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The HIV care continuum in black MSM in the USA - Commentary
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Download the PDF here
Download the PDF here
........"Viral suppression, the penultimate desired effect on the continuum, is achieved in 16% of black and 34% of white MSM.......The inclusion of all MSM living with HIV infection in this analysis (and not only those who have been diagnosed) led to substantially different estimates of the HIV care continuum from those in federal reports. For example, Singh and colleagues9 reported in September, 2014, that 46% of black MSM are retained in care, whereas Rosenberg and colleagues found only 24% are.1 Likewise, Whiteside and colleagues10 reported 37% of black MSM were virally suppressed, whereas Rosenberg and colleagues found only 16%.....High rates of poverty, incarceration, unemployment, and low education are driven by historical and current policies that disproportionally affect black people in the USA"...............Because disparities in the HIV care continuum likely account for most of the disparities in HIV transmission rates between black and white MSM, there is an urgent need to improve our rates of HIV testing, linkage and retention in care, and prescription of and adherence to antiretroviral therapy for black MSM living with HIV....... the transmission rate ratio should be used as a proximate indicator of the success of programmes designed to reduce disparities in HIV between black and white MSM. In terms of policy, our results draw attention to the importance of the 2013 presidential executive order focusing on the HIV care continuum and the National HIV/AIDS Strategy's prioritisation of reducing HIV-related health disparities.21 Also, our data show the urgent need for research towards a cure or a highly effective HIV vaccine, or both. In the absence of such transformational biomedical advances in HIV prevention, disparities by race in HIV incidence rate in MSM are likely to persist in the US epidemic in the foreseeable future."
The Lancet HIV Nov 18 2014
Tonia Poteat, Jordan White, *Frits van Griensven
Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA (TP, JW); Thai Red Cross AIDS Research Center, Bangkok, Thailand (FvG), and Division of Preventive Medicine and Public Health, University of California, San Francisco, CA, USA
In The Lancet HIV, Eli Rosenberg and colleagues1 report their reconstruction and population of the HIV care continuum from publicly available and nationally representative data of men who have sex with men (MSM) in the USA. Viral suppression, the penultimate desired effect on the continuum, is achieved in 16% of black and 34% of white MSM. After modelling various scenarios of how differences in viral suppression could affect the future course of the epidemic, the investigators reach the disappointing conclusion that even in the best-case scenario racial disparities in HIV prevalence will sustain a higher incidence in black MSM for decades to come.
These disheartening conclusions show the long-term consequences of historical neglect. Immediately after the first epidemiological investigations of HIV infection in MSM in the USA started in 1984, Samuel and Winkelstein2 not only reported racial disparities in HIV seroprevalence and incidence, but also that, contrary to their expectation, these disparities could not be accounted for by race-associated differences in HIV risk behaviour.
Similarly, after all US states and territories had implemented AIDS case reporting in 1986, Bakeman and colleagues3, 4, 5 analysed and reported the AIDS Public Information Data Set from US Centers for Disease Control and Prevention (analogous to the rationale and approach used by Rosenberg1 to obtain and report the data presented in the current study) demanding interventions to stop the emerging and widening HIV/AIDS epidemic in black Americans.
The racial disparity findings in HIV/AIDS have been repeatedly corroborated in HIV case reporting, surveillance, and research. However, the first US federally funded evidence-based HIV prevention intervention designed specifically for black MSM was not published6 until 2009-a quarter of a century after racial disparities in HIV infection were first noted between black and white MSM.2
The increased federal investment in HIV prevention in black MSM is promising. However, the focus on HIV testing and biomedical interventions is unlikely to have the effect needed to end disparities in care. Black MSM are already as likely as or more likely than are white MSM to use condoms, to get tested for HIV, and even to use pre-exposure chemoprophylaxis.7 However, these preventive behaviours have not reduced racial disparities along the care continuum, nor have they reversed the increasing trend in HIV incidence. Indeed, Rosenberg and colleagues note that the same structural barriers affecting the HIV care continuum are likely to affect access to and use of any other biomedical HIV prevention measure.
The researchers leave us with the dire prediction that short of "transformational biomedical advances", such as an effective HIV vaccine or a cure, racial disparities in MSM will persist for the foreseeable future. While we wait for scientific process to take its course in delivering biomedical advances, the structural interventions and changes needed to facilitate affordable, effective, and unrestricted access to the new preventive methods can be started today.8
Positive structural changes in the organisation of the health-care system of the USA will help to improve overall access to quality health care in the country. However, this might not benefit black Americans generally. Black MSM have lower rates of health insurance than do white MSM, starting with reduced access to health-care services. The Affordable Care Act has increased access to care for people who live in states that have elected to expand Medicaid. However, most states in southern USA (where most black Americans with HIV live) have rejected Medicaid expansion. A mandatory Medicaid expansion would likely increase health-care access for many black MSM who live in the south. However, even when such access would become available, structural interventions and change will still be needed to provide unrestricted and unhindered access to this expansion.
High rates of poverty, incarceration, unemployment, and low education are driven by historical and current policies that disproportionally affect black people in the USA. These policies can be changed in ways that improve life circumstances that put black MSM at higher risk for HIV. For example, elimination of policies such as stop and frisk that target young black men would serve to reduce the number of black men in the criminal justice system, allowing them to spend more time on education, expanding employment opportunities, and reducing exposure to HIV in prison.
The inclusion of all MSM living with HIV infection in this analysis (and not only those who have been diagnosed) led to substantially different estimates of the HIV care continuum from those in federal reports. For example, Singh and colleagues9 reported in September, 2014, that 46% of black MSM are retained in care, whereas Rosenberg and colleagues found only 24% are.1 Likewise, Whiteside and colleagues10 reported 37% of black MSM were virally suppressed, whereas Rosenberg and colleagues found only 16%.1 These differences show the need for consensus about the timing of initiation of the continuum. In view of the effect that undiagnosed HIV infected people have on the HIV epidemic, their inclusion in our understanding of transmission dynamics and appropriate interventions is crucial.
Both the methods and the findings of this study show that the USA cannot reduce new infections without addressing structural factors and attending to social justice. Data that provide road maps to begin addressing the structural issues that surround disparities in HIV prevention, care, and treatment in black and white MSM are becoming available. It might be wise to follow where they lead; however, since the roots of racial inequality and injustice in the USA run deep, much more depth and a much greater toolbox will be needed to uproot and eradicate causes definitively.
We declare no competing interests. Partial support for this work was received from the NIH (TP, JW). The funder had no involvement in the current report.
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Understanding the HIV disparities between black and white men who have sex with men in the USA using the HIV care continuum: a modeling study
The Lancet HIV Nov 18 2014
Eli S Rosenberg, Gregorio A Millett, Patrick S Sullivan, Carlos del Rio, James W Curran
Summary
Background
Disparities in HIV incidence and prevalence between black and white men who have sex with men (MSM) in the USA remain largely unexplained. We assessed the effect of interventions for black MSM that might reduce disparities in HIV care continuum and incidence in MSM.
Methods
Using data from the US Centers for Disease Control and Prevention (CDC), we constructed the HIV care continuum for black and white MSM for 2009-10. These data were used in a deterministic model to estimate race-specific transmissions, transmission rates, incidence rate, and rate ratios.
Findings
Disparities were noted throughout the care continuum, with 28 251 (16%) of 180 477 black MSM and 83 223 (34%) of 243 174 white MSM achieving viral suppression. An estimated 9833 and 9710 new HIV transmissions per year were attributable to HIV-positive black and white MSM, respectively (transmission rate ratio 1·36 and incidence rate ratio 7·92). In a model in which black and white MSM had identical care outcomes, the transmission rate ratio was 1·00 and incidence rate ratio was 5·80. In scenarios of 95% diagnosis, 95% retention, and concurrent 95% diagnosis and 95% retention, the transmission rate ratios were 1·00, 1·02, and 0·56, respectively, and incidence rate ratios were 5·81, 5·93, and 3·28, respectively.
Interpretation
Disparities in the rates of HIV transmission could be reduced by improving the outcomes of the HIV care continuum, but racial disparities in HIV prevalence are likely to continue sustaining the higher incidence in black MSM for decades to come.
Funding
US National Institutes of Health.
Introduction
In the USA, the incidence of HIV infection is rising among men who have sex with men (MSM), and as with many other illnesses important racial differences exist.1, 2, 3 Black MSM have had disproportionately higher incidence and prevalence of HIV infection since the start of the epidemic.4Although the factors that gave rise to disparities between black and white MSM in HIV infection are not completely understood, data are emerging to suggest that some factors are important for sustaining those disparities. Results of meta-analyses have shown that black MSM do not have more risk-associated behaviours than do white MSM.5 Possible hypotheses have been proposed that take into account the effects of social network structures and treatment disparities.6 Existing disparities in HIV prevalence and socioeconomic factors might also contribute to ongoing disparities.7, 8, 9 For example, because of higher HIV prevalence and lower rates of viral suppression in black MSM and substantial racial concordance in sexual partnerships, equivalent risk behaviours in black MSM confer a higher probability of exposure to an HIV-transmitting male partner than in white MSM.8 In a study of MSM in Atlanta, GA, USA, having black partners significantly accounted for the disparities in HIV incidence between black and white MSM.10 Other investigators have suggested that racial differences in clinical care outcomes in HIV-infected MSM exacerbate such disparities.11, 12
New HIV infections in a population are a function of behavioural and biological factors, including the number of serodiscordant sexual partnerships, number of unprotected sex acts, and viral load in infected partners.13 Within a serodiscordant partnership, the transfer of HIV might be seen from the perspective of the person acquiring or transmitting HIV.
According to reports, disparities exist between racial or ethnic groups in HIV prevalence (infection burden) or HIV incidence (new infections).10, 11, 14, 15Disparities in HIV transmission (ie, the extent to which HIV-infected black MSM are more likely to transmit infection than are HIV-infected white MSM) have been assessed in only a few studies.12, 16 The differences in the risk behaviours associated with HIV transmission in MSM by race have been assessed to help explain high infection rates in black MSM.17, 18 Following these studies, HIV transmission rates (average transmissions per person living with HIV) were calculated with HIV surveillance data for diagnosed and undiagnosed infection in a recent study, and although only a fifth of the men in the USA are black, there are about the same number of black and white MSM with HIV without viral suppression.19
The HIV care continuum has become an important model for the measurement of HIV/AIDS care in populations through nested steps of HIV infection, diagnosis, retention in care, prescription of antiretroviral therapy, and viral suppression.20, 21 A full HIV care continuum for MSM by race (ie, including those living with undiagnosed HIV infection) has not been constructed and the degree to which dropout from the continuum contributes to disparities in HIV infection has not been modelled. Using available national data sources, we assessed how existing disparities in HIV prevalence and in the HIV care continuum between races translate into and explain differences in incidence in MSM.
Methods
HIV care continuum
Using nationally representative data from the US Centers for Disease Control and Prevention (CDC) for people with HIV in 2009 and 2010 in the USA (table 1), we estimated separate HIV care continuums for black and white MSM.1, 12, 19 When more than one set of estimates were available, we selected those with greater subpopulation details.
Population sizes along the care continuum were represented in three ways. The first was the typical cumulative prevalence method in which population size decreases monotonically from HIV infection to viral suppression.20, 22 The second was the percentage of the population who attained a particular step of care, conditional on attaining the previous step. Third, by subtraction, we obtained the number of individuals at three broader, mutually exclusive stages of care; HIV-infected but undiagnosed, diagnosed but not virologically suppressed, and virologically suppressed. These stages are the most informative for understanding the relative contribution of individuals at each stage to ongoing transmission, and thus for the targeting of prevention efforts.
HIV transmission
We used published yearly per-person transmission rates from individuals with HIV in the USA in 2009 for those with undiagnosed infection (rate 0·108), diagnosed infection but not virally suppressed (0·046), and individuals virally suppressed (0).19, 24 An estimated 83% of MSM diagnosed but not virally suppressed are out of care.22 Stage-specific transmission rates, and thus transmission risk behaviours, were kept constant between black and white MSM, consistent with previous research for the comparison of sexual behaviours by race because of the unavailability of race-specific estimates.5, 11
Next, we estimated the number of HIV transmissions from black and white MSM with HIV infection at each step of care by multiplying the number of MSM of each race at each care step with the transmission rate for that step. Division by the race-specific number of MSM living with HIV provided the race-specific transmission rate, the ratio of which was an estimate of the transmission rate ratio or the disparity in HIV transmission.
HIV incidence
The total numbers of transmissions by race were used to imply incident infections (in different racial mixing scenarios), and these were compared with CDC back-calculation estimates of 2009 race-specific incident infection counts.2 Although national incidence rates are not published, we estimated these from other population-based sources. The number of MSM living in the USA was computed by use of 2008 estimates from a meta-analysis of population-based surveys with behavioural definitions of MSM, accounting for population growth in individuals aged 13 years and older from 2008 to 2010 (appendix).25, 26 Race-specific totals were calculated for the overall distribution of the races in the USA.25 Using the number of black and white MSM living with HIV, we next computed race-specific HIV prevalence, number of men living without HIV, and thus the incidence rate, and incidence rate ratio for the comparison of black versus white MSM.
Intervention scenarios
We used hypothetical interventions along the continuum of care for black MSM as both a sensitivity analysis and to understand the relative contributions of the steps of care and existing prevalence to transmission and incidence in black MSM.20 Using the known care continuum as a base case (observed continuum), we assessed HIV transmission rates, incidence, and rate ratios in counterfactual scenarios that began with the same number of black MSM with HIV infection, but altered coverage of subsequent steps in the care continuum by modifying the percentages of individuals attaining subsequent steps. These four scenarios were equivalent care achievement as white MSM (racially equivalent care), 95% diagnosis, 95% retention, or concurrent 95% diagnosis and 95% retention.
Race-mixing sensitivity analyses
For the primary analysis, we assumed all serodiscordant MSM partnerships were with same-race men. Results of previous studies have indicated greater racial mixing among MSM than among the heterosexual population, but mixing varies regionally and no nationally representative partnership race-mixing data are available for MSM.27 Furthermore, transmission analyses require race-mixing data for the specific subset of HIV-serodiscordant partnerships, ideally those in which transmission is likely to occur or has occurred. In sensitivity analyses, we reassessed all outcomes in different race-mixing scenarios. These included hypothetical scenarios and those based on data from 5978 partnerships with anal intercourse and 432 with serodiscordant anal intercourse from three sources: a national online study, and an Atlanta-based cohort, and an Atlanta-based sexual networks study (appendix).28, 29, 30 To account for all MSM transmissions in the population, a third group of Hispanic or other race MSM was included, with a care continuum approximated from the above sources.19, 22 The results are reported on an interactive spreadsheet.
Role of the funding source
The funding source had no role in data analysis or interpretation, writing of the report, or the decision to submit the report. The corresponding author had full access to all of the published data in the study and final responsibility for the decision to submit for publication.
Results
In 2010, about 562 500 black and 3 231 061 white adult MSM were living in the USA (figure 1). Of these, an estimated 180 477 black and 243 174 white MSM had HIV, giving prevalences of 32% and 8% respectively (Figure 1, Figure 2). Disparities were noted at all steps of the HIV care continuum, most notably in retention in care-33% of black and 51% of white MSM diagnosed with HIV infection were retained in care (figure 2). An estimated 16% of black and 34% of white MSM achieved HIV suppression (figure 2).
With application of per-person transmission rates to each care continuum, 9710 transmissions were attributable to white MSM and 9833 to black MSM (observed continuum; table 2), resulting in a transmission rate ratio of 1·36 (5·45 per 100 black MSM vs 3·99 per 100 white MSM) and an incidence rate ratio of 7·92 (2·57 per 100 black MSM vs 0·32 per 100 white MSM; table 2). The higher incidence rate ratio, as opposed to transmission rate ratio, was a result of the smaller total population of HIV-negative black MSM than the total population of HIV-negative white MSM and the larger proportion of prevalent HIV-positive black MSM (Figure 1, Figure 2).
In a scenario of racially equivalent care in which black MSM have the same care continuum as do white MSM, the HIV transmission rate ratio is defined as 1·00. The equalisation of transmission likelihood through the equality of care alone results in a 27% reduction in the estimated incidence rate and 27% reduction in the rate ratio in black MSM compared with scenario 1 (table 2). The remaining 73% of excess incidence was attributable to current disparities in prevalence of HIV infection.
At a constant care continuum for white MSM, the estimated transmission and incidence in the 95% diagnosis scenario for all black MSM were nearly identical to those in the racially equivalent care scenario (table 2). Similar to scenario 1, in the 95% retention scenario for black MSM, the estimated transmission rate ratio was 1·02 and incidence rate ratio was reduced by 25%. In the concurrent 95% diagnosis and 95% retention scenario, the estimated transmission rate ratio fell to 0·56 and the incidence rate ratio fell by 59%. In this scenario, however, the estimated incidence rate ratio remains increased at 3·28 because of the larger prevalent HIV-positive black MSM population, of whom 76 233 (42%) of 180 477 do not have suppression of the virus. The results were nearly identical with the same interventions at 100% coverage (data not shown).
In sensitivity analyses of different race-mixing configurations, estimates of the incidence rate ratio for black and white MSM in the observed continuum scenario varied from 7·89 to 9·22 (appendix). In all race-mixing scenarios, reductions achieved in the incidence of HIV infection in the black MSM population through improvements in diagnosis and care were attenuated because these changes partly reduced HIV transmission to other races, and were responsible for unmodified and continued transmission to black MSM.
Comparison of the estimates from the observed continuum scenario with those from other studies of US surveillance data in which independent methods were used enabled validation of the findings from the model. Predicted infection totals were similar to previously reported back-calculated incidence estimates of 10 800 for black MSM and 11 400 for white MSM (table 2).2
Discussion
According to our model, the disparity in HIV transmission rate between black and white men is substantially lower than the disparity in HIV incidence rates: the black-white transmission rate ratio in our model was 1·36, but the HIV incidence rate ratio was 7·92 as a result of differences in HIV prevalence, population size, and the tendency towards racially concordant relationships (table 2).
Our counterfactual scenarios show the challenges in addressing HIV disparities by race because of the existing differences in HIV prevalence. Even with the assumption that black MSM have a similar continuum to that for white MSM and a reduced transmission rate ratio of 1·0, black MSM will still have an estimated HIV incidence 5·8 times that of white MSM (table 2). The disparity in the estimates of HIV transmission was reduced, under the ideal (but challenging to achieve) scenario of concurrent 95% diagnosis and retention in care for black MSM, with a rate ratio of less than 1 for black MSM; the disparity in incidences was also greatly reduced although incidence was still three times higher (table 2). These findings suggest that, even if disparities in transmission rates are addressed, the higher HIV prevalence in black MSM will continue to compound disparities in HIV incidence for many years to come. Reversal of this trend will only be possible through a sustained reduction in the HIV transmission rate to less than 1 for a sufficient period to allow a reduction in the current number of prevalent HIV-positive black MSM and an increase in HIV-negative cohorts in successive generations.
By synthesising existing nationally representative CDC estimates, we show the role of differences in HIV care continuums in the perpetuation of disparities in HIV between black and white MSM. Our results extend existing work (panel) by presenting separate HIV care continuums for black and white MSM, including those with HIV irrespective of their diagnosis status. Our results suggest important lessons that could inform prevention priorities and prospects for mitigating these disparities in MSM in the USA, one of many health-related racial disparities.
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Panel
Research in context
Systematic review
We updated findings from a meta-analysis.11 Additional US care-continuum and transmission results for white men who have sex with men (MSM) were found through PubMed searches from Jan 1, 2012, to Aug 15, 2014, with the terms "HIV care continuum MSM" and "HIV transmission MSM United States", and by searching the HIV case surveillance report listing on the US Centers for Disease Control and Prevention website.
Interpretation
Large gaps exist in both existing infections and care continuum outcomes between black and white MSM, resulting in even larger racial disparities in HIV incidence. Even if extreme care interventions resulted in 2·3 transmissions per 100 black MSM who were HIV positive, compared with four transmissions per 100 white MSM who were HIV positive, disparities in HIV incidences will persist because of many more prevalent positives in the black MSM community.
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In the USA, one in three black MSM has HIV infection, compared with less than one in ten white MSM.25 The results for the race-specific HIV care continuum show consistent disparities for black and white MSM at each step of the continuum: black MSM are less likely to be diagnosed with HIV infection, to be retained in care, to be on antiretroviral therapy, and to achieve viral suppression. These disparities in the care continuum culminate in black MSM achieving less than half of the virological suppression achieved by white MSM. Previous analyses have presented partial care continuums for black MSM30 and for black and white MSM.31 These partial care continuums exclude men living with undiagnosed HIV infection; therefore these results are not directly comparable to our results, but also show lower viral suppression among black MSM. Also, the previous partial continuums estimated retention in care based on 19 US jurisdictions, whereas our analysis used published CDC methodology to estimate retention.21 These disparities were validated in a meta-analysis of studies for the comparison of black and white HIV-infected MSM,11 but the results of our analysis add to those findings by showing that disparate HIV transmission rates due to racial differences in care might help compound disparities in HIV incidence in the black MSM population.
The results of our analyses show the substantial challenges in reducing or eliminating disparities in HIV incidence between black and white people in the short term. The results also suggest that we must address all elements of the HIV care continuum for all MSM to achieve meaningful reductions in the disparities in HIV incidences and, crucially, to achieve the care and transmission outcomes despite low levels of viral suppression in all races. Increasing HIV testing as a sole approach to reducing racial disparities is likely to have a small effect. Even public health approaches that substantially address disparities in transmission rates for black MSM will not lead to similar reductions in HIV incidence. Therefore, importantly, additional approaches such as pre-exposure prophylaxis have to be applied at scale as part of a combination HIV prevention strategy for black MSM.32 Because adequate estimates of the protective effect of pre-exposure prophylaxis for black MSM have yet to be published, such interventions for HIV-uninfected black MSM are not included in our model of the HIV-infected population. Although pre-exposure prophylaxis has a great potential in reducing incidence, scale-up might be inhibited by the same social or structural barriers to care outcomes for black MSM with HIV.7
Our model and interpretations have important limitations. First, our input data were derived from different systems from both 2009 and 2010. However, our sources were nationally representative data systems. Second, our primary model was based on the assumption that serodiscordant partnerships were 100% same race. Accordingly, all changes to HIV care for a racial group and resulting transmissions were attributed to that group's incident infections. Thus, the reported estimates of changes in incidence were best-case scenarios. From sensitivity analyses of racial mixing in serodiscordant partnerships, we expect that prioritising black MSM who are HIV-positive for intervention might have less effect on the incidence of HIV infection in this population than our model suggests, but would benefit other racial groups. Also, our overall estimate of HIV incidence for MSM was lower than that reported in a meta-analysis of HIV epidemics in mainly urban regions of the USA, Europe, and Australia.33 Noteworthy is that previous HIV incidence rate estimates in MSM populations have been derived largely from men recruited in bars and similar venues associated with higher HIV acquisition risk, in urban areas, and represented mostly younger MSM, who tend to have higher HIV incidence rates than do older MSM. Furthermore, our estimates of HIV incidence are nearly identical to that derived from combining CDC's estimates of 2009 incident infections in MSM using independent methods. Also, our national estimate of HIV incidence rate improves on earlier work because we used incident infections, rather than diagnoses, in the numerator and adjusted the denominator of MSM at risk by subtracting the number of MSM living with HIV.25 Transmission rates used might not fully capture the incompletely understood role of acute infection in the epidemic in the MSM population, possible undocumented behavioural or circulating viral differences between HIV-positive black and white MSM, or differences in host susceptibility.34 Because some source data reports did not include estimates of random error, we could not include these for our model results.
Our study has clear programmatic and policy implications. Because disparities in the HIV care continuum likely account for most of the disparities in HIV transmission rates between black and white MSM, there is an urgent need to improve our rates of HIV testing, linkage and retention in care, and prescription of and adherence to antiretroviral therapy for black MSM living with HIV. Efficacious and cost-effective interventions are available to increase HIV testing, care engagement, and adherence to antiretroviral therapy, although more research is needed into tailored interventions and resource allocation for this population.35 Additionally, important socioeconomic disparities between white and black MSM need to be addressed because these might negatively affect the effectiveness of the interventions in the care continuum. Dynamic models are needed to assess the long-term outcomes of interventions for prevention that achieve parity in HIV transmission rates in black and white MSM. Furthermore, the transmission rate ratio should be used as a proximate indicator of the success of programmes designed to reduce disparities in HIV between black and white MSM. In terms of policy, our results draw attention to the importance of the 2013 presidential executive order focusing on the HIV care continuum and the National HIV/AIDS Strategy's prioritisation of reducing HIV-related health disparities.21 Also, our data show the urgent need for research towards a cure or a highly effective HIV vaccine, or both. In the absence of such transformational biomedical advances in HIV prevention, disparities by race in HIV incidence rate in MSM are likely to persist in the US epidemic in the foreseeable future.
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