According to the US Centers for Disease Control and Prevention (CDC) and other sources, there are about 1.2 million people with HIV in the United States and another 1.2 to 2.2 million who are at the highest risk of infection and could benefit from the preventative measure known as HIV prophylaxis (PrEP).
The HIV viral load test – a laboratory measurement of the amount of HIV in someone’s blood – is used to diagnose HIV infection in its early stages, monitor the effectiveness of antiretroviral therapy (ART) in keeping the virus at undetectable levels, and assess whether the virus has developed resistance to ART.
However, one question about viral load testing has remained unanswered: Does knowledge of an HIV viral load test result increase rates of “linkage to care” to seek ART for active infection or PrEP if uninfected but at high risk?
In a study published today in JAMA Network Openresearchers at Johns Hopkins Medicine and the CDC report that the answer may be no.
“We conducted a randomized clinical trial of 195 adults – including people living with HIV but not taking ART and people identified with risk factors [such as multiple sexual partners, evaluation for sexually transmitted infections or injection drug use] for acquiring HIV,” says lead study author Matthew Hamill, MBCh.B., Ph.D., MPH, associate professor of medicine at Johns Hopkins University School of Medicine. “We randomized 98 people to the intervention group who received next-day HIV viral load testing and standard of care [SOC] HIV test and 97 subjects in the control group who received SOC HIV test only. We then followed them for 12 weeks to see if they sought care during that time, and if so, when exactly that happened.”
Hamill says linkage to care is defined as a person seeking care for a diagnosed medical condition or to start preventive treatment. “For example, when a smoker joins a smoking cessation program or a pregnant woman starts seeing an obstetrician for prenatal care, that counts as a link,” she explains.
The majority of study participants were between the ages of 27 and 47, with an average age of 36. 39 percent were female, 57.4 percent were black, 26.2 percent were white, and 16.4 percent were of other ethnicities. The majority of participants (63.1%) were recruited between August 2021 and January 2023 by a Baltimore, Maryland emergency department, with the remainder (26.7%) enrolled through social media campaigning and other means.
The median time for participants to receive their test results was six hours for a standard-of-care test (detection of HIV antigen/antibody only) and 26 hours for a viral load test (quantification of the number of HIV particles in the blood sample).
“Overall, 93 participants out of a total of 195, or 48%, attended the 12-week follow-up visit with one of our team members, and 69, or 35%, were linked to care by that time,” says senior study author Yuka Manabe, MD, professor of medicine at the Johns Hopkins University Center of Medicine School of Innocents for Innocents. “Overall, we found that there was no difference in care rates between groups, suggesting that knowing the results of a viral load test does not significantly improve the rates at which people seek HIV treatment or prevention care.”
However, Manabe says a subgroup of those who received a viral load test — participants living with HIV — had higher rates of linkage to care, even if it took a day to get results.
Hamill and Manabe suspect that rates of linkage to care would be higher overall if people received their viral load results earlier than one day after testing.
“That’s one of the things we hope to study in future clinical trials: Does more immediate feedback about viral counts influence people to start treatment or preventive care right away?” Hamill says. “We also want to see if it helps to offer PrEP treatment right after a person tests HIV negative. It’s more effective than saying, ‘Come back in a week when your lab results are ready.'”
Along with Hamill and Manabe, the research team members from the Johns Hopkins University School of Medicine are the study’s first author M. Harris Bayan, Tanique Bennett, Alec Boudreau, Zoe Demko, Susan Eshleman, Yu-Hsiang Hsieh, Nyah Johnson, Agha Mizra, Richard Nizra, Elizabeth Nizra, Elizabeth Nizra. Travis Smalls and Thelio Sewell. Team members from the CDC are Pollyanna Chavez, Kevin Delaney, Nathalie Gonzalez-Jimenez, and Robin MacGowan.
Federal funding for the study comes from CDC grant U01PS005204-01-00.
Hamill was a paid speaker for Roche Diagnostics, a company that provided a product used in this study.
