Added Benefits of Pre-Exposure Prophylaxis Use on HIV Incidence with Minimal Changes in Efficiency in the Context of High Treatment Engagement Among Men Who Have Sex with Men

The relationship between age and sex partner counts during the mpox outbreak in the UK, 2022

BACKGROUND

Understanding the dynamics of an infectious disease outbreak linked to sexual activity requires valid expectations of likely counts of unique sex partners during the infectious period. Typically, age is the key demographic trait linked to expected partner count, with many transmission models removing adults from the sexually active pool abruptly at a pre-specified age threshold. Modelling the rate of decline in partner counts with age would benefit from a better description of empirical evidence.

METHODS

During the 2022 mpox epidemic in the UK, we asked individuals about their partner counts in the preceding three weeks, which is about the same as usual infectious period for persons with active mpox. We used negative binomial regression (all responses) and Weibull regression (non-zero responses) to analyse the relationship between age and partner counts, adjusted for other demographic data (such as education level and occupation), sub-dividing by three types of respondent: men who have sex with men (MSM), men who have sex with women, and women who have sex with men.

RESULTS

Most respondents had zero or one recent partner, all distributions were skewed. There was a relatively linear declining relationship between age and partner counts for heterosexual partnership groups, but a peak in partner counts and concurrency for MSMs in middle age years (age 35-54), especially for MSM who seemed to be in a highly sexually active subgroup.

CONCLUSION

Useful data were collected that can be used to describe sex partner counts during the British mpox epidemic and that show distinctive partner count relationships with age, dependent on partnership type.

Expanding Medicaid to Reduce Human Immunodeficiency Virus Transmission in Houston, Texas: Insights From a Modeling Study

CONTEXT

Medicaid expansion has been nationally shown to improve engagement in the human immunodeficiency virus (HIV) treatment and prevention continua, which are vital steps to stopping the HIV epidemic. New HIV infections in the United States are disproportionately concentrated among young Black men who have sex with men (YBMSM). Houston, TX, is the most populous city in the Southern United States with a racially/ethnically diverse population that is located in 1 of 11 US states that have not yet expanded Medicaid coverage as of 2021.

METHODS

An agent-based model that incorporated the sexual networks of YBMSM was used to simulate improved antiretroviral treatment and pre-exposure prophylaxis (PrEP) engagement through Medicaid expansion in Houston, TX. Analyses considered the HIV incidence (number of new infections and as a rate metric) among YBMSM over the next 10 years under Medicaid expansion as the primary outcome. Additional scenarios, involving viral suppression and PrEP uptake above the projected levels achieved under Medicaid expansion, were also simulated.

RESULTS

The baseline model projected an HIV incidence rate of 4.96 per 100 person years (py) and about 368 new annual HIV infections in the 10th year. Improved HIV treatment and prevention continua engagement under Medicaid expansion resulted in a 14.9% decline in the number of annual new HIV infections in the 10th year. Increasing viral suppression by an additional 15% and PrEP uptake by 30% resulted in a 44.0% decline in new HIV infections in the 10th year, and a 27.1% decline in cumulative infections across the 10 years of the simulated intervention.

FINDINGS

Simulation results indicate that Medicaid expansion has the potential to reduce HIV incidence among YBMSM in Houston. Achieving HIV elimination objectives, however, might require additional effective measures to increase antiretroviral treatment and PrEP uptake beyond the projected improvements under expanded Medicaid.

Population Impact and Efficiency of Improvements to HIV PrEP Under Conditions of High ART Coverage Among San Francisco Men Who Have Sex With Men

BACKGROUND

Key components of Ending the HIV Epidemic (EHE) plan include increasing HIV antiretroviral therapy (ART) and HIV pre-exposure prophylaxis (PrEP) coverage. One complication to addressing this service delivery challenge is the wide heterogeneity of HIV burden and health care access across the United States. It is unclear how the effectiveness and efficiency of expanded PrEP will depend on different baseline ART coverage.

METHODS

We used a network-based model of HIV transmission for men who have sex with men (MSM) in San Francisco. Model scenarios increased varying levels of PrEP coverage relative under current empirical levels of baseline ART coverage and 2 counterfactual levels. We assessed the effectiveness of PrEP with the cumulative percentage of infections averted (PIA) over the next decade and efficiency with the number of additional person-years needed to treat (NNT) by PrEP required to avert one HIV infection.

RESULTS

In our projections, only the highest levels of combined PrEP and ART coverage achieved the EHE goals. Increasing PrEP coverage up to 75% showed that PrEP effectiveness was higher at higher baseline ART coverage. Indeed, the PIA was 61% in the lowest baseline ART coverage population and 75% in the highest. The efficiency declined with increasing ART (NNT range from 41 to 113).

CONCLUSIONS

Improving both PrEP and ART coverage would have a synergistic impact on HIV prevention even in a high baseline coverage city such as San Francisco. Efforts should focus on narrowing the implementation gaps to achieve higher levels of PrEP retention and ART sustained viral suppression.

Attributing health benefits to preventing HIV infections versus improving health outcomes among people living with HIV: an analysis in six US cities

OBJECTIVE

Combination strategies generate health benefits through improved health outcomes among people living with HIV (PLHIV) and prevention of new infections. We aimed to determine health benefits attributable to improved health among PLHIV versus HIV prevention for a set of combination strategies in six US cities.

DESIGN

A dynamic HIV transmission model.

METHODS

Using a model calibrated for Atlanta, Baltimore, Los Angeles, Miami, New York City (NYC) and Seattle, we assessed the health benefits of city-specific optimal combinations of evidence-based interventions implemented at publicly documented levels and at ideal (90% coverage) scale-up (2020-2030 implementation, 20-year study period). We calculated the proportion of health benefit gains (measured as quality-adjusted life-years) resulting from averted and delayed HIV infections; improved health outcomes among PLHIV; and improved health outcomes due to medication for opioid use disorder (MOUD).

RESULTS

The HIV-specific proportion of total benefits ranged from 68.3% (95% credible interval: 55.3-80.0) in Seattle to 98.5% (97.5-99.3) in Miami, with the rest attributable to MOUD. The majority of HIV-specific health benefits in five of six cities were attributable HIV prevention, and ranged from 33.1% (26.1-41.1) in NYC to 83.1% (79.6-86.6) in Atlanta. Scaling up to ideal service levels resulted in three to seven-fold increases in additional health benefits, mostly from MOUD, with HIV-specific health gains primarily driven by HIV prevention.

CONCLUSION

Optimal combination strategies generated a larger proportion of health benefits attributable to HIV prevention in five of six cities, underlining the substantial benefits of antiretroviral therapy engagement for the prevention of HIV transmission through viral suppression. Understanding to whom benefits accrue may be important in assessing the equity and impact of HIV investments.

Evaluation of an HIV Pre-Exposure Prophylaxis Referral System: From Sexual Health Center to Federally Qualified Health Center Pre-Exposure Prophylaxis Clinic

Innovative delivery strategies are needed to facilitate access to HIV pre-exposure prophylaxis (PrEP). The objective of this study was to evaluate a navigator-facilitated PrEP referral process from a sexual health center (SHC) to a co-located PrEP clinic as an alternative delivery model. Electronic health record (EHR) data were used to calculate the number of clients seen at the SHC in 2019. Charts were manually reviewed to determine whether a PrEP clinic referral was made and document type of referral method: face-to-face appointment scheduling with the navigator (warm handoff), EHR messaging to navigator to schedule the appointment at a later time (EHR message), or provision of navigator's contact information to the client (card only). In 2019, 2481 unique potentially PrEP-eligible clients were seen at the SHC; 220 (9%) received a PrEP referral. Of referred clients, median age was 30 years (interquartile range, 24-34), 182 (83%) were male, 89 (40%) were non-Hispanic Black, and 24 (11%) were Latinx. In total, 94/220 (43%) referred clients attended an initial PrEP visit with a provider, and the proportion attending by referral method was 81%, 36%, and 27% for warm handoff, EHR message, and card only, respectively (p < 0.0001). Despite co-location of these two clinics, there were significant drop-offs along the PrEP care continuum for this referral system. Warm handoff was the most effective referral method, but further efforts are needed to understand barriers to referral. Implementation of same-day PrEP services at SHCs is one potential solution to engaging additional clients.