Adolescents and young adults on antiretroviral (ARV) treatment for HIV may episodically develop a significant risk of transmitting the virus. Not only are they less likely to maintain a fully suppressed viral load than older people with HIV, but they are also more likely to contract sexually transmitted infections (STIs), which raise their risk of transmitting HIV to others.

To assess such long-term risk, researchers conducted a retrospective cohort study of individuals between 13 and 24 years old receiving ARV treatment at the adolescent HIV clinic at the Children’s Hospital of Philadelphia between 2002 and 2015. Sarah M. Wood, MD, of Children’s Hospital and the University of Pennsylvania Perelman School of Medicine, presented findings from the study at the 9th International AIDS Society Conference on HIV Science in Paris (IAS 2017).

For their analysis, the investigators included all study visits after the participants started ARVs at which a viral load test result was registered. They categorized the participants as being at high risk for transmitting the virus to others if at that time they had a viral load greater than 1,500 and were diagnosed with gonorrhea, chlamydia or syphilis. Pairing these two factors made for a more conservative model than looking at just viral load, meaning the researchers results likely underestimate young people’s long-term risk of transmitting HIV while on treatment for the virus.

A total of 240 participants were followed for a median 3.2 years, providing data from 2,661 study visits. Eighty-seven percent (209) were African-American, 73 percent (173) were male, 7 percent (17) were transgender females and 49 percent (117) had a history of STI diagnosis prior to entering care at the clinic or were diagnosed with an STI upon entry into care.

Seventy-three percent (176) of the participants had some form of transmission risk during the study, including: 21 percent who only had a viral load above 1,500; 27 percent (64) who were  diagnosed with only an STI; 8 percent (19) who had a viral load above that threshold and received an STI diagnosis but not at the same time; and 17 percent (4) who were at high risk of transmission because they had a viral load above the threshold and had an STI at the same time.

Fifty-nine percent of the participants had public insurance, 18 percent had private insurance, 7 percent received Ryan White CARE Act funding and 16 percent were uninsured.

After adjusting the data for various factors, the researchers found that being diagnosed with an STI upon entering HIV care or having a history of prior STI diagnosis was associated with a 3.09-fold increased risk of later entering a period of high risk of transmitting HIV.

The study authors concluded that their findings emphasized the need for interventions that encourage better adherence to ARVs as well as STI risk reduction among HIV-positive young people.