarding vaccine safety. Long-term investment to continue strengthening vaccine safety systems, building on lessons learned, will be essential for the ongoing success of Australian vaccination programs.

Guillain-Barré syndrome temporally associated with COVID-19 vaccines in Victoria, Australia.

Guillain-Barré syndrome (GBS) is an adverse event of special interest (AESI) for surveillance systems monitoring adverse events following immunisation (AEFI) with COVID-19 vaccines. Emerging data support a temporal association between GBS and adenovirus-vector COVID-19 vaccines. We present a case series of GBS reports submitted between February and November 2021 to our enhanced spontaneous surveillance system (SAEFVIC) in Victoria, Australia, following vaccination with either the adenovirus-vector vaccine Vaxzevria ChadOx1-S (AstraZeneca) or an mRNA vaccine (Comirnaty BNT162b2 [Pfizer-BioNTech] or Spikevax mRNA-1273 [Moderna]). For each report, Brighton Collaboration case definitions were used to describe diagnostic certainty. Severity was graded using the GBS Disability Score. The observed incidence of GBS following immunisation against COVID-19 was compared to expected background ICD10-AM G61.0 coded hospitalisations. There were 41 total cases of GBS reported to SAEFVIC following Vaxzevria (n = 38), Comirnaty (n = 3), or Spikevax (n = 0) vaccines. The observed GBS incidence rate exceeded the expected background rate for Vaxzevria only, with 1.85 reports per 100,000 doses following dose 1, higher than the expected rate of 0.39 hospital admissions per 100,000 adults within 42 days of vaccination. Of 38 GBS reports following Vaxzevria, the median age at vaccination was 66 years and median onset of symptoms was 14 days following immunisation. There was one death. Four cases initially categorised as GBS were later reclassified as acute-onset chronic inflammatory demyelinating polyneuropathy. Fatigue was the predominant persisting symptom reported at follow up. Additional global studies are required to characterise risk factors, clinical variability, and to provide precision and generalizability regarding AEFI risks such as GBS associated with different vaccine platforms, which will help inform communication of the potential benefits and risks of COVID19 vaccination.

Myocarditis and myopericarditis cases following COVID-19 mRNA vaccines administered to 12-17-year olds in Victoria, Australia.

IMPORTANCE: COVID-19 mRNA vaccine-associated myocarditis has previously been described; however specific features in the adolescent population are currently not well understood. OBJECTIVE: To describe myocarditis adverse events following immunisation reported following any COVID-19 mRNA vaccines in the adolescent population in Victoria, Australia. DESIGN: Statewide, population-based study. SETTING: Surveillance of Adverse Events Following Vaccination in the Community (SAEFVIC) is the vaccine-safety service for Victoria, Australia. PARTICIPANTS: All SAEFVIC reports of myocarditis and myopericarditis in 12-17-year-old COVID-19 mRNA vaccinees submitted between 22 February 2021 and 22 February 2022, as well as accompanying diagnostic investigation results where available, were assessed using Brighton Collaboration criteria for diagnostic certainty. EXPOSURES: Any mRNA COVID-19 vaccine. MAIN OUTCOMES/MMEASURE: Confirmed myocarditis as per Brighton Collaboration criteria (levels 1-3). RESULTS: Clinical review demonstrated definitive (Brighton level 1) or probable (level 2) diagnoses in 75 cases. Confirmed myocarditis reporting rates were 8.3 per 100 000 doses in this age group. Cases were predominantly male (n=62, 82.7%) and post dose 2 (n=61, 81.3%). Rates peaked in the 16-17-year-old age group and were higher in males than females (17.7 vs 3.9 per 100 000, p=<0.001).The most common presenting symptoms were chest pain, dyspnoea and palpitations. A large majority of cases who had a cardiac MRI had abnormalities (n=33, 91.7%). Females were more likely to have ongoing clinical symptoms at 1-month follow-up (p=0.02). CONCLUSION: Accurate evaluation and confirmation of episodes of COVID-19 mRNA vaccine-associated myocarditis enabled understanding of clinical phenotypes in the adolescent age group. Any potential vaccination and safety surveillance policies needs to consider age and gender differences.

Victorian Specialist Immunisation Services (VicSIS) - bolstering adult clinics for COVID-19 vaccines.

The Victorian Specialist Immunization Services (VicSIS) was established in Victoria, Australia, in February 2021, aiming to enhance vaccine safety services for Coronavirus disease (COVID-19) vaccines. VicSIS supports practitioners and patients with complex vaccine safety questions, including those who experience adverse events following immunization (AEFI) after COVID-19 vaccines. VicSIS provides individual vaccination recommendations, allergy testing, vaccine challenges, and vaccination under supervision. VicSIS initially comprised of eight adult COVID-19 specialist vaccination clinics, subsequently, expanding to better support pediatric patients as the Australian vaccine roll-out extended to adolescents and children. Since their establishment to September 2021, the inaugural VicSIS clinics received a total of 26,401 referrals and reviewed 6,079 patients. Consults were initially predominantly for pre-vaccination reviews, later predominantly becoming post-vaccination AEFI reviews as the program progressed. Regardless of the type of consult, the most common consult outcome was a recommendation for routine vaccination (73% and 55% of consult outcomes respectively). VicSIS is an integral component of the COVID-19 vaccination program and supports confidence in COVID-19 vaccine safety by providing consistent advice across the state. VicSIS aims to strengthen the health system through the pandemic, bolstering specialist immunization services beyond COVID-19 vaccines, including training the next generation of vaccinology experts.

Immune thrombocytopenia following immunisation with Vaxzevria ChadOx1-S (AstraZeneca) vaccine, Victoria, Australia.

Emerging evidence suggest a possible association between immune thrombocytopenia (ITP) and some formulations of COVID-19 vaccine. We conducted a retrospective case series of ITP following vaccination with Vaxzevria ChadOx1-S (AstraZeneca) and mRNA Comirnaty BNT162b2 COVID-19 (Pfizer-BioNTech) vaccines and compare the incidence to expected background rates for Victoria during the first six months of the Australian COVID-19 vaccination roll-out in 2021. Cases were identified by reports to the Victorian state vaccine safety service, SAEFVIC, of individuals aged 18 years or older presenting with thrombocytopenia following COVID-19 vaccination without evidence of thrombosis. Twenty-one confirmed or probable cases of ITP were identified following receipt of AstraZeneca (n = 17) or Pfizer-BioNTech (n = 4) vaccines. This translates to an observed incidence of 8 per million doses for AstraZeneca vaccine, twice the expected background rate of 4.1 per million. The observed rate for Pfizer-BioNTech was consistent with the expected background rate. The median time to onset for the cases post AstraZeneca vaccination was 10 days (range 1-78) and median platelet nadir 5 × 109/L (range 0-67 × 109/L). Hospital presentations or admissions for management of symptoms such as bleeding occurred in 18 (86%) of the cases. The majority of cases (n = 11) required intervention with at least 2 therapy modalities. In conclusion, we observed a substantially higher than expected rate of ITP following AstraZeneca vaccination. ITP is the second haematological adverse event, distinct from that of thrombosis with thrombocytopenia syndrome (TTS), observed following AstraZeneca vaccination.

SAEFVIC: Surveillance of adverse events following immunisation (AEFI) in Victoria, Australia, 2018.

BACKGROUND: SAEFVIC is the Victorian surveillance system for adverse events following immunisation (AEFI). It enhances passive surveillance by also providing clinical support and education to vaccinees and immunisation providers. This report summarises surveillance, clinical and vaccine pharmacovigilance activities of SAEFVIC in 2018. METHODS: A retrospective observational cohort study of AEFI reports received by SAEFVIC in 2018, compared with previous years since 2008. Data were categorised by vaccinee demographics of age, sex, pregnancy and Indigenous status, vaccines administered and AEFI reactions reported. Age cohorts were defined as infant (0-12 months); young child (1-4 years); school-aged (5-17 years); adult (18-64 years); and older person (65+ years). Proportional reporting ratios were calculated for signal investigation of serious adverse neurological events with all vaccines and with influenza vaccines. Clinical support services and educational activities are described. RESULTS: SAEFVIC received 1730 AEFI reports (26.8 per 100,000 population), with 9.3% considered serious. Nineteen percent (n = 329) attended clinical review. Annual AEFI reporting trends increased for infants, children and older persons, but were stable for school-aged and adult cohorts. Females comprised 55% of all reports and over 80% of reports among adults. There were 17 reports of AEFI in pregnant women and 12 (0.7%) in persons identifying as Indigenous Australians. A possible signal regarding serious adverse neurological events (SANE) was detected, but was not supported by signal validation testing. A clinical investigation is ongoing. Two deaths were reported coincident to immunisation with no evidence of causal association. CONCLUSION: SAEFVIC continues to provide robust AEFI surveillance supporting vaccine safety monitoring in Victoria and Australia, with new signal detection and validation methodologies strengthening capabilities.

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

INTRODUCTION: Timely adverse event following immunisation (AEFI) signal event detection is essential to minimise further vaccinees receiving unsafe vaccines. We explored the proportional reporting ratio (PRR) ability to detect two known signal events with influenza vaccines with the aim of providing a model for prospective routine signal detection and improving vaccine safety surveillance in Australia. METHODS: Passive AEFI surveillance reports from 2008-2017 relating to influenza vaccines were accessed from the Australian SAEFVIC (Victoria) database. Proportional reporting ratios were calculated for two vaccine-event categories; fever and allergic AEFI. Signal detection sensitivity for two known signal events were determined using weekly data; cumulative data by individual year and; cumulative for all previous years. Signal event thresholds of PRR ≥2 and Chi-square ≥4 were applied. RESULTS: PRR provided sensitive signal detection when calculated cumulatively by individual year or by all previous years. Known signal events were detected 15 and 11 days earlier than traditional methods used at the time of the actual events. CONCLUSION: Utilising a single jurisdiction's data, PRR improved vaccine pharmacovigilance and showed the potential to detect important safety signals much earlier than previously. It has potential to maximise immunisation safety in Australia. This study progresses the necessary work to establish national cohesion for passive surveillance signal detection and strengthen routine Australian vaccine pharmacovigilance.

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

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.

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

INTRODUCTION: Australia is traditionally an early adopter of vaccines, therefore comprehensive and effective post-licensure vaccine pharmacovigilance is critical to maintain confidence in immunisation, both nationally and internationally. With adverse event following immunisation (AEFI) surveillance the responsibility of Australian jurisdictions, Victoria operates an enhanced passive AEFI surveillance system integrated with clinical services, called 'SAEFVIC' (Surveillance of Adverse Events Following Vaccination In the Community). OBJECTIVE: The aim of this study was to evaluate Victoria's current AEFI surveillance system 'SAEFVIC' and inform ongoing quality improvement of vaccine pharmacovigilance in Victoria and Australia. METHODS: We conducted a retrospective structured desktop evaluation of AEFI reporting received by SAEFVIC from 2007 to 2014, to evaluate the system according to its stated objectives, i.e. to improve AEFI reporting; provide AEFI signal detection; and to maintain consumer confidence in vaccination. RESULTS: AEFI reporting has tripled since SAEFVIC commenced (incidence risk ratio [IRR] 3.04, 95% confidence interval [CI] 2.35-3.93), raising Victoria to be the lead jurisdiction by AEFI reporting volume and to rank third by population reporting rate nationally. The largest increase was observed in children. Data were utilised to investigate potential signal events and inform vaccine policy. Signal detection required clinical suspicion by surveillance nurses, or prior vaccine-specific concerns. Subsequent vaccination post-AEFI was documented for 56.2% (95% CI 54.1-58.4) of reports, and the proportion of children due or overdue for vaccination was 2.3% higher for those reporting AEFI compared with the general population. CONCLUSION: SAEFVIC has improved AEFI surveillance, facilitates signal investigation and validation, and supports consumer confidence in immunisation. Expansion of the system nationally has the potential to improve capacity and capability of vaccine pharmacovigilance, particularly through data consistency and jurisdictional comparability in Australia.

Limited provision of diagnostic services to Victorians living with hepatitis C antibodies, 2001-2012: a multi-level modelling analysis.

OBJECTIVE: To determine what percentage of Victorians with a history of notified hepatitis C exposure received appropriate follow-up diagnostic services between 2001 and 2012. METHODS: Individual notification data and aggregate Medicare and supplementary testing data were entered into a compartmental transition model, which was used to estimate the percentage of people with a hepatitis C notification who were yet to receive either a negative diagnostic test for viral nucleic acid, or a test for viral genotype, at the end of 2012. RESULTS: We estimate that 58.2% (uncertainty interval: 42.2%, 72.4%) of Victorians with a hepatitis C notification between 2001 and 2012 did not receive either a negative test for viral nucleic acid or a viral genotyping test during the study period. At the end of 2012, we estimate there were approximately 20,400 Victorians living with hepatitis C antibodies who were yet to receive testing, of which approximately 9,300 would have been aged 45 years or older. CONCLUSIONS: A majority of people living with HCV antibodies in Victoria had not received appropriate secondary diagnostic services as of the end of 2012. IMPLICATIONS: As improved therapeutic options become available for people living with chronic hepatitis C, measures to support appropriate follow-up of people with suspected or confirmed chronic infections via primary care services will be required.

Bacillus Calmette-Guérin (BCG) vaccine adverse events in Victoria, Australia: analysis of reports to an enhanced passive surveillance system.

BACKGROUND: Bacillus Calmette-Guérin (BCG) vaccine is used worldwide, with high efficacy against childhood Mycobacterium tuberculosis (TB) meningitis and miliary TB. BCG vaccine is considered safe, with serious systematic adverse events following immunization (AEFI) of immunocompetent recipients being rare, although adverse event rates vary between differing BCG strains. In Victoria, Australia, AEFI are reported to SAEFVIC (Surveillance of Adverse Events Following Vaccination In the Community), an enhanced passive surveillance system operational since 2007. OBJECTIVE: To describe the epidemiology of reported BCG AEFI in Victoria, Australia, particularly following the 2012 recall of Connaught BCG vaccine, substitution with Denmark-SSI vaccine and subsequent programme delivery adjustments. METHODS: Retrospective analysis of reported BCG AEFI in Victoria, Australia, for the 6-year period 2008-2013. Incidence rates were calculated using available doses-distributed, doses-administered and population data denominators with 95 % confidence intervals. RESULTS: The predominant BCG AEFI reported were abscess and lymphadenopathy, with higher reports for males than for females (p = 0.039).The rates of AEFI per 10,000 doses distributed were similar for the Connaught and Denmark-SSI strains, at 11.6 and 15.4, respectively (p = 0.414). When doses administered rather than doses distributed were considered, the rate of reported Denmark-SSI AEFI was much higher, at 62.8 per 10,000 doses administered. Meaningful result interpretation was hampered by a lack of a BCG vaccination register, multiple disparate providers and absent doses-administered data prior to the recall. CONCLUSION: Effective AEFI surveillance is of paramount importance as countries are faced with unplanned vaccine strain changes following the 2012 BCG recall and subsequent global vaccine supply shortages. The Australian experience and lessons learned serve as a timely reminder to BCG vaccination programmes worldwide to review AEFI surveillance systems.