When it comes to improving the various stages in the HIV care continuum, focusing on improving retention of people in care for the virus is the most effective way to drive down infection rates, according to a new modeling study. The simulation made projections about how the United States could cut in half the annual number of new cases of the virus by 2025.

According to the most recent estimate from the Centers for Disease Control and Prevention (CDC), an estimated 1.1 million people are living with HIV in the United States. Among these individuals, an estimated 85 percent have been diagnosed, 62 percent have been linked to medical care for the virus, 48 percent are fully retained in care and 49 percent have a fully suppressed viral load. These various steps are collectively known as the HIV care continuum, or treatment cascade.

Because having a fully suppressed viral load is associated with effectively no risk of transmission of HIV, according to the CDC, efforts to better guide people living with the virus through the care continuum and to that endpoint will likely drive down the overall rate of transmission of the virus.

Publishing their findings in Open Forum Infectious Diseases, researchers used a mathematical model of HIV transmission as related to testing of the virus, linkage to care and retention in care to determine how shifts in each point in the care continuum would help achieve the goal of halving HIV transmissions by 2025.

According to the most recent estimates 36,000 to 39,000 U.S. residents currently contract HIV annually.

The researchers found that it was not possible for their mathematical simulations to yield a projected halved HIV transmission rate by 2025 if more than 20 percent of people engaged in HIV care dropped out of care annually, even if they returned to care at high rates.

If those linked to care were retained in care at a rate of 95 percent and those who dropped out of care reengaged in care within 1.5 years on average, there was about a 90 percent probability that HIV incidence would indeed drop by 50 percent by the target date. Consequently, the researchers stated that U.S. programs should strive to meet these engagement and reengagement figures.

According to the investigators’ projections, raising the annual rate of people with HIV’s retention in care by 10 percentage points above a rate of 80 percent increased the likelihood of halving the HIV infection rate by 2025 by 25-fold. Raising the annual rate of reengagement in care by 10 percentage points raised the likelihood of hitting this target 2-fold.

Increasing by 10 percentage points the annual rate of screening of high-risk individuals, the rate of screening of low-risk individuals or the percentage of people living with HIV who are linked to care for the virus annually did not have a significant projected effect on the likelihood of halving HIV incidence by 2025.

To read the study, click here.