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

Ashleigh Qama; Nicole Allard; Benjamin Cowie; Joshua S. Davis; Jane Davies

doi:10.1111/imj.15069

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

Ashleigh Qama, Nicole Allard, Benjamin Cowie, Joshua S. Davis, Jane Davies

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Abstract

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 Indigenous 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.

Original language	English
Pages (from-to)	910-922
Number of pages	13
Journal	Internal Medicine Journal
Volume	51
Issue number	6
DOIs	https://doi.org/10.1111/imj.15069
Publication status	Published - Jun 2021

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44787599-oaFinal published version, 1.45 MBLicence: CC BY-NC

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@article{f4ccc5ed4d674530a429399a846ccbe7,

title = "Hepatitis B in the Northern Territory: Insights into the changing epidemiology of an ancient condition",

abstract = "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 Indigenous 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.",

keywords = "Aboriginal and Torres Strait islander peoples, chronic hepatitis B, hepatitis B virus, infant vaccination, vaccine efficacy",

author = "Ashleigh Qama and Nicole Allard and Benjamin Cowie and Davis, {Joshua S.} and Jane Davies",

note = "Funding Information: None.We acknowledge the traditional custodians of the lands where this research was undertaken. We thank the patients whose data contributed to this work. We also thank Dr Margaret Littlejohn and Professor Peter Revill for their insights relating to anti-HBc positivity in vaccinated individuals. Publisher Copyright: {\textcopyright} 2020 The Authors. Internal Medicine Journal published by John Wiley & Sons Australia, Ltd on behalf of Royal Australasian College of Physicians. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.",

year = "2021",

month = jun,

doi = "10.1111/imj.15069",

language = "English",

volume = "51",

pages = "910--922",

journal = "Internal Medicine Journal",

issn = "1444-0903",

publisher = "Wiley-Blackwell",

number = "6",

}

TY - JOUR

T1 - Hepatitis B in the Northern Territory

T2 - Insights into the changing epidemiology of an ancient condition

AU - Qama, Ashleigh

AU - Allard, Nicole

AU - Cowie, Benjamin

AU - Davis, Joshua S.

AU - Davies, Jane

N1 - Funding Information: None.We acknowledge the traditional custodians of the lands where this research was undertaken. We thank the patients whose data contributed to this work. We also thank Dr Margaret Littlejohn and Professor Peter Revill for their insights relating to anti-HBc positivity in vaccinated individuals. Publisher Copyright: © 2020 The Authors. Internal Medicine Journal published by John Wiley & Sons Australia, Ltd on behalf of Royal Australasian College of Physicians. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/6

Y1 - 2021/6

N2 - 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 Indigenous 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.

AB - 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 Indigenous 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.

KW - Aboriginal and Torres Strait islander peoples

KW - chronic hepatitis B

KW - hepatitis B virus

KW - infant vaccination

KW - vaccine efficacy

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U2 - 10.1111/imj.15069

DO - 10.1111/imj.15069

M3 - Article

C2 - 32975893

AN - SCOPUS:85108211995

VL - 51

SP - 910

EP - 922

JO - Internal Medicine Journal

JF - Internal Medicine Journal

SN - 1444-0903

IS - 6

ER -

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

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