# 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

## TL;DR

The study models how faster HIV diagnosis and immediate treatment can reduce HIV transmission among men who have sex with men in the Netherlands.

## Contribution

A novel agent-based model is used to simulate the impact of accelerated early HIV diagnosis and immediate ART initiation on transmission among MSM.

## Key findings

- A 32-fold increase in early diagnosis within 3 months could avert up to 269 HIV infections over 10 years.
- Immediate ART initiation after diagnosis does not significantly affect transmission dynamics.
- Extending diagnosis to 6 months post-infection with an 8-fold increase could avert 256 infections.

## Abstract

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.

In recent years, in the Netherlands, the annual number of new HIV infections in the population of men who have sex with men (MSM) is declining. Using an agent-based model calibrated to the current state of HIV epidemic in MSM in the Netherlands, we explored the potential impact of an intervention that accelerates diagnosis in individuals with early HIV infection and facilitates immediate antiretroviral therapy (ART) initiation to reduce the number of new HIV infections in the population of MSM even further. Our projections indicate that such an intervention can noticeably reduce onward HIV transmission in the population of MSM. Increase in diagnosis rate by a factor of 32 for individuals with early HIV infection results in the impact close to the maximum (simulated by modeling newly infected individuals instantaneously starting ART), but still leaves the room for improvement. Extending the intervention to target individuals who acquired HIV infection within the previous 6 months could by a factor 8 could result in similar number of HIV infections averted. Immediate initiation of ART following the diagnosis while key in order to prevent deterioration of CD4 cell count, does not have significant effect on the HIV transmission dynamics. The intervention which achieves increased diagnosis rate in individuals with early HIV who then immediately initiate ART, can bring forth substantial reductions, even against a backdrop of an already declining trend.