A pilot project harnessing surveillance systems to support clinicians providing clinical care for people diagnosed with hepatitis C in Victoria, Australia, September 2021 to 31 March 2022.

BackgroundActive follow-up of chronic hepatitis C notifications to promote linkage to care is a promising strategy to support elimination.AimThis pilot study in Victoria, Australia, explored if the Department of Health could follow-up on hepatitis C cases through their diagnosing clinicians, to assess and support linkage to care and complete data missing from the notification.MethodsFor notifications received between 1 September 2021 and 31 March 2022 of unspecified hepatitis C cases (i.e. acquired > 24 months ago or of unknown duration), contact with diagnosing clinicians was attempted. Data were collected on risk exposures, clinical and demographic characteristics and follow-up care (i.e. HCV RNA test; referral or ascertainment of previous negative testing or treatment history). Reasons for unsuccessful doctor contact and gaps in care provision were investigated. Advice to clinicians on care and resources for clinical support were given on demand.ResultsOf 513 cases where information was sought, this was able to be obtained for 356 (69.4%). Reasons for unsuccessful contact included incomplete contact details or difficulties getting in touch across three attempts, particularly for hospital diagnoses. Among the 356 cases, 307 (86.2%) had received follow-up care. Patient-management resources were requested by 100 of 286 contacted diagnosing clinicians.ConclusionsMost doctors successfully contacted had provided follow-up care. Missing contact information and the time taken to reach clinicians significantly impeded the feasibility of the intervention. Enhancing system automation, such as integration of laboratory results, could improve completeness of notifications and support further linkage to care where needed.

Evaluating a novel model of hepatitis B care, Hep B PAST, in the Northern Territory of Australia: results from a prospective, population-based study.

Background: The Northern Territory (NT) has the highest prevalence of chronic hepatitis B (CHB) in Australia. The Hep B PAST program aims to improve health outcomes for people living with CHB. Methods: This mixed methods study involves First Nations peoples living in the NT. We used participatory action research principles across three steps: 1. Foundation step: establishing hepatitis B virus (HBV) status and linkage to care; 2. Capacity building: training the health workforce; 3. Supported transition to primary healthcare: implementation of the "Hub and Spoke" model and in-language resources. Analysis occurred at three time points: 1. Pre-Hep B PAST (2018); 2. Foundation step (2020); and 3. Completion of Hep B PAST (2023). Evaluation focuses on four key indicators, the number of people: 1) with documented HBV status; 2) diagnosed with CHB; 3) receiving care; and 4) receiving treatment. Findings: Hep B PAST (2018-23) reached 40,555 people. HBV status was documented in 11% (1192/10,853), 79.2% (26,075/32,915) and 90.8% (28,675/31,588) of people at pre-Hep B PAST, foundation step, and completion respectively. An estimated 99.9% (821/822) of people were diagnosed, 86.3% (709/822) engaged in care, and 24.1% (198/822) on antiviral treatment at completion. CHB prevalence in the study population is 2.6%, decreasing from 6.1% to 0.4% in the pre- and post-vaccination cohorts. Interpretation: Hep B PAST is an effective model of care. Partner health services are exceeding elimination targets. This model could enable other countries to enhance the cascade of care and work towards eliminating HBV. Funding: National Health and Medical Research Council.

Community health workers' dissemination of COVID-19 information and services in the early pandemic response: a systematic review.

BACKGROUND: Community health workers (CHWs) had important roles mitigating the impact of the COVID-19 pandemic in vulnerable communities. We described how CHWs supported the dissemination of COVID-19 information and services during the early pandemic response. METHODS: Online article searches were conducted across five scientific databases, with review article reference lists hand searched to identify grey/unpublished literature. Articles were included if they reported on a program that engaged CHWs and aimed to prevent/control COVID-19. RESULTS: Nineteen relevant programs were identified from 18 included articles. CHWs were widely engaged in the pandemic response, especially in low- and middle-income countries and in vulnerable communities. CHWs' ability to effectively disseminate COVID-19 information/services was enabled by community trust and understanding community needs. CHWs were often underfunded and required to work in difficult conditions. Pre-existing services incorporating CHWs rapidly adapted to the new challenges brought by the pandemic. CONCLUSIONS: We recommend establishing programs that employ CHWs to disseminate health information and services in communities at-risk of misinformation and poor health outcomes during non-pandemic times. CHWs are well-placed to deliver interventions should an infectious disease outbreak arise. Having pre-existing trusted relationships between CHWs and community members may help protect vulnerable groups, including when outbreaks occur.

Evaluating a peer-to-peer health education program in Australian public housing communities during the COVID-19 pandemic.

BACKGROUND: The cohealth Health Concierge program operated in Melbourne, Australia from July 2020 to 30 June 2022. It provided peer-to-peer support to culturally and linguistically diverse residents of high-rise public housing. During this time, the COVID-19 public health response changed frequently and included movement restriction, testing and vaccination. We conducted a mixed-methods evaluation to determine the Health Concierge program's impact on residents' engagement with health services and public health activities. METHODS: The evaluation, informed by a Project Reference Group, used the RE-AIM framework. We analysed data from 20,901 routinely collected forms describing interactions between Concierges and residents from August 2021 to May 2022. Additional evaluation-specific data were collected between March and May 2022 in four housing estates; we surveyed 301 residents and conducted 32 interviews with residents, Concierges and program stakeholders. RESULTS: Concierges promoted COVID-safe behaviours; linked residents with support, testing and vaccination services; and disseminated up-to-date information. Of the 20,901 recorded interactions, 8,872 (42%) included Concierges providing support around COVID-19 vaccination. Most surveyed residents (191/301, 63%) reported speaking with a Concierge in the previous six months. The self-reported two-dose COVID-19 vaccine uptake was 94% (283/301). Some residents described having meaningful, appreciated conversations with Concierges, and some described superficial interactions. While residents initially welcomed the program, many felt it failed to evolve. Poorly defined management and hiring criteria led to variable program implementation. A need for bicultural workers to continue linking residents with services was discussed. CONCLUSIONS: Concierges' impact on residents may have contributed to high community uptake of COVID-19 testing and vaccination, and had benefits beyond the COVID-19 remit. We recommend the program be revised and continued to inform further preparedness planning and support service access generally. Program models such as this have potential to inform and reassure high-risk communities during a pandemic. In addition, such programs can help overcome vaccine hesitancy and promote protective health behaviours, regardless of whether a pandemic is currently occurring. Ensuring these programs remain responsive to the changing needs of end-users needs over time is imperative.

Progress towards triple elimination of mother-to-child transmission of HIV, hepatitis B and syphilis in Pacific Island Countries and Territories: a systematic review.

The diverse geographic, demographic, and societal factors in the Pacific Island Countries and Territories (PICTs) have contributed to unique epidemiological patterns of HIV, syphilis, and hepatitis B. Transmission can be during pregnancy, at the time of birth or via breastfeeding for HIV, and can have long-term adverse outcomes. Given the similarities in prevention of mother-to-child transmission of these infections, coordinated interventions for triple elimination are used. This systematic review has evaluated the peer-reviewed literature, grey literature, and global databases to assess the availability of data to report against elimination targets in the WHO Regional Framework for the Triple Elimination of Mother-to-Child Transmission of HIV, Hepatitis B and Syphilis in Asia and the Pacific 2018-2030. The secondary objective is to report on progress towards these targets. The findings show that none of the PICTs are on track to achieve triple elimination by 2030. Amongst the limited publicly available indicator data, there is suboptimal coverage for most indicators. It is important that there is an increase in availability of and access to antenatal care, testing, and treatment for pregnant women. Increased efforts are needed to collect data on key indicators and integrate reporting into existing systems to avoid extra burden. Funding: Leila Bell was supported by an Australian Government Research Training Program (RTP) Scholarship, Australia. Funding sources had no role in paper design, data collection, data analysis, interpretation, or writing of the paper.

Hepatitis C direct-acting antiviral treatment completion: Comparison of geographic, demographic and clinical characteristics in Australia.

BACKGROUND AND OBJECTIVES: Hepatitis C virus treatment uptake varies by geographic area in Australia; however, analysis has not been conducted on variations in treatment completion. This study investigated treatment completion according to remoteness, as well as demographic and clinical characteristics. METHOD: A retrospective analysis was conducted on all Pharmaceutical Benefits Scheme claim data from March 2016 to June 2019. Treatment was considered completed if all prescriptions required to complete the course were dispensed. Treatment completion was compared by remoteness of residence, sex, age, state or territory, treatment duration and prescriber type. RESULTS: Of 68,940 patients, 85.6% completed treatment, although the completion rate decreased over time. Residents living in very remote areas had the lowest treatment completion rate (74.3%; odds ratio [OR] 0.52; 95% confidence interval [CI]: 0.39, 0.7; P < 0.005), particularly those treated by general practitioners (GPs; 66.7%; OR 0.47; 95% CI: 0.22, 0.97; P = 0.042). DISCUSSION: This analysis suggests that people in very remote areas of Australia have the lowest hepatitis C treatment completion rate, particularly those accessing treatment through GPs. Further investigation into predictors of low treatment completion within these populations is required.

Missed opportunities for diagnosis of hepatitis B and C in individuals diagnosed with decompensated cirrhosis or hepatocellular carcinoma.

BACKGROUND AND AIM: This study aimed to assess utilization of health-care services in people with decompensated cirrhosis (DC) or hepatocellular carcinoma (HCC) and a "late diagnosis" of hepatitis B or hepatitis C. METHODS: Hepatitis B and C cases during 1997-2016 in Victoria, Australia, were linked with hospitalizations, deaths, liver cancer diagnoses, and medical services. A late diagnosis was defined as hepatitis B or hepatitis C notification occurring after, at the same time, or within 2 years preceding an HCC/DC diagnosis. Services provided during the 10-year period before HCC/DC diagnosis were assessed, including general practitioner (GP) or specialist visits, emergency department presentations, hospital admissions, and blood tests. RESULTS: Of the 25 766 notified cases of hepatitis B, 751 (2.9%) were diagnosed with HCC/DC, and hepatitis B was diagnosed late in 385 (51.3%). Of 44 317 cases of hepatitis C, 2576 (5.8%) were diagnosed with HCC/DC, and hepatitis C was diagnosed late in 857 (33.3%). Although late diagnosis dropped over time, missed opportunities for timely diagnosis were observed. Most people diagnosed late had visited a GP (97.4% for hepatitis B, 98.9% for hepatitis C) or had a blood test (90.9% for hepatitis B, 88.6% for hepatitis C) during the 10 years before HCC/DC diagnosis. The median number of GP visits was 24 and 32, and blood tests 7 and 8, for hepatitis B and C, respectively. CONCLUSIONS: Late diagnosis of viral hepatitis remains a concern, with the majority having frequent health-care service provision in the preceding period, indicating missed opportunities for diagnosis.

Mapping the delivery of interventions for vaccine-preventable infections in pregnancy in Victoria, Australia.

BACKGROUND: Standard care for pregnant women includes universal screening for hepatitis B, and administration of influenza and pertussis vaccination to women and hepatitis B infant vaccination. This study explored how perinatal services relating to the prevention of these vaccine-preventable diseases are delivered to women and their infants in Victoria, Australia. METHODS: Two online surveys investigated service delivery for the prevention of influenza, pertussis and hepatitis B to identify barriers to optimal care during January-June 2021; (1) The Birthing Hospitals Survey captured facility-level information about service delivery for influenza and pertussis vaccination, and interventions to prevent mother-to-child-transmission of chronic hepatitis B (CHB); and (2) The Healthcare Providers Survey captured individual staff perceptions and knowledge in community and hospital settings. RESULTS: Thirty-four hospital unit managers (61%) completed The Birthing Hospitals Survey . One-hundred and forty participants completed The Healthcare Providers Survey . Half of the birthing hospitals provided influenza (50%) and pertussis (53%) vaccinations to pregnant women, and 53% provided an infectious diseases service for women with CHB. Barriers to optimal care delivery included reliance on pregnant woman's self-report to confirm influenza, pertussis vaccination and CHB status, lack of standardised reporting, inadequate workforce training, poor communication between services, and lack of guideline-based clinical care for mothers with CHB and their infants. Three hospitals reported 'stock out' of hepatitis B immunoglobulin (HBIG). CONCLUSION: Coordinated and standardised system and clinical care improvements are required to provide equitable care for pregnant women and their infants, including training and education for healthcare providers, improving data capture and communication among health services.

Uptake of perinatal immunoprophylaxis for infants born to women with a record of hepatitis B in Victoria (2009-2017).

BACKGROUND: Mother-to-child transmission (MTCT) of hepatitis B virus (HBV) remains one of the leading causes of transmission worldwide. An estimated 90 % of infants who are exposed to HBV and do not receive appropriate post exposure immunoprophylaxis will go on to develop chronic hepatitis B (CHB). In Australia, universal birth dose vaccination was adopted in 2000 and universal antenatal screening for hepatitis B was introduced in the 1990 s, however up to 10 % of women may have missed screening. There is no coordinated care or data collection that systematically reports the access to interventions to prevent mother-to-child transmission (PMTCT) for women with CHB. Therefore, the incidence rate of MTCT is unknown. METHODS: We conducted retrospective data linkage of perinatal records, public health notification and hospital admission data to identify women with a record of HBV infection who had given birth to a live infant(s) in Victoria between 2009 and 2017. We assessed uptake of birth dose vaccination and hepatitis B immunoglobulin (HBIG) and explored factors associated with administration of birth dose recorded as administered within 7 days. RESULTS: Among 690,052 live births, 6118 births (0.90 %) were linked to 4196 women with a record of HBV infection. 89.4 % of all Victorian infants (n = 616,879), and 96.8 % of infants linked to women with a positive record of CHB (n = 5,925) received birth dose within 7 days. Infants born in private hospitals had reduced odds of receiving birth dose when compared to public hospitals births (Victorian population, aOR = 0.67, 95 %CI = 0.66, 0.69; CHB linked records aOR = 0.17, 95 %CI = 0.11, 0.25). Of the 6118 infants linked to a positive maternal record of CHB, discrepant recording of maternal CHB status between the three datasets was identified in 72.4% of records and HBIG administration was recorded for only 2.3% of births. CONCLUSION: An approach that involves coordinated care and integrates data collection for women with CHB and their infants is required to support the elimination of MTCT of hepatitis B in Victoria.

Modelling jurisdictional disparities in the cascade of care for chronic hepatitis B in Australia: impact of treatment uptake on mortality.

OBJECTIVE: Investigate the cascade of care for chronic hepatitis B (CHB) and estimate impacts of increasing treatment uptake on attributable burden, according to jurisdiction. METHODS: A mathematical model of CHB in Australia was utilised, combined with notifiable disease and Medicare data. We estimated the proportion with CHB who were diagnosed, engaged in care and receiving treatment in each state/territory, and projected future mortality. RESULTS: The highest uptake of all measures was in New South Wales, however, the largest increase over time occurred in Northern Territory. No jurisdiction is due to meet 2022 targets of treatment uptake or mortality reduction. Previously declining mortality is predicted to plateau or increase in all jurisdictions except Northern Territory. The largest gap in the cascade of care was most commonly diagnosed individuals not engaged in care; however, in Victoria and Tasmania it was lack of diagnosis. CONCLUSIONS: Measures of the cascade of care varied substantially between jurisdictions; while all require improvements to reduce mortality, the specific gaps vary, as do potential impacts. IMPLICATIONS FOR PUBLIC HEALTH: Improving the cascade of care for CHB will require jurisdictionally tailored approaches. If improvements are not made, more deaths will occur due to CHB in most states and territories.

Post-COVID-19 syndrome/condition or long COVID: Persistent illness after acute SARS CoV-2 infection.

BACKGROUND: Approximately 10 million Australians have had confirmed SARS-CoV-2 infection. The waves of infection in the population have been succeeded by smaller waves of people affected by persistent illness following acute infection. Post-COVID-19 symptoms may extend for months following infection. There is a range of symptoms causing mild to debilitating impairment. OBJECTIVE: This article summarises what is currently understood about the pathophysiology, risk factors, symptoms and how to approach both the assessment and care of people with post-COVID-19 sequelae. DISCUSSION: Currently recommended is a person-centred approach from a multidisciplinary team, with general practitioners centrally coordinating care. As the understanding of post-acute COVID-19 is evolving, regularly updated or 'living guidelines' will be crucial for those affected to be provided with best care within the health system.

Women with hepatitis B: how mothers with chronic hepatitis B understand and experience the prevention of mother-to-child transmission interventions in Victoria, Australia.

BACKGROUND: Mother-to-child transmission (MTCT) of hepatitis B can be prevented with targeted interventions; however, MTCT continues to occur in Australia and globally. This qualitative research investigated how mothers with chronic hepatitis B (CHB) understand and experience interventions for the prevention of MTCT of CHB (PMTCT-CHB) in Victoria, Australia. METHODS: Semi-structured interviews were conducted with women with CHB. Participants were recruited through purposive and snowballing sampling. Interviews explored the women's experience of care for themselves and their infants aimed at PMTCT-CHB. Interviews were conducted over the phone with a qualified interpreter where required. The consolidated criteria for reporting qualitative research framework was used with data thematically analysed. This study was co-designed with mothers with CHB through a Community Advisory Group established for this research; coordinated and supported by LiverWELL and the researchers. RESULTS: Sixteen women were interviewed. Although most women understood the purpose of hepatitis B vaccination, there were significant gaps in information and education provided to mothers regarding PMTCT-CHB. These gaps included understanding of the extent of protection of vaccination, breastfeeding with CHB, post-vaccination testing for infants and lack of clarity of the woman's own hepatitis B status. There was notable fear and worry associated with hepatitis B transmission, with emotional support for mothers identified as a major gap in service delivery. Additionally, some women experienced stigma and discrimination due to their hepatitis B and refugee status. CONCLUSIONS: This study explored how mothers with CHB understand and experience interventions to prevent MTCT. Our findings reveal substantial gaps in delivery of information and care in the context of PMTCT-CHB in Victoria. Our findings can support development of evidence-based interventions and systems to improve healthcare for mothers with CHB and their infants, and thereby reduce possible CHB transmission and other negative outcomes, including stigma and discrimination.

Australian consensus recommendations for the management of hepatitis B.

INTRODUCTION: The prevalence of hepatitis B virus (HBV) infection in Australia is nearly 1%. In certain well defined groups the prevalence is far greater, yet an estimated 27% of people living with HBV infection remain undiagnosed. Appropriate screening improves detection, increases opportunity for treatment, and ultimately reduces the significant morbidity and mortality associated with the development of liver fibrosis and hepatocellular carcinoma (HCC). MAIN RECOMMENDATIONS: This statement highlights important aspects of HBV infection management in Australia. There have been recent changes in nomenclature and understanding of natural history, as well as a newly defined upper limit of normal for liver tests that determine phase classification and threshold for antiviral treatment. As the main burden of hepatitis B in Australia is within migrant and Indigenous communities, early identification and management of people living with hepatitis B is essential to prevent adverse outcomes including liver cancer and cirrhosis. CHANGE IN MANAGEMENT AS A RESULT OF THIS GUIDELINE: These recommendations aim to raise awareness of the current management of hepatitis B in Australia. Critically, the timely identification of individuals living with hepatitis B, and where appropriate, commencement of antiviral therapy, can prevent the development of cirrhosis, HCC and mother-to-child transmission as well as hepatitis B reactivation in immunocompromised individuals. Recognising patient and viral factors that predispose to the development of cirrhosis and HCC will enable clinicians to risk-stratify and appropriately implement surveillance strategies to prevent these complications of hepatitis B.

Understanding how to live with hepatitis B: a qualitative investigation of peer advice for Chinese people living with hepatitis B in Australia.

BACKGROUND: Hepatitis B is a chronic viral infection, a leading cause of primary liver cancer and identified as a major public health priority by the World Health Organization. Despite a high proportion of people in Australia who have been diagnosed with hepatitis B, significant gaps remain in health care access and in accurate knowledge about hepatitis B. Most people with hepatitis B in Australia were born in China, where the infection has an intergenerational impact with significant social implications resulting from the infection. Understanding how people of Chinese ethnicity with hepatitis B understand and respond to hepatitis B is imperative for reducing morbidity, mortality, and the personal and social impact of the infection. METHODS: Qualitative semi-structured interviews with people with hepatitis B of Chinese ethnicity recruited through a specialist service identified the advice people with hepatitis B thought was important enough to inform the experience of people newly diagnosed with hepatitis B. A thematic analysis of the data privileged the lived experience of participants and their personal, rather than clinical, explanations of the virus. RESULTS: Hepatitis B infection had psychological and physical consequences that were informed by cultural norms, and to which people had responded to with significant behavioural change. Despite this cohort being engaged with specialist clinical services with access to the most recent, comprehensive, and expert information, much of the advice people with hepatitis B identified as important for living with hepatitis B was not based on biomedical understandings. Key suggestions from people with hepatitis B were to form sustainable clinical relationships, develop emotional resilience, make dietary changes, regulate energy, and issues related to disclosure. CONCLUSIONS: The study highlights conflicts between biomedical and public health explanations and the lived experience of hepatitis B among people of Chinese ethnicity in Australia. Beliefs about hepatitis B are embedded within cultural understandings of health that can conflict with bio-medical explanations of the infection. Acknowledging these perspectives provides for insightful communication between health services and their clients, and the development of nuanced models of care informed by the experience of people with hepatitis B.

The COVID Positive Pathway: a collaboration between public health agencies, primary care, and metropolitan hospitals in Melbourne.

OBJECTIVES: To assess the capacity of the COVID Positive Pathway, a collaborative model of care involving the Victorian public health unit, hospital services, primary care, community organisations, and the North Western Melbourne Primary Health Network, to support people with coronavirus disease 2019 (COVID-19) isolating at home. DESIGN, SETTING, PARTICIPANTS: Cohort study of adults in northwest Melbourne with COVID-19, 3 August - 31 December 2020. MAIN OUTCOME MEASURES: Demographic and clinical characteristics, and social and welfare needs of people cared for in the Pathway, by care tier level. RESULTS: Of 1392 people referred to the Pathway by the public health unit, 858 were eligible for enrolment, and 711 consented to participation; 647 (91%) remained in the Pathway until they had recovered and isolation was no longer required. A total of 575 participants (81%) received care in primary care, mostly from their usual general practitioners; 155 people (22%) received care from hospital outreach services, and 64 (9%) needed high tier care (hospitalisation). Assistance with food and other basic supplies was required by 239 people in the Pathway (34%). CONCLUSIONS: The COVID Positive Pathway is a feasible multidisciplinary, tiered model of care for people with COVID-19. About 80% of participants could be adequately supported by primary care and community organisations, allowing hospital services to be reserved for people with more severe illness or with risk factors for disease progression. The principles of this model could be applied to other health conditions if regulatory and funding barriers to information-sharing and care delivery by health care providers can be overcome.

Adding saliva testing to oropharyngeal and deep nasal swab testing increases PCR detection of SARS-CoV-2 in primary care and children.

OBJECTIVE: To compare the concordance and acceptability of saliva testing with standard-of-care oropharyngeal and bilateral deep nasal swab testing for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in children and in general practice. DESIGN: Prospective multicentre diagnostic validation study. SETTING: Royal Children's Hospital, and two general practices (cohealth, West Melbourne; Cirqit Health, Altona North) in Melbourne, July-October 2020. PARTICIPANTS: 1050 people who provided paired saliva and oropharyngeal-nasal swabs for SARS-CoV-2 testing. MAIN OUTCOME MEASURES: Numbers of cases in which SARS-CoV-2 was detected in either specimen type by real-time polymerase chain reaction; concordance of results for paired specimens; positive percent agreement (PPA) for virus detection, by specimen type. RESULTS: SARS-CoV-2 was detected in 54 of 1050 people with assessable specimens (5%), including 19 cases (35%) in which both specimens were positive. The overall PPA was 72% (95% CI, 58-84%) for saliva and 63% (95% CI, 49-76%) for oropharyngeal-nasal swabs. For the 35 positive specimens from people aged 10 years or more, PPA was 86% (95% CI, 70-95%) for saliva and 63% (95% CI, 45-79%) for oropharyngeal-nasal swabs. Adding saliva testing to standard-of-care oropharyngeal-nasal swab testing increased overall case detection by 59% (95% CI, 29-95%). Providing saliva was preferred to an oropharyngeal-nasal swab by most participants (75%), including 141 of 153 children under 10 years of age (92%). CONCLUSION: In children over 10 years of age and adults, saliva testing alone may be suitable for SARS-CoV-2 detection, while for children under 10, saliva testing may be suitable as an adjunct to oropharyngeal-nasal swab testing for increasing case detection.

Hepatitis B in the Northern Territory: insights into the changing epidemiology of an ancient condition.

BACKGROUND: Aboriginal and Torres Strait Islander people are disproportionately affected by hepatitis B virus (HBV) infection. A proposed mismatch between standard vaccines and the HBV/C4 sub-genotype prevalent in Aboriginal people in the Northern Territory (NT) may reduce vaccine effectiveness. AIMS: To determine HBV prevalence in the NT by Indigenous status and to explore patterns of immunity following implementation of universal vaccination, using a large longitudinal diagnostic dataset. METHODS: A retrospective analysis of all available HBV serology results in the NT from 1991 to 2011 was conducted, with HBV prevalence and vaccination status analysed according to adigenous status, age and sex using individuals' patterns of HBsAg, anti-HBs and anti-HBc serology over repeated tests. RESULTS: 100 790 individuals were tested (33.4% Indigenous) between 1991 and 2011 (26.1% of the 2011 NT population), with a total of 211 802 tests performed. In 2011, the proportion of HBV positive individuals in the NT was 3.17% (5.22% in Indigenous populations) compared to previous 2011 estimates of 1.70% (3.70% in Indigenous populations). The vaccine failure rate was lower than expected with only one presumed vaccinated person subsequently developing HBsAg positivity (0.02%). Evidence of suboptimal vaccine efficacy by breakthrough anti-HBc positivity in vaccinated individuals was demonstrated in 3.1% of the vaccinated cohort, of which 86.4% identified as Indigenous (HR 1.17). No difference in HBeAg positivity or seroconversion was observed between Indigenous and non-Indigenous individuals living with CHB. CONCLUSIONS: The burden of CHB in Indigenous people in the NT has previously been underestimated. A higher HBV prevalence in the NT than described in previous cross-sectional studies was found, including a higher prevalence in Indigenous people. Evidence of suboptimal vaccine efficacy was demonstrated predominantly in Indigenous individuals.