Measuring quality of hepatitis B care in a remote Australian Aboriginal community: opportunities for improvement

BACKGROUND

Chronic hepatitis B (CHB) infection remains a significant public health issue for Indigenous Australians, in particular for remote communities.

AIM

To evaluate the spectrum of hepatitis B virus (HBV) care provided to a remote Aboriginal community. Measures studied included screening, seroprevalence, vaccination rates and efficacy, and HCC risk and surveillance adherence.

METHODS

A retrospective audit of HBV care received by all permanent residents currently attending a remote Aboriginal Health service. This study was endorsed by both the local Aboriginal Health service and the Aboriginal Health Council of South Australia.

RESULTS

A total of 208 patients attended the clinic, of whom 52% (109) were screened for HBV. Of these, 12% (13) had CHB and 20% (22) had evidence of past infection. Similarly, of the 208 attending patients, complete vaccination was documented in 48% (99). Of the 33 patients with post-vaccination serology, 24% (8) had subtherapeutic (<10 IU/mL) levels of HBsAb. Subtherapeutic HBsAb was independently associated with higher Charlson Comorbidity scores (odds ratio = 17.1; 95% confidence interval 1.2-243.3; P = 0.036). Definitive breakthrough infection was identified in 6% (2) patients. One HBsAg positive patient was identified as needing HCC surveillance, but had not undertaken HCC surveillance.

CONCLUSION

Opportunities to improve the quality of CHB care through increased HBV vaccination, screening and adherence to HCC surveillance were identified. High rates of subtherapeutic vaccine responses and documented breakthrough infection raises concerns about the effectiveness of current CHB vaccines in this population.

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.

Hepatitis B prophylaxis in adolescents who present for examination after alleged sexual assault

AIM

In Australia, the risk of hepatitis B virus (HBV) transmission from single sexual contact is low. This, combined with assumed widespread immunity from vaccination, has resulted in a lack of clarity surrounding the necessity for hepatitis B post-exposure prophylaxis following recent sexual assault.

METHODS

This retrospective audit was conducted through the Victorian Forensic Paediatric Medical Service (VFPMS) at the Royal Children's Hospital, Melbourne, Australia. Subjects were patients aged 13-17 years who presented to VFPMS between 1 January 2007 and 31 December 2016 for forensic medical examination following an alleged penetrative sexual assault. Data collected included subject demographics, immunisation status, route of potential HBV exposure, time between alleged sexual assault and presentation, whether HBsAb levels were tested and the results and whether HBV prophylaxis was administered to the subject and its timing.

RESULTS

A total of 2121 records were reviewed, and 420 subjects were found to be eligible for inclusion; 26.2% (n = 110) had HBsAb levels measured at initial presentation. Of these 110 subjects, 45.5% (n = 50) had titre levels less than 10 (deemed to be non-protective) and were therefore vulnerable to HBV infection. Of the 420 subjects, 4.5% (n = 19) received HBV prophylaxis as a result of their assessment.

CONCLUSIONS

Results suggest that a high proportion of Australian adolescents presenting following recent sexual assault may be at risk of hepatitis B infection. Very few received timely prophylaxis. Follow-up attendance rates were poor. Administration of the hepatitis B booster vaccine at the point of contact may reduce the risk of HBV infection in this group of adolescents.

In silico Analysis of Genetic Diversity of Human Hepatitis B Virus in Southeast Asia, Australia and New Zealand

The extent of whole genome diversity amongst hepatitis B virus (HBV) genotypes is not well described. This study aimed to update the current distribution of HBV types and to investigate mutation rates and nucleotide diversity between genotypes in Southeast Asia, Australia and New Zealand. We retrieved 930 human HBV complete genomes from these regions from the NCBI nucleotide database for genotyping, detection of potential recombination, serotype prediction, mutation identification and comparative genome analyses. Overall, HBV genotypes B (44.1%) and C (46.2%) together with predicted serotypes adr (36%), adw2 (29%) and ayw1 (19.9%) were the most commonly circulating HBV types in the studied region. The three HBV variants identified most frequently were p.V5L, c.1896G>A and double mutation c.1762A>T/c.1764G>A, while genotypes B and C had the widest range of mutation types. The study also highlighted the distinct nucleotide diversity of HBV genotypes for whole genome and along the genome length. Therefore, this study provided a robust update to HBV currently circulating in Southeast Asia, Australia and New Zealand as well as an insight into the association of HBV genetic hypervariability and prevalence of well reported mutations.

Long-term impact of infant immunization on hepatitis B prevalence: a systematic review and meta-analysis

OBJECTIVE

To conduct a systematic review and meta-analysis of the long-term impact of infant vaccination on the prevalence of hepatitis B virus (HBV) infection at the population level.

METHODS

We searched online databases for articles reporting comparisons between population cohorts aged ≥ 15 years who were exposed or unexposed to infant HBV immunization programmes. We categorized programmes as universal or targeted to infants whose mothers were positive for hepatitis B surface antigen (HBsAg). We included studies reporting prevalence of hepatitis B core antibody (HBcAb), HBsAg, or both. We evaluated the quality of the study methods and estimated the relative reduction in the prevalence of infection.

FINDINGS

Of 26 studies that met the inclusion criteria, most were from China (20 studies). The prevalence of HBV infection in unvaccinated and universally vaccinated cohorts ranged from 0.6% (116 of 20 305 people) to 16.3% (60/367) and from 0.3% (1/300) to 8.5% (73/857), respectively. Comparing cohorts with universal vaccination to those without vaccination, relative prevalences were 0.24 (95% confidence interval, CI: 0.16-0.35) for HBsAg and 0.23 (95% CI: 0.17-0.32) for HBcAb. For populations with targeted vaccination, relative prevalences were 0.32 (95% CI: 0.24-0.43) and 0.33 (95% CI: 0.23-0.45), respectively.

CONCLUSION

The residual burden of infection in cohorts offered vaccination suggests that longer-term evaluations of vaccination coverage, timeliness and other aspects of programme quality are needed. As HBV-vaccinated infant cohorts reach adulthood, ongoing analysis of prevalence in adolescents and young adults will ensure that elimination efforts are on track.