Early initiation of antiretroviral therapy (ART) can lead to a sustained decrease in genetically linked HIV-1 infections in sexual partners, according to a new study.
HIV-1 prevention strategies are required to reduce the risk of viral transmission among sexual partners, and studies suggest that ART in those with HIV-1 infection reduces the risk of sexual transmission of the virus, stated the researchers, led by Myron S. Cohen, MD, of the University of North Carolina Institute for Global Health and Infectious Diseases.
The researchers published the final results of the HIV Prevention Trials Network (HPTN) 052 trial on September 1, 2016 in the New England Journal of Medicine.
An interim analysis of data from the trial showed that ART prevented more than 96% of genetically linked infections caused by HIV-1 in serodiscordant couples. ART was then offered to all patients with HIV-1 infection (index participants), who were followed for more than five years to assess the durability of preventing HIV-1 transmission.
The 1,763 index participants were randomly assigned to receive either early or delayed ART. In the early-ART group, 886 participants started therapy at enrollment (CD4+ count, 350 to 550 cells per cubic millimeter). In the delayed-ART group, 877 participants started therapy after two consecutive CD4+ counts fell below 250 cells per cubic millimeter or if they developed an illness indicative of the acquired immunodeficiency syndrome (an AIDS-defining illness).
Index participants were followed for 10,031 person-years and their partners for 8,509 person-years. Among partners, the researchers observed 78 HIV-1 infections (annual incidence, 0.9%). Viral-linkage status was determined for 72 (92%) of the partner infections; 46 infections were linked (three in the early-ART group and 43 in the delayed-ART group; incidence, 0.5%) and 26 infections were unlinked (14 in the early-ART group and 12 in the delayed-ART group; incidence, 0.3%).
Early ART was associated with a 93% lower risk of linked partner infection than was delayed ART. No linked infections were observed when HIV-1 infection was stably suppressed by ART in the index participant.
Eight genetically linked partner infections were observed after the index participant had initiated ART (three in the early-ART group and five in the delayed-ART group). In all eight cases, the index participant was most likely viremic at the time of HIV-1 transmission, although it was not possible to measure the viral load at the time of the transmission event. “The relationship between viremia and HIV transmission that we observed in this study emphasizes the importance of counseling with respect to the potential for HIV-1 transmission before viral suppression is achieved, of close monitoring of the viral load during treatment, and of responding quickly in cases of ART failure,” the researchers stated.
In conclusion, the researchers stated: “The final results of the HPTN 052 study show that successful treatment of HIV-1 is a highly effective tool for the prevention of sexual transmission of the virus,” adding “we hope that the newly emphasized importance of early initiation of ART will encourage patients with HIV-1 infection to start such therapy without delay.”