A modeling study of the Danish HIV epidemic in men who have sex with men: travel, pre-exposure prophylaxis and elimination

Awareness and willingness to utilize HIV pre-exposure prophylaxis and associated factors among men who have sex with men in Maanshan, China

OBJECTIVE

Men who have sex with men (MSM) are disproportionately affected by HIV and represent the primary target population for pre-exposure prophylaxis (PrEP) use. However, PrEP adoption in China remains limited, partly due to its late regulatory approval. This study aims to investigate the awareness and willingness of PrEP use and associated factors among MSM in Maanshan city, so as to promote the popularization of PrEP.

METHODS

This cross-sectional study was conducted in Maanshan City, China, between June 2016 and December 2019. Participants completed the questionnaire through respondent-driven sampling (RDS). The questionnaire information was organized and analyzed using SPSS 23.0 software. Both univariate and multivariate logistic regression models were employed to investigate the determinants of PrEP willingness and awareness among HIV-negative MSM.

RESULTS

A total of 879 participants were enrolled, with 837 providing analyzable data. The majority (62.25%) were aged <30 years old, with 97.49% self-identified as homosexual. Among participants, 50.18% reported regular male sexual partners. Regarding sexual behaviors, 71.80% of MSM engaged in casual sex and 36.56% unprotected anal sex (UAI) within the last six months. HIV awareness was reported by 92.83% of respondents, while PrEP awareness was substantially lower (22.70%). Willingness to use PrEP was high (89.49%), with 16.49% preferring to take PrEP daily and 84.59% preferring to take PrEP on demand. Multivariate logistic regression revealed that vocational school (vs. high school or below), recent casual sex engagement, PrEP awareness, and recent UAI history were significant predictors of PrEP willingness. Higher education (university or above vs. high school or below), versatile sexual role (vs. op/insertive ones), recent casual sex and prior HIV testing were positively associated with PrEP awareness.

CONCLUSIONS

Maanshan's MSM population demonstrated high PrEP acceptance but limited awareness. The findings suggest that expanding access to HIV testing could enhance PrEP awareness. Simultaneously, PrEP dissemination combined with targeted HIV prevention may effectively reduce HIV transmission in the MSM population.

Model-based evaluation of the impact of a potential HIV cure on HIV transmission dynamics

The development of an HIV cure is a global health priority, with the target product profile (TPP) for an HIV cure guiding research efforts. Using a mathematical model calibrated to data from men who have sex with men (MSM) in the Netherlands, we assessed whether an effective cure could help end the HIV epidemic. Following the TPP, we evaluated two scenarios: (i) HIV remission, where the virus is suppressed in an individual without ongoing antiretroviral therapy (ART) but may rebound, and (ii) HIV eradication, which aims to completely remove the virus from the individual. Here, we show that sustained HIV remission (without rebound) or HIV eradication could reduce new HIV infections compared to a scenario without a cure. In contrast, transient HIV remission with a risk of rebound could increase new infections if rebounds are not closely monitored, potentially undermining HIV control efforts. Our findings emphasize the critical role of cure characteristics in maximizing cure benefits for public health and highlight the need to align HIV cure research with public health objectives to end the HIV epidemic.

A modeling study of pre-exposure prophylaxis to eliminate HIV in Taiwan by 2030

BACKGROUND

The necessity of pre-exposure prophylaxis (PrEP) for ending the global AIDS epidemic by 2030 remains controversial. In Taiwan, the HIV epidemic predominantly affects young, sexually active men who have sex with men (MSM). This study aimed to model the impact and cost-effectiveness of a high-coverage oral emtricitabine/tenofovir PrEP program in Taiwan from an HIV elimination perspective.

METHODS

We applied stochastic and risk/age-structured deterministic modeling to assess the impact of PrEP scale-up on the basic reproduction number (R0) and the trajectory of the HIV epidemic in Taiwan, respectively. Both models were parameterized using the national HIV registry and cascade data. Cost-effectiveness was evaluated from a societal perspective.

RESULTS

Here we show that an intensive HIV test-and-treat strategy targeting HIV-positive individuals alone would substantially decrease HIV transmission but is not sufficient to eliminate the HIV epidemic among MSM at the estimated mixing level. In contrast, a PrEP program covering 50% of young, sexually active, high-risk, HIV-negative MSM would suppress HIV's R0 below 1, facilitating its elimination. It would also reduce HIV incidence to levels below the World Health Organization's HIV elimination threshold (1/1000 person-years) by 2030 and is highly cost-saving, yielding a benefit-cost ratio of 7.16. The program's effectiveness and cost-effectiveness remain robust even under conditions of risk compensation (i.e., no condom use among PrEP users), imperfect adherence (75%), or low-level emtricitabine/tenofovir resistance (1%).

CONCLUSION

Our findings strongly support scaling up PrEP for young, sexually active, high-risk, HIV-negative MSM as a critical strategy to end the HIV epidemic in Taiwan and globally.

Impact of increased diagnosis of early HIV infection and immediate antiretroviral treatment initiation on HIV transmission among men who have sex with men in the Netherlands

The number of new HIV infections among men who have sex with men (MSM) in the Netherlands has been decreasing, but additional efforts are required to bring it further down. This study aims to assess the impact of increased diagnosis of early HIV infection combined with immediate antiretroviral treatment (ART) initiation on reducing HIV transmission among MSM. We developed an agent-based model calibrated to HIV surveillance and sexual behavior data for MSM in the Netherlands in 2017-2022. Starting in 2023, we simulated a 10-year intervention that accelerates HIV diagnosis during the first 3 or 6 months after HIV acquisition across five levels of increased diagnosis rates (2, 4, 8, 16, and 32-fold), followed by immediate ART initiation. The upper limit of the intervention's impact over 10 years is projected to result in the cumulative 298 (95-th QI: 162-451) HIV infections averted. A 32-fold increase in the diagnosis rate within 3 months after HIV acquisition (corresponding to 100% of all new HIV infections diagnosed within 3 months of acquisition) results in 269 (95-th QI: 147-400) infections averted, approaching closely maximum impact. By extending the scope of the intervention to individuals who acquired HIV infection within the previous 6 months, a smaller 8-fold increase in the diagnosis rate (corresponding to 97% of new HIV infections diagnosed within 6 months of acquisition) approaches closely the maximum impact of the intervention by averting 256 (95-th QI: 122-411) HIV infections. Our sensitivity analyses showed that, in an epidemiological context similar to the modern-day the Netherlands, immediate initiation of ART accompanying accelerated diagnosis of individuals with early HIV infection does not significantly affect HIV transmission dynamics. Accelerating early HIV diagnosis through increased awareness, screening, and testing can further reduce transmission among MSM. Meeting this goal necessitates a stakeholder needs assessment.

Pre-exposure prophylaxis against HIV infection

Pre-exposure prophylaxis (PrEP) decreases the risk for HIV transmission in high-risk populations. PrEP has been available in Denmark since 2019 and consists of antiretroviral drugs in a combination tablet taken daily or on demand. The effect of this prophylaxis in Denmark is summarized in the review. PrEP is indicated in men and transgender persons with unprotected anal intercourse with multiple male partners in the latest 12 weeks or recent diagnoses of syphilis, chlamydia, or gonorrhoea. PrEP is provided by infectious disease specialists. Continued implementation could significantly reduce HIV transmission and potentially end the epidemic in Denmark.

Benefits and harms of cervical screening, triage and treatment strategies in women living with HIV

To support a strategy to eliminate cervical cancer as a public health problem, the World Health Organisation (WHO) reviewed its guidelines for screening and treatment of cervical pre-cancerous lesions in 2021. Women living with HIV have 6-times the risk of cervical cancer compared to women in the general population, and we harnessed a model platform ('Policy1-Cervix-HIV') to evaluate the benefits and harms of a range of screening strategies for women living with HIV in Tanzania, a country with endemic HIV. Assuming 70% coverage, we found that 3-yearly primary HPV screening without triage would reduce age-standardised cervical cancer mortality rates by 72%, with a number needed to treat (NNT) of 38.7, to prevent a cervical cancer death. Triaging HPV positive women before treatment resulted in minimal loss of effectiveness and had more favorable NNTs (19.7-33.0). Screening using visual inspection with acetic acid (VIA) or cytology was less effective than primary HPV and, in the case of VIA, generated a far higher NNT of 107.5. These findings support the WHO 2021 recommendation that women living with HIV are screened with primary HPV testing in a screen-triage-and-treat approach starting at 25 years, with regular screening every 3-5 years.

The Application of Systems Thinking to the Prevention and Control of Sexually Transmissible Infections among Adolescents and Adults: A Scoping Review

Systems thinking is a mechanism for making sense of complex systems that challenge linear explanations of cause-and-effect. While the prevention and control of sexually transmissible infections (STIs) has been identified as an area that may benefit from systems-level analyses, no review on the subject currently exists. The aim of this study is to conduct a scoping review to identify literature in which systems thinking has been applied to the prevention and control of STIs among adolescent and adult populations. Joanna Briggs Institute guidelines for the conduct of scoping reviews were followed. Five databases were searched for English-language studies published after 2011. A total of n = 6102 studies were screened against inclusion criteria and n = 70 were included in the review. The majority of studies (n = 34) were conducted in African nations. Few studies focused on priority sub-populations, and 93% were focused on HIV (n = 65). The most commonly applied systems thinking method was system dynamics modelling (n = 28). The review highlights areas for future research, including the need for more STI systems thinking studies focused on: (1) migrant and Indigenous populations; (2) conditions such as syphilis; and (3) innovations such as pre-exposure prophylaxis and at-home testing for HIV. The need for conceptual clarity around 'systems thinking' is also highlighted.

Impact and cost-effectiveness of non-governmental organizations on the HIV epidemic in Ukraine among MSM

OBJECTIVE

Non-governmental organizations (NGOs) in Ukraine have provided HIV testing, treatment, and condom distribution for MSM. HIV prevalence among MSM in Ukraine is 5.6%. We estimated the impact and cost-effectiveness of MSM-targeted NGO activities in Ukraine.

DESIGN

A mathematical model of HIV transmission among MSM was calibrated to data from Ukraine (2011-2018).

METHODS

The model, designed before the 2022 Russian invasion of Ukraine, evaluated the impact of 2018 status quo coverage levels of 28% of MSM being NGO clients over 2016-2020 and 2021-2030 compared with no NGO activities over these time periods. Impact was measured in HIV incidence and infections averted. We compared the costs and disability adjusted life years (DALYs) for the status quo and a counterfactual scenario (no NGOs 2016-2020, but with NGOs thereafter) until 2030 to estimate the mean incremental cost-effectiveness ratio (cost per DALY averted).

RESULTS

Without NGO activity over 2016-2020, the HIV incidence in 2021 would have been 44% (95% credibility interval: 36-59%) higher than with status quo levels of NGO activity, with 25% (21-30%) more incident infections occurring over 2016-2020. Continuing with status quo NGO coverage levels will decrease HIV incidence by 41% over 2021-2030, whereas it will increase by 79% (60-120%) with no NGOs over this period and 37% (30-51%) more HIV infections will occur. Compared with if NGO activities had ceased over 2016-2020 (but continued thereafter), the status quo scenario averts 14 918 DALYs over 2016-2030 with a mean incremental cost-effectiveness ratio of US$600.15 per DALY averted.

CONCLUSION

MSM-targeted NGOs in Ukraine have prevented considerable HIV infections and are highly cost-effective compared with a willingness-to-pay threshold of 50% of Ukraine's 2018 GDP (US$1548).

Can HIV epidemics among MSM be eliminated through participation in preexposure prophylaxis rollouts?

OBJECTIVE

To study the conditions under which preexposure prophylaxis (PrEP) coverage can eliminate HIV among MSM in the Paris region.

DESIGN

Mathematical modeling.

METHODS

We propose an innovative approach, combining a transmission model with a game-theoretic model, for decision-making about PrEP use. Individuals at high risk of HIV infection decide to use PrEP, depending on their perceived risk of infection and the relative cost of using PrEP versus antiretroviral treatment (ART), which includes monetary and/or nonmonetary aspects, such as price and access model of PrEP, consequences of being infected and lifelong ART.

RESULTS

If individuals assessed correctly their infection risk, and the cost of using PrEP were sufficiently low, then the PrEP rollout could lead to elimination. Specifically, assuming 86% PrEP effectiveness, as observed in two clinical trials, a minimum PrEP coverage of 55% [95% confidence interval (CI) 43-64%] among high-risk MSM would achieve elimination in the Paris region. A complete condom drop by MSM using PrEP slightly increases the minimum PrEP coverage required for elimination, by ∼1%, whereas underestimation of their own HIV infection risk would require PrEP programs reduce the cost of using PrEP by a factor ∼2 to achieve elimination.

CONCLUSION

Elimination conditions are not yet met in the Paris region, where at most 47% of high-risk MSM were using PrEP as of mid-2019. Further lowering the cost of PrEP and promoting a fair perception of HIV risk are required and should be maintained in the long-run, to maintain elimination status.

Can the combination of TasP and PrEP eliminate HIV among MSM in British Columbia, Canada?

INTRODUCTION

In British Columbia (BC), the HIV epidemic continues to disproportionally affect the gay, bisexual and other men who have sex with men (MSM). In this study, we aimed to evaluate how Treatment as Prevention (TasP) and pre-exposure prophylaxis (PrEP), if used in combination, could lead to HIV elimination in BC among MSM.

METHODS

Considering the heterogeneity in HIV transmission risk, we developed a compartmental model stratified by age and risk-taking behaviour for the HIV epidemic among MSM in BC, informed by clinical, behavioural and epidemiological data. Key outcome measures included the World Health Organization (WHO) threshold for disease elimination as a public health concern and the effective reproduction number (R_e). Model interventions focused on the optimization of different TasP and PrEP components. Sensitivity analysis was done to evaluate the impact of sexual mixing patterns, PrEP effectiveness and increasing risk-taking behaviour.

RESULTS

The incidence rate was estimated to be 1.2 (0.9-1.9) per 1000 susceptible MSM under the Status Quo scenario by the end of 2029. Optimizing all aspects of TasP and the simultaneous provision of PrEP to high-risk MSM resulted in an HIV incidence rate as low as 0.4 (0.3-0.6) per 1000 susceptible MSM, and an R_e as low as 0.7 (0.6-0.9), indicating that disease elimination was possible when TasP and PrEP were combined. Provision of PrEP to younger MSM or high-risk and younger MSM resulted in a similar HIV incidence rate, but an R_e with credible intervals that crossed one.

CONCLUSION

Further optimizing all aspects of TasP and prioritizing PrEP to high-risk MSM can achieve the goal of disease elimination in BC. These results should inform public health policy development and intervention programs that address the HIV epidemic in BC and in other similar settings where MSM are disproportionately affected.

The past, present and future impact of HIV prevention and control on HPV and cervical disease in Tanzania: A modelling study

Background

Women with HIV have an elevated risk of HPV infection, and eventually, cervical cancer. Tanzania has a high burden of both HIV and cervical cancer, with an HIV prevalence of 5.5% in women in 2018, and a cervical cancer incidence rate among the highest globally, at 59.1 per 100,000 per year, and an estimated 9,772 cervical cancers diagnosed in 2018. We aimed to quantify the impact that interventions intended to control HIV have had and will have on cervical cancer in Tanzania over a period from 1995 to 2070.

Methods

A deterministic transmission-dynamic compartment model of HIV and HPV infection and natural history was used to simulate the impact of voluntary medical male circumcision (VMMC), anti-retroviral therapy (ART), and targeted pre-exposure prophylaxis (PrEP) on cervical cancer incidence and mortality from 1995–2070.

Findings

We estimate that VMMC has prevented 2,843 cervical cancer cases and 1,039 cervical cancer deaths from 1995–2020; by 2070 we predict that VMMC will have lowered cervical cancer incidence and mortality rates by 28% (55.11 cases per 100,000 women in 2070 without VMMC, compared to 39.93 with VMMC only) and 26% (37.31 deaths per 100,000 women in 2070 without VMMC compared to 27.72 with VMMC), respectively. We predict that ART will temporarily increase cervical cancer diagnoses and deaths, due to the removal of HIV death as a competing risk, but will ultimately further lower cervical cancer incidence and mortality rates by 7% (to 37.31 cases per 100,000 women in 2070) and 5% (to 26.44 deaths per 100,000 women in 2070), respectively, relative to a scenario with VMMC but no ART. A combination of ART and targeted PrEP use is anticipated to lower cervical cancer incidence and mortality rates to 35.82 and 25.35 cases and deaths, respectively, per 100,000 women in 2070.

Conclusions

HIV treatment and control measures in Tanzania will result in long-term reductions in cervical cancer incidence and mortality. Although, in the near term, the life-extending capability of ART will result in a temporary increase in cervical cancer rates, continued efforts towards HIV prevention will reduce cervical cancer incidence and mortality over the longer term. These findings are critical background to understanding the longer-term impact of achieving cervical cancer elimination targets in Tanzania.

The Impact of Human Mobility on Regional and Global Efforts to Control HIV Transmission

HIV prevention and control methods are implemented on different scales to reduce the spread of the virus amongst populations. However, despite such efforts, HIV continues to persist in populations with a global incidence rate of 1.8 million in 2017 alone. The introduction of new infections into susceptible regional populations promotes the spread of HIV, indicating a crucial need to study the impact of migration and mobility on regional and global efforts to prevent HIV transmission. Here we reviewed studies that assess the impact of human mobility on HIV transmission and spread. We found an important role for both travel and migration in driving the spread of HIV across regional and national borders. Combined, our results indicate that even in the presence of control and preventive efforts, if migration and travel are occurring, public health efforts will need to remain persistent to ensure that new infections do not grow into outbreaks.