Removing hepatitis C antibody testing for Australian blood donations: A cost-effectiveness analysis.

BACKGROUND AND OBJECTIVES: The risk of transfusion-transmitted hepatitis C virus (HCV) infections is extremely low in Australia. This study aims to conduct a cost-effectiveness analysis of different testing strategies for HCV infection in blood donations. MATERIALS AND METHODS: The four testing strategies evaluated in this study were universal testing with both HCV antibody (anti-HCV) and nucleic acid testing (NAT); anti-HCV and NAT for first-time donations and NAT only for repeat donations; anti-HCV and NAT for transfusible component donations and NAT only for plasma for further manufacture; and universal testing with NAT only. A decision-analytical model was developed to assess the cost-effectiveness of alternative HCV testing strategies. Sensitivity analysis and threshold analysis were conducted to account for data uncertainty. RESULTS: The number of potential transfusion-transmitted cases of acute hepatitis C and chronic hepatitis C was approximately zero in all four strategies. Universal testing with NAT only was the most cost-effective strategy due to the lowest testing cost. The threshold analysis showed that for the current practice to be cost-effective, the residual risks of other testing strategies would have to be at least 1 HCV infection in 2424 donations, which is over 60,000 times the baseline residual risk (1 in 151 million donations). CONCLUSION: The screening strategy for HCV in blood donations currently implemented in Australia is not cost-effective compared with targeted testing or universal testing with NAT only. Partial or total removal of anti-HCV testing would bring significant cost savings without compromising blood recipient safety.

A HIV diagnosis and treatment cascade for Aboriginal and Torres Strait Islander peoples of Australia.

Aboriginal and Torres Strait Islander (hereafter Aboriginal) people are a priority population for HIV care in Australia; however, no HIV cascade exists for this population. We developed annual HIV cascades for 2010-2017 specific to Aboriginal peoples. By 2017, an estimated 595 Aboriginal people were living with HIV (PLWH); however, 14% remained undiagnosed. Cascade steps below global targets were: PLWH aware of their diagnosis (86%), and retention in care (81% of those who had received any care in previous two years in a sentinel network of clinics). For people retained in care, treatment outcomes surpassed global targets (92% receiving treatment, 93% viral suppression). Increases occurred across all HIV cascade steps over time; however, the least improvement was for retention in care, while the greatest improvement was achieving viral suppression. The HIV cascade for Aboriginal peoples highlights both gaps and strengths in the Australian HIV care system, and importantly highlights where potential interventions may be required to achieve the global UNAIDS targets.

Impact of increased antiretroviral therapy use during the treatment as prevention era in Australia.

BACKGROUND: We analysed the impact of increased antiretroviral therapy (ART) on HIV epidemiology and healthcare costs in Australia during the 'Treatment-as-prevention' and 'Undetectable equals Untransmissible (U=U)' eras. METHODS: We conducted a retrospective modelling analysis between 2009 and 2019 to calculate the potential impact of early initiation of ART and treatment-as-prevention on HIV among gay and bisexual men (GBM). The model incorporates the change in the proportion diagnosed, treated, and virally suppressed, as well as the scale-up of oral HIV pre-exposure prophylaxis (PrEP) and the change in sexual behaviour during this period. We simulated a baseline and a no ART increase scenario and conducted a costing analysis from a national health provider perspective with cost estimates in 2019 AUD. RESULTS: Increasing ART use between 2009 and 2019 averted an additional 1624 [95% percentile interval (PI): 1220-2099] new HIV infections. Without the increase in ART, the number of GBM with HIV would have increased from 21 907 (95% PI: 20 753-23 019) to 23 219 (95% PI: 22 008-24 404) by 2019. HIV care and treatment costs for people with HIV increased by $296 (95% PI: $235-367) million AUD (assuming no change in annual healthcare costs). This was offset by a decrease in the lifetime HIV costs (with 3.5% discounting) for those newly infected of $458 (95% PI: $344-592) million AUD, giving a net cost saving of $162 (95%: $68-273) million AUD (and a benefits-to-cost ratio of 1.54). CONCLUSIONS: Increasing the proportion of Australian GBM on effective ART between 2009 and 2019 likely resulted in substantial reductions in new HIV infections and cost savings.

A Gonococcal Vaccine Has the Potential to Rapidly Reduce the Incidence of Neisseria gonorrhoeae Infection Among Urban Men Who Have Sex With Men.

BACKGROUND: A gonococcal vaccine is urgently needed due to increasing gonorrhea incidence and emerging multidrug-resistant gonococcal strains worldwide. Men who have sex with men (MSM) have among the highest incidences of gonorrhea and may be a key target population for vaccination when available. METHODS: An individual-based, anatomical site-specific mathematical model was used to simulate Neisseria gonorrhoeae transmission in a population of 10 000 MSM. The impact of vaccination on gonorrhea prevalence was assessed. RESULTS: With a gonococcal vaccine of 100% or 50% protective efficacy, gonorrhea prevalence could be reduced by 94% or 62%, respectively, within 2 years if 30% of MSM are vaccinated on presentation for sexually transmitted infection (STI) testing. Elimination of gonorrhea is possible within 8 years with vaccines of ≥ 50% efficacy lasting 2 years, providing a booster vaccination is available every 3 years on average. A vaccine's impact may be reduced if it is not effective at all anatomical sites. CONCLUSIONS: Our study indicates that with a vaccine of modest efficacy and an immunization strategy that targets MSM presenting for STI screening, the prevalence of gonorrhea in this population could be rapidly and substantially reduced.

Assessing the Impact of HIV Preexposure Prophylaxis Scale-Up on Gonorrhea Incidence Among Gay and Bisexual Men in Sydney: A Mathematical Modeling Study.

BACKGROUND: The rollout of preexposure prophylaxis (PrEP) for HIV prevention among gay and bisexual men (GBM) is associated with increases in condomless anal intercourse, potentially increasing the incidence of other sexually transmissible infections (STIs). METHODS: We developed an individual-based mathematical model to simulate the transmission of Neisseria gonorrhoeae among GBM in Sydney, accounting for changes in sexual practices, STI testing, and PrEP use. We calibrated and validated the model using reported incidence rates for HIV-positive and HIV-negative GBM from 2010 to 2019. Scenarios were run with varying PrEP uptake, PrEP-related STI testing, and PrEP-related sexual behavior and testing intervals up to 2030 to assess the impact of PrEP use on gonorrhea incidence. RESULTS: Preexposure prophylaxis uptake and associated 3-monthly STI testing from 2015 onward resulted in a predicted increase from 20 to 37 N. gonorrhoeae infections per 100 person-years among HIV-negative GBM by the end of 2020. This is lower than the counterfactual predictions of 45 per 100 person-years if PrEP were not scaled up and 48 per 100 person-years with nonadherence to 3-monthly STI testing. Increasing the time between STI tests for PrEP users by 1 month from 2018 results in the incidence rate among HIV-negative GBM increasing by 8% by 2030. If PrEP coverage doubles from 24% to 53%, incidence among HIV-negative GBM declines by ~25% by 2030. CONCLUSIONS: Behavior change due to widespread PrEP use may lead to significant increases in gonorrhea incidence in GBM, but the recommended quarterly STI testing recommended for PrEP users should reduce incidence by 18% by 2030.

Can Australia Reach the World Health Organization Hepatitis C Elimination Goal by 2025 Among Human Immunodeficiency Virus-positive Gay and Bisexual Men?

BACKGROUND: Human immunodeficiency virus (HIV)-positive gay and bisexual men (GBM) in Australia are well engaged in care. The World Health Organization's (WHO) hepatitis C virus (HCV) elimination target of an 80% reduction in incidence by 2030 may be reachable ahead of time in this population. METHODS: We predicted the effect of treatment and behavioral changes on HCV incidence among HIV-positive GBM up to 2025 using a HCV transmission model parameterized with Australian data. We assessed the impact of changes in behavior that facilitate HCV transmission in the context of different rates of direct-acting antiviral (DAA) use. RESULTS: HCV incidence in our model increased from 0.7 per 100 person-years in 2000 to 2.5 per 100 person-years in 2016 and had the same trajectory as previously reported clinical data. If the proportion of eligible (HCV RNA positive) patients using DAAs stays at 65% per year between 2016 and 2025, with high-risk sexual behavior and injecting drug use remaining at current levels, HCV incidence would drop to 0.4 per 100 person-years (85% decline from 2016). In the same treatment scenario but with substantial increases in risk behavior, HCV incidence would drop to 0.6 per 100 person-years (76% decline). If the proportion of eligible patients using DAAs dropped from 65% per year in 2016 to 20% per year in 2025 and risk behavior did not change, HCV incidence would drop to 0.7 per 100 person-years (70% reduction). CONCLUSIONS: Reaching the WHO HCV elimination target by 2025 among HIV-positive GBM in Australia is achievable.

Gaps in the HIV diagnosis and care cascade for migrants in Australia, 2013-2017: A cross-sectional study.

BACKGROUND: Globally, few studies compare progress toward the Joint United Nations Program on HIV/AIDS (UNAIDS) Fast-Track targets among migrant populations. Fast-Track targets are aligned to the HIV diagnosis and care cascade and entail achieving 90-90-90 (90% of people living with HIV [PLHIV] diagnosed, 90% of those diagnosed on treatment, and 90% of those on treatment with viral suppression [VS]) by 2020 and 95-95-95 by 2030. We compared cascades between migrant and nonmigrant populations in Australia. METHODS AND FINDINGS: We conducted a serial cross-sectional survey for HIV diagnosis and care cascades using modelling estimates for proportions diagnosed combined with a clinical database for proportions on treatment and VS between 2013-2017. We estimated the number of PLHIV and number diagnosed using New South Wales (NSW) and Victorian (VIC) data from the Australian National HIV Registry. Cascades were stratified by migration status, sex, HIV exposure, and eligibility for subsidised healthcare in Australia (reciprocal healthcare agreement [RHCA]). We found that in 2017, 17,760 PLHIV were estimated in NSW and VIC, and 90% of them were males. In total, 90% of estimated PLHIV were diagnosed. Of the 9,391 who were diagnosed and retained in care, most (85%; n = 8,015) were males. We excluded 38% of PLHIV with missing data for country of birth, and 41% (n = 2,408) of eligible retained PLHIV were migrants. Most migrants were from Southeast Asia (SEA; 28%), northern Europe (12%), and eastern Asia (11%). Most of the migrants and nonmigrants were males (72% and 83%, respectively). We found that among those retained in care, 90% were on antiretroviral therapy (ART), and 95% of those on ART had VS (i.e., 90-90-95). Migrants had larger gaps in their HIV diagnosis and care cascade (85-85-93) compared with nonmigrants (94-90-96). Similarly, there were larger gaps among migrants reporting male-to-male HIV exposure (84-83-93) compared with nonmigrants reporting male-to-male HIV exposure (96-92-96). Large gaps were also found among migrants from SEA (72-87-93) and sub-Saharan Africa (SSA; 89-93-91). Migrants from countries ineligible for RHCA had lower cascade estimates (83-85-92) than RHCA-eligible migrants (96-86-95). Trends in the HIV diagnosis and care cascades improved over time (2013 and 2017). However, there was no significant increase in ART coverage among migrant females (incidence rate ratio [IRR]: 1.03; 95% CI 0.99-1.08; p = 0.154), nonmigrant females (IRR: 1.01; 95% CI 0.95-1.07; p = 0.71), and migrants from SEA (IRR: 1.03; 95% CI 0.99-1.07; p = 0.06) and SSA (IRR: 1.03; 95% CI 0.99-1.08; p = 0.11). Additionally, there was no significant increase in VS among migrants reporting male-to-male HIV exposure (IRR: 1.02; 95% CI 0.99-1.04; p = 0.08). The major limitation of our study was a high proportion of individuals missing data for country of birth, thereby limiting migrant status categorisation. Additionally, we used a cross-sectional instead of a longitudinal study design to develop the cascades and used the number retained as opposed to using all individuals diagnosed to calculate the proportions on ART. CONCLUSIONS: HIV diagnosis and care cascades improved overall between 2013 and 2017 in NSW and VIC. Cascades for migrants had larger gaps compared with nonmigrants, particularly among key migrant populations. Tracking subpopulation cascades enables gaps to be identified and addressed early to facilitate achievement of Fast-Track targets.

Population-level diagnosis and care cascade for chlamydia in Australia.

OBJECTIVES: Key strategies to control chlamydia include testing, treatment, partner management and re-testing. We developed a diagnosis and care cascade for chlamydia to highlight gaps in control strategies nationally and to inform efforts to optimise control programmes. METHODS: The Australian Chlamydia Cascade was organised into four steps: (1) annual number of new chlamydia infections (including re-infections); (2) annual number of chlamydia diagnoses; (3) annual number of diagnoses treated; (4) annual number of diagnoses followed by a re-test for chlamydia within 42-180 days of diagnosis. For 2016, we estimated the number of infections among young men and women aged 15-29 years in each of these steps using a combination of mathematical modelling, national notification data, sentinel surveillance data and previous research studies. RESULTS: Among young people in Australia, there were an estimated 248 580 (range, 240 690-256 470) new chlamydia infections in 2016 (96 470 in women; 152 100 in men) of which 70 164 were diagnosed (28.2% overall: women 43.4%, men 18.6%). Of the chlamydia infections diagnosed, 65 490 (range, 59 640-70 160) were treated (93.3% across all populations), but only 11 330 (range, 7660-16 285) diagnoses were followed by a re-test within 42-180 days (17.3% overall: women 20.6%, men 12.5%) of diagnosis. CONCLUSIONS: The greatest gaps in the Australian Chlamydia Cascade for young people were in the diagnosis and re-testing steps, with 72% of infections undiagnosed and 83% of those diagnosed not re-tested: both were especially low among men. Treatment rates were also lower than recommended by guidelines. Our cascade highlights the need for enhanced strategies to improve treatment and re-testing coverage such as short message service reminders, point-of-care and postal test kits.

Australia on track to achieve WHO HCV elimination targets following rapid initial DAA treatment uptake: A modelling study.

Subsidized direct-acting antiviral (DAA) treatment recently became available to all adults living with chronic hepatitis C virus (HCV) in Australia. Based on rapid uptake (32 600 people initiated DAA in 2016), we estimated the impact on HCV epidemiology and mortality in Australia and determined if Australia can meet the WHO HCV elimination targets by 2030. Using a mathematical model, we simulated pessimistic, intermediate and optimistic DAA treatment scenarios in Australia over 2016-2030. We assumed treatment and testing rates were initially higher for advanced fibrosis and the same across HCV transmission risk level sub-populations. We also assumed constant testing rates after 2016. We compared the results to the 2015 level and a counterfactual (IFN-based) scenario. During 2016-2030, we estimated an intermediate DAA treatment scenario (2016, 32 600 treated; 2017, 21 370 treated; 2018 17 100 treated; 2019 and beyond, 13 680 treated each year) would avert 40 420 new HCV infections, 13 260 liver-related deaths (15 320 in viraemic; -2060 in cured) and 10 730 HCC cases, equating to a 53%, 63% and 75% reduction, respectively, compared to the IFN-based scenario. The model also estimated that Australia will meet the WHO targets of incidence and treatment by 2028. Time to a 65% reduction in liver-related mortality varied considerably between HCV viraemic only cases (2026) and all cases (2047). Based on a feasible DAA treatment scenario incorporating declining uptake, Australia should meet key WHO HCV elimination targets in 10 to15 years. The pre-DAA escalation in those with advanced liver disease makes the achievement of the liver-related mortality target difficult.

HIV treatment regimens and adherence to national guidelines in Australia: an analysis of dispensing data from the Australian pharmaceutical benefits scheme.

BACKGROUND: Treatment guidelines for antiretroviral therapy (ART) have evolved to emphasize newer regimens that address ageing-related comorbidities. Using national Australian dispensing data we compare ART regimens with Australian HIV treatment guidelines in the context of treated comorbidities. METHODS: The study population included all individuals in a 10% sample of national data from the Australian Pharmaceutical Benefits Scheme (PBS) who purchased a prescription of ART during 2016. We defined each patient's most recently dispensed ART regimen and characterized them to evaluate regimen complexity and adherence to national HIV treatment guidelines. We then analyzed ART regimens in the context of other co-prescriptions purchased for defined comorbidities. RESULTS: The 1995 patients in our sample purchased 212 different ART regimens during 2016; 1524 (76.4%) purchased one of the top ten most common regimens of which 62.3% were integrase strand transfer inhibitor-based. Among the 1786 (90%) patients that purchased the most common regimens, 83.7% purchased a regimen recommended by the guidelines for initial antiretroviral therapy and 11.4% purchased antiretrovirals that are not recommended for initial therapy; < 1% of the entire cohort purchased medications not recommended for use. While most patients purchased optimal ART regimens with low potential for significant drug interactions, regimen choices in the setting of risk factors for heart disease, renal disease and low bone mineral density appeared suboptimal. CONCLUSIONS: Australian HIV providers are prescribing ART regimens in accordance with updated treatment guidelines, but could further optimize regimens in the setting of important medical comorbidities.

Chronic hepatitis C burden and care cascade in Australia in the era of interferon-based treatment.

BACKGROUND AND AIM: Interferon-free direct-acting antiviral regimens for hepatitis C virus (HCV) infection have been recently available in Australia, beginning a new era in clinical and public health management of HCV infection. This study provided updated estimates of the HCV infection care cascade and burden in Australia as a reliable platform for assessing the future impact of interferon-free therapies. METHODS: A modeling approach was applied to estimate the number of individuals living with chronic HCV infection and with various liver disease stages. Data from national registries of HCV notification and liver transplantation, literature review, and expert consensus informed the model parameters. HCV notification and Pharmaceutical Benefits Scheme data were used to estimate the number of HCV diagnosed individuals and treatment uptake. RESULTS: In 2014, an estimated 230 470 individuals (range: 180 490-243 990) were living with HCV, among whom 75% were diagnosed (n = 172 720; range: 156 720-188 770), 20% had ever received treatment (n = 45 000; range: 39 280-50 720), and 11% had been cured (n = 24 750; range: 21 520-27 990). Among individuals with HCV infection, the proportion with hepatic fibrosis stage ≥F3 doubled during the last decade, increasing from 9% (n = 18 580) in 2004 to 19% (n = 44,730) in 2014. Individuals initiating HCV treatment increased from 1100 in 1997 to 3840 in 2007, plateaued until 2010 and decreased to 2790 in 2014. CONCLUSIONS: The burden of HCV-related liver disease has increased markedly. Although the proportion diagnosed was high, treatment uptake remained low, with no increase over the last 7 years. Reducing the HCV burden in Australia requires scale-up of interferon-free HCV therapies.

Estimating the number of people who inject drugs in Australia.

BACKGROUND: Injecting drug use is associated with considerable morbidity and mortality. Estimates of the size of the population of people who inject drugs are critical to inform service planning and estimate disease burden due to injecting drug use. We aimed to estimate the size of the population of people who inject drugs in Australia. METHODS: We applied a multiplier method which used benchmark data (number of people in opioid substitution therapy (OST) on a snapshot day in 2014) and multiplied it by a factor derived from the prevalence of current OST among people who inject drugs participating in the Australian Needle and Syringe Program Survey in 2014. Estimates of the total population of people who inject drugs were calculated in each state and territory and summed to produce a national estimate. We used the sex and age group distribution seen in datasets relating to people who inject drugs to derive sex- and age-stratified estimates, and calculated prevalence per 1000 population. RESULTS: Between 68,000 and 118,000 people aged 15-64 years inject drugs in Australia. The population prevalence of injecting drug use was 6.0 (lower and upper uncertainty intervals of 4.3 and 7.6) per 1000 people aged 15-64 years. Injecting drug use was more common among men than women, and most common among those aged 35-44 years. Comparison of expected drug-related deaths based on these estimates to actual deaths suggest that these figures may be underestimates. CONCLUSIONS: These are the first indirect prevalence estimates of injecting drug use in Australia in over a decade. This work has identified that there are limited data available to inform estimates of this population. These estimates can be used as a basis for further work estimating injecting drug use in Australia.

A cost-effectiveness analysis of HIV preexposure prophylaxis for men who have sex with men in Australia.

BACKGROUND: Antiretroviral therapy (ART) used as preexposure prophylaxis (PrEP) by human immunodeficiency virus (HIV)-seronegative individuals reduces the risk of acquiring HIV. However, the population-level impact and cost-effectiveness of using PrEP as a public health intervention remains debated. METHODS: We used a stochastic agent-based model of HIV transmission and progression to simulate the clinical and cost outcomes of different strategies of providing PrEP to men who have sex with men (MSM) in New South Wales (NSW), Australia. Model outcomes were reported as incremental cost-effectiveness ratios (ICERs) in 2013 Australian dollars per quality-adjusted life-year gained (QALYG). RESULTS: The use of PrEP in 10%-30% of the entire NSW MSM population was projected to cost an additional $316-$952 million over the course of 10 years, and cost >$400 000 per QALYG compared with the status quo. Targeting MSM with sexual partners ranging between >10 to >50 partners within 6 months cost an additional $31-$331 million dollars, and cost >$110 000 per QALYG compared with the status quo. We found that preexposure prophylaxis is most cost-effective when targeted for HIV-negative MSM in a discordant regular partnership. The ICERs ranged between $8399 and $11 575, for coverage ranging between 15% and 30%, respectively. CONCLUSIONS: Targeting HIV-negative MSM in a discordant regular partnership is a cost-effective intervention. However, this highly targeted strategy would not have large population-level impact. Other scenarios are unlikely to be cost-effective.

Impact of simplified HCV diagnostic strategies on the HCV epidemic among men who have sex with men in the era of HIV oral pre-exposure prophylaxis in Taiwan: a modelling study.

INTRODUCTION: Simplified hepatitis C virus (HCV) diagnostic strategies have the potential to improve HCV diagnoses and treatment. We aimed to investigate the impact of simplified HCV diagnostic strategies on HCV incidence and its effect on HCV diagnosis and treatment among men who have sex with men (MSM) regardless of HIV status and use of HIV pre-exposure prophylaxis (PrEP) in Taiwan. METHODS: A compartmental deterministic model was developed to describe the natural history of HCV disease progression, the HCV care cascade and the HIV status and PrEP using among MSM. The model was calibrated to available data for HCV and HIV epidemiology and population demographics in Taiwan. We simulated the epidemic from 2004 and projected the impact of simplified testing strategies on the HCV epidemic among MSM over 2022-2030. RESULTS: Under the current testing approach in Taiwan, total HCV incidence would increase to 12.6 per 1000 person-years among MSM by 2030. Single-visit point-of-care RNA testing had the largest impact on reducing the number of new HCV infections over 2022-2030, with a 31.1% reduction (interquartile range: 24.9%-32.8%). By 2030, single-visit point-of-care HCV testing improved HCV diagnosis to 90.9%, HCV treatment to 87.7% and HCV cure to 81.5% among MSM living with HCV. Compared to status quo, prioritized simplified HCV testing for PrEP users and MSM living with diagnosed HIV had considerable impact on the broader HCV epidemic among MSM. A sensitivity analysis suggests that reinfection risk would have a large impact on the effectiveness of each point-of-care testing scenario. CONCLUSIONS: Simplified HCV diagnostic strategies could control the ongoing HCV epidemic and improve HCV testing and treatment among Taiwanese MSM. Single-visit point-of-care RNA testing would result in large reductions in HCV incidence and prevalence among MSM. Efficient risk-reduction strategies will need to be implemented alongside point-of-care testing to achieve HCV elimination among MSM in Taiwan.

Preparing correctional settings for the next pandemic: a modeling study of COVID-19 outbreaks in two high-income countries.

Introduction: Correctional facilities are high-priority settings for coordinated public health responses to the COVID-19 pandemic. These facilities are at high risk of disease transmission due to close contacts between people in prison and with the wider community. People in prison are also vulnerable to severe disease given their high burden of co-morbidities. Methods: We developed a mathematical model to evaluate the effect of various public health interventions, including vaccination, on the mitigation of COVID-19 outbreaks, applying it to prisons in Australia and Canada. Results: We found that, in the absence of any intervention, an outbreak would occur and infect almost 100% of people in prison within 20 days of the index case. However, the rapid rollout of vaccines with other non-pharmaceutical interventions would almost eliminate the risk of an outbreak. Discussion: Our study highlights that high vaccination coverage is required for variants with high transmission probability to completely mitigate the outbreak risk in prisons.

Controlling COVID-19 outbreaks in the correctional setting: A mathematical modelling study.

Correctional centres (termed here 'prisons') are at high risk of COVID-19 and have featured major outbreaks worldwide. Inevitable close contacts, frequent inmate movements, and a disproportionate burden of co-morbidities mean these environments need to be prioritised in any public health response to respiratory pathogens such as COVID-19. We developed an individual-based SARS-CoV-2 transmission model for the prison system in New South Wales, Australia - incorporating all 33 correctional centres, 13,458 inmates, 578 healthcare and 6,909 custodial staff. Potential COVID-19 disease outbreaks were assessed under various mitigation strategies, including quarantine on entry, isolation of cases, rapid antigen testing of staff, as well as immunisation.Without control measures, the model projected a peak of 472 new infections daily by day 35 across the prison system, with all inmates infected by day 120. The most effective individual mitigation strategies were high immunisation coverage and prompt lockdown of centres with infected inmates which reduced outbreak size by 62-73%. Other than immunisation, the combination of quarantine of inmates at entry, isolation of proven or suspected cases, and widespread use of personal protective equipment by staff and inmates was the most effective strategy. High immunisation coverage mitigates the spread of COVID-19 within and between correctional settings but is insufficient alone. Maintaining quarantine and isolation, along with high immunisation levels, will allow correctional systems to function with a low risk of outbreaks. These results have informed public health policy for respiratory pathogens in Australian correctional systems.

Population movement can sustain STI prevalence in remote Australian indigenous communities.

BACKGROUND: For almost two decades, chlamydia and gonorrhoea diagnosis rates in remote Indigenous communities have been up to 30 times higher than for non-Indigenous Australians. The high levels of population movement known to occur between remote communities may contribute to these high rates. METHODS: We developed an individual-based computer simulation model to study the relationship between population movement and the persistence of gonorrhoea and chlamydia transmission within hypothetical remote communities. RESULTS: Results from our model suggest that short-term population movement can facilitate gonorrhoea and chlamydia persistence in small populations. By fixing the number of short-term travellers in accordance with census data, we found that these STIs can persist if at least 20% of individuals in the population seek additional partners while away from home and if the time away from home is less than 21 days. Periodic variations in travel patterns can contribute to increased sustainable levels of infection. Expanding existing STI testing and treatment programs to cater for short-term travellers is shown to be ineffective due to their short duration of stay. Testing and treatment strategies tailored to movement patterns, such as encouraging travellers to seek testing and treatment upon return from travel, will likely be more effective. CONCLUSION: High population mobility is likely to contribute to the high levels of STIs observed in remote Indigenous communities of Australia. More detailed data on mobility patterns and sexual behaviour of travellers will be invaluable for designing and assessing STI control programs in highly mobile communities.

The application of new metrics for understanding trends in undiagnosed HIV among key populations.

OBJECTIVE: Investigate the utility of novel metrics for understanding trends in undiagnosed HIV. METHODS: We produced estimates for the number of people with undiagnosed HIV and the number of new HIV infections using Australian surveillance data and the European Centre for Disease Prevention and Control HIV modelling tool. Using these estimates, we calculated: the total diagnosed fraction, the proportion of all people with HIV diagnosed; the yearly diagnosed fraction, the proportion of people who have not yet received a diagnosis who received a diagnosis during each year; and the case detection rate, which is the annual ratio of new HIV diagnoses to new HIV infections each year; from 2008 to 2019. We report trends in these metrics for Australian-born and overseas-born men who reported male-to-male sex and heterosexual women and men. RESULTS: Each metric for the Australian-born male-to-male sexual contact group improved consistently. In contrast, the metrics for the overseas-born group worsened (total diagnosed fraction: 85.0-81.9%, yearly diagnosed fraction: 23.1-17.8%, and case detection rate: 0.74-0.63). In heterosexuals, women and men had consistent increasing trends for the total diagnosed fraction and yearly diagnosed fraction but with women having consistently higher estimates. Heterosexual men had a declining case detection rate, falling to less than one in 2011, compared to an increase for women. CONCLUSIONS: The additional metrics provided important information on Australia's progress toward HIV elimination. The more dynamic changes in the undiagnosed population seen highlight diverging trends for key populations not seen in the total diagnosed fraction.

A population-level application of a method for estimating the timing of HIV acquisition among migrants to Australia.

INTRODUCTION: Australia has set the goal for the virtual elimination of HIV transmission by the end of 2022, yet accurate information is lacking on the level of HIV transmission occurring among residents. We developed a method for estimating the timing of HIV acquisition among migrants, relative to their arrival in Australia. We then applied this method to surveillance data from the Australian National HIV Registry with the aim of ascertaining the level of HIV transmission among migrants to Australia occurring before and after migration, and to inform appropriate local public health interventions. METHODS: We developed an algorithm incorporating CD4+ T-cell decline back-projection and enhanced variables (clinical presentation, past HIV testing history and clinician estimate of the place of HIV acquisition) and compared it to a standard algorithm which uses CD4+ T-cell back-projection only. We applied both algorithms to all new HIV diagnoses among migrants to estimate whether HIV infection occurred before or after arrival in Australia. RESULTS: Between 1 January 2016 and 31 December 2020, 1909 migrants were newly diagnosed with HIV in Australia, 85% were men, and the median age was 33 years. Using the enhanced algorithm, 932 (49%) were estimated to have acquired HIV after arrival in Australia, 629 (33%) before arrival (from overseas), 250 (13%) close to arrival and 98 (5%) were unable to be classified. Using the standard algorithm, 622 (33%) were estimated to have acquired HIV in Australia, 472 (25%) before arrival, 321 (17%) close to arrival and 494 (26%) were unable to be classified. CONCLUSIONS: Using our algorithm, close to half of migrants diagnosed with HIV were estimated to have acquired HIV after arrival in Australia, highlighting the need for tailored culturally appropriate testing and prevention programmes to limit HIV transmission and achieve elimination targets. Our method reduced the proportion of HIV cases unable to be classified and can be adopted in other countries with similar HIV surveillance protocols, to inform epidemiology and elimination efforts.

Optimizing point-of-care testing strategies for diagnosis and treatment of hepatitis C virus infection in Australia: a model-based cost-effectiveness analysis.

Background: Timely diagnosis and treatment of hepatitis C virus (HCV) is critical to achieve elimination goals. This study evaluated the cost-effectiveness of point-of-care testing strategies for HCV compared to laboratory-based testing in standard-of-care. Methods: Cost-effectiveness analyses were undertaken from the perspective of Australian Governments as funders by modelling point-of-care testing strategies compared to standard-of-care in needle and syringe programs, drug treatment clinics, and prisons. Point-of-care testing strategies included immediate point-of-care HCV RNA testing and combined point-of-care HCV antibody and reflex RNA testing for HCV antibody positive people (with and without consideration of previous treatment). Sensitivity analyses were performed to investigate the cost per treatment initiation with different testing strategies at different HCV antibody prevalence levels. Findings: The average costs per HCV treatment initiation by point-of-care testing, from A$890 to A$1406, were up to 35% lower compared to standard-of-care ranging from A$1248 to A$1632 depending on settings. The average costs per treatment initiation by point-of-care testing for three settings ranged from A$1080 to A$1406 for RNA, A$960-A$1310 for combined antibody/RNA without treatment history consideration, and A$890-A$1189 for combined antibody/RNA with treatment history consideration. When HCV antibody prevalence was <74%, combined point-of-care HCV antibody and point-of-care RNA testing were the most cost-effective strategies. Modest increases in treatment uptake by 8%-31% were required for immediate point-of-care HCV RNA testing to achieve equivalent cost per treatment initiation compared to standard-of-care. Interpretation: Point-of-care testing is more cost-effective than standard of care for populations at risk of HCV. Testing strategies combining point-of-care HCV antibody and RNA testing are likely to be cost-effective in most settings. Funding: National Health and Medical Research Council.