This study reports the proportion of MSM tested each year who are diagnosed with incident HIV infection at a public sexual health service in Melbourne, Australia from 2013 to 2017 and finds that a difference emerged between newly-arrived Asian-born and other MSM. The proportion tested each year diagnosed with incident HIV infection fell significantly in other MSM but not in newly-arrived Asian-born MSM. Our findings suggest that there was a change in risk factors for incident HIV infection among MSM in Melbourne over the study period. In the beginning of the study period there was no statistically significant difference between the two groups, but by the end of the study period newly-arrived Asian-born MSM were more than four times more likely to be diagnosed with incident HIV infection (1.56% vs 0.38%, p < .001). The disappearance of condom use and number of partners in later years as a risk factor for incident HIV suggests that limited access to biomedical interventions in newly-arrived Asian-born MSM is explaining the observed disparity in HIV incidence.
A recently published study of HIV testing in MSM in inner London reports a declining proportion of positive tests from late 2015 to late 2017 which they attribute to early diagnosis, early initiation of treatment and uptake of PrEP, that is biomedical rather than behavioural prevention . Melbourne is a so-called fast-track city and reports progress in excess of 90–90-90 targets [11, 12].
The probability of acquisition of HIV infection is related to the frequency of exposure, the per-exposure probability of transmission and the prevalence of unsuppressed HIV infection in sexual partners. We examined incident HIV infection of less than 1 year duration and therefore assume that the majority of HIV infections included in this study were locally acquired. In this study, newly-arrived Asian-born MSM report less sexual partners and more consistent condom use than other MSM who experienced a falling rate of diagnosis of incident HIV infection despite falling condom use. This suggests a change in vulnerability to HIV infection despite sexual behavior as measured on these indices. Although newly-arrived Asian-born MSM were less likely to report taking PrEP than others, the magnitude of the difference and the overall proportion taking PrEP (6.8% vs 11,1% in 2017 p < .001) would not suggest that PrEP use is an explanation for the four-fold difference in incident HIV diagnoses.
Available evidence points toward a substantial decline in the prevalence of unsuppressed HIV infection in Melbourne over the study period. With earlier diagnosis and initiation of antiretroviral therapy, the infectious period between infection and virological suppression has fallen more than five-fold . The magnitude and the timing of these changes could certainly explain the reduction in incident HIV infection in MSM in Melbourne.
Assortative sexual mixing patterns are of increasing interest in HIV transmission research . Our findings could, at least in part, be explained if newly-arrived Asian-born MSM were more likely to have newly-arrived Asian-born MSM as sexual partners and had a higher prevalence of unsuppressed HIV infection. Newly-arrived Asian-born MSM who are overseas students, working holiday makers or temporary migrants will not be eligible for Medicare or publicly funded ART. There is evidence to suggest that individuals born overseas may be less likely to be offered or less likely to initiate early antiretroviral therapy [26, 27]. At our centre, MSM couples have been studied in STI transmission studies . Of MSM couples studied at MSHC, 10 of 42 (24%) newly-arrived Asian born MSM and 30 of 685 other MSM (4.4%) reported being in a relationship with a newly-arrived Asian-born MSM (EPF Chow personal communication: unpublished).
Once diagnosed with HIV infection at Melbourne Sexual Health Centre, patients who are ineligible for Medicare are able to access medical services free of charge including antiretroviral therapy, which is provided through private compassionate access programs supported by the pharmaceutical industry. A recent analysis at this centre showed that country of birth and recent arrival in Australia were not associated with delayed HIV diagnosis or virological suppression after diagnosis . However, this centre is the only publicly funded sexual health centre that is able to offer these services free of charge in a city with a population of approximately five million people and with a large but unknown number of newly-arrived Asian born MSM. Therefore, it is possible that most newly-arrived Asian-born MSM who are infected with HIV are not patients of MSHC. Newly-arrived Asian-born MSM who are not engaged in care at a publicly funded sexual health centre (that provides sexual health and HIV medicine services free of charge) may be more likely to experience a delayed diagnosis or virological suppression after diagnosis.
In fact, delayed HIV diagnosis and virological suppression in newly-arrived Asian-born MSM who are not engaged in care at publicly funded sexual health centres may explain the difference in risk of HIV acquisition observed in this study. The prevalence of undiagnosed and untreated HIV infection (where HIV transmission to others may occur) may be higher in this group than in those with better health care access. Because of sexual mixing patterns, newly-arrived Asian-born MSM may be more likely to have sexual partners who are their peers, that is with peers with are able to transmit HIV infection to others. Sexual mixing patterns and restricted access to HIV testing, HIV treatment and PrEP may explain the large difference in proportion who are diagnosed with incident HIV infection that was observed in this study.
Furthermore, little is known about newly-arrived Asian-born MSM as a population: the size of the population, their sexual behavior, their perception or knowledge of risk of sexually transmitted infections including HIV or how to reduce that risk, how differential health care access might affect outcomes in other areas of health. Rising epidemics of HIV in MSM communities in Asia are increasingly described, including in mainland China . It is not known to what extent these epidemics are connected to HIV transmission amongst newly-arrived Asian-born MSM in Australia.
In this study, we have focused on health care access issues due to their pertinence to biomedical HIV prevention. However, additional research is required to identify and target other vulnerabilities that may place this group at increased risk, which may include language, culture, gay community engagement, sources of HIV information, sexual experience and ability to negotiate successful risk reduction strategies.
Our study is subject to certain limitations. Firstly, the primary outcome measure of our study, the proportion tested each year who are diagnosed with incident HIV infection, is not a direct measure of incidence and may underestimate it. However, the short testing intervals in the study population would suggest that in this population of MSM undergoing frequent retesting that this measure is closely linked to incidence and that there would not be a larger underestimation in other MSM than the newly-arrived Asian born MSM. The large difference in the outcome measure and the small difference in testing frequency between the groups means that a difference in HIV incidence is most probable reason for the observed difference. Secondly, MSM attending MSHC may not be representative of MSM in Victoria. Because patients who are ineligible for Medicare are able to access care free of charge, we would expect newly-arrived Asian-born MSM to be over-represented amongst MSHC patients, making it a useful site for study of this group. Also, because of ease of access at this site, it may be MSM attending MSHC have more frequent HIV testing.
In the era of biomedical HIV prevention, to maximize the success of these costly interventions at the population level, obstacles and barriers to access must be minimized. In Australia, with a highly accessibly universal health care system we have observed that while incident HIV is declining in most MSM, a subpopulation with less access to health care is still experiencing high incidence. Based on this, it is recommended that provision of sexual health and HIV medicine services free of charge, including HIV testing, antiretroviral therapy and preexposure prophylaxis is expanded to cover patients who are not eligible for Medicare. Preventable HIV infections are serious in any subpopulation, but many newly arrived Asian-born MSM will eventually return to countries with poorer protection and services for people living with HIV and may experience stigma, discrimination and poorer health outcomes.
Such intervention would come with considerable costs given that these services are not subsidised by Medicare. However, having a certain subpopulation with higher rates of HIV transmission and lower rates of testing and treatment will undermine the population effect of biomedical HIV prevention and reduce the return-on-investment for treatment as prevention and pre-exposure prophylaxis. This core group of undiagnosed infections will allow HIV to be sustained in the population as they are responsible for a disproportionate amount of transmissions. Hence the benefit of providing services to this group may outweigh the costs.
International students bring more than $20 billion into Australia each year and represent a larger source of foreign income than mining exports . Temporary migrants and international students make up a significant proportion of the population of young sexually active adults and withholding the benefits for accessing PrEP and TasP from them may be an Achilles’ heel of the biomedical prevention approach.