Updates to HIV transmission rate estimates along the HIV care continuum in the United States, 2019.

Background: In 2019, there were an estimated 1.2 million persons with HIV (PWH) and 35,100 new infections in the United States. The HIV care continuum has a large influence on transmission dynamics.

Methods: We updated Progression and Transmission of HIV 3.0, an agent-based simulation model, to estimate 2019 HIV transmission rates and distribution of transmissions by the HIV care continuum, race/ethnicity, transmission group, and age group.

Results: In 2019, the estimated transmission rate in the United States was 2.94 new infections per 100 person-years (inf /100p-y). Transmission rates decreased along the HIV care continuum; the highest transmission rate was associated with persons with acute HIV infection and unaware of their HIV status at 16.35 inf /100p-y, followed by persons with HIV (non-acute) and unaware of their HIV status (9.52), persons aware of their HIV status and not in care (5.96), persons receiving HIV care (on antiretroviral therapy) but not virally suppressed (4.53), and persons virally suppressed (0). The highest transmission rate by transmission group was among men who have sex with men at 3.68 inf /100p-y. Transmission rates decreased as age increased and are similar by race/ethnicity, after accounting for the HIV care continuum.

Conclusion: Our results support a continued emphasis on helping PWH move along the care continuum through early diagnosis, linkage to care, and adherence to ART, resulting in viral suppression to reduce HIV transmissions. Further, efforts should focus on reducing disparities in the provision of HIV prevention and care services, particularly for populations disproportionally affected by HIV.