HIV Risk Among Injectable Drug Users Impacted by Diversity

FEBRUARY 23, 2018
Jared Kaltwasser
Kumi Smith, PhD
A new study offers a roadmap for how tracking social interactions can lead to better prevention of HIV infection among users of injectable drugs.

Researchers from the University of North Carolina (UNC) tracked a patient population of males who inject drugs in the northern Vietnamese city of Thai Nguyen, the site of UNC’s
Project Vietnam, an NIH-funded HIV and intervention site.

As people who inject drugs (PWID), the 1139 patients covered by the study are in an at-risk population for HIV infection. According to the Joint United Nations Program on HIV and AIDS, just 0.4% of people ages 15 to 49 years are infected with HIV, but among PWID, the HIV infection rate is 11%. However, the risk of contracting HIV isn’t spread equally among the PWID population, the study found.

For instance, people with HIV in the 30- to 34-year age group and people in the 35- to 39-year age group had the highest rates of transmitting HIV to others. Meanwhile, those aged 25 to 39 were at the highest risk of contracting HIV.

Part of the reason the researchers were able to come to those conclusions was that they were able to calculate the various ways PWID share needles. Those 1139 patients were involved in some 2070 “equipment sharing partnerships,” meaning many patients traded needles with multiple other drug users. The researchers also found that people who shared injection needles tended to do so with people in their same age cohort.

Kumi Smith, PhD, the study’s lead author, told MD Magazine that the Vietnamese study can act as a proof of concept for similar research elsewhere.

“I think our Vietnam study could be a good model for how a similar study of American PWID might be done,” she said. “It’s possible that mixing patterns in PWID are universal across all cultural settings, but we know too little about it to be sure of that yet.”

In the case of the Vietnamese patients, Smith said her research suggested that those PWID who are ages 30 to 39 would be the best candidates for the treatment as prevention (TasP) HIV strategy. Meanwhile, those ages 25 to 39, who face the highest risk of contracting HIV, ought to be the targets of pre-exposure prophylaxis efforts (PrEP).

Smith said there is evidence that these types of measures can be effective for people whose primary risk factor is the use of injectable drugs. However, she said knowing what works doesn’t solve the thorny problem of finding a way to successfully implement the strategies.

“[T]he implementation challenges are myriad–e.g. how to get PrEP approved in places where injection drug use is severely criminalized, how to improve acceptability and accessibility of PrEP for PWID, addressing provider willingness or lack thereof for prescribing PrEP to PWID, etcetera,” she said.

Aside from lending credence to potential prevention strategies, Smith wrote that the study is also important because it provides hard data that can be used to develop better mathematical models that take into account social mixing patterns.

The study, titled “Using Contact Patterns to Inform HIV Interventions in Persons Who Inject Drugs in Northern Vietnam,” was published in the Journal of Acquired Immune Deficiency Syndrome.

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