Genetic Sequencing Can Evaluate the Effectiveness of HIV Interventions

Reducing the transmission of HIV is critical to preventing epidemics, but for investigators and health care providers it can be difficult to determine if the interventions being utilized to reduce transmission are effective.

In a new study published in the American Journal of Epidemiology, a team of international investigators, including individuals from the Center for Drug Use and HIV/HCV Research at New (CDUHR) York University, have discovered an approach that exploits the evolutionary dynamic of pathogens to track new infections and their origin. The study focused on HIV, but the investigators indicate that the method could potentially be used for different viruses as well.

Although understanding of how pathogens spread has improved over the past decade, preventing disease transmission continues to challenge officials. With the ease of international traveling and more individuals residing within heavily populated areas, pathogens are able to spread more easily than ever before.

Although interventions such as needle exchanges or antiretroviral therapy are in place to decrease transmission within communities, measuring the effectiveness of these efforts is difficult. As such, investigators sought to find out if an intervention would have a community effect—the ability to minimize the spread of disease from individuals directly involved in the intervention to other community members.

To measure this, the investigators simulated a community intervention in people who inject drugs (PWID) using phylogenetics to examine the transmission of the HIV virus from individuals who had been involved in the intervention to individuals infected with HIV after the intervention.

The method involved collecting blood samples from individuals who had been infected with HIV and participated in the intervention, individuals with HIV not involved in the intervention, and individuals recently infected with HIV in a given time period following the intervention.

Using genetic sequencing, the investigators were able to compare characteristics of the virus to determine the source of transmission and whether new infections can be linked to individuals who were involved in the intervention.

“The method provides for the first time a way to quantify the wider social impact of an intervention (community effect),” Gkikas Magiorkinis, MD, MSc, PhD, assistant professor of hygiene and epidemiology, department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Greece, and author of the study told Contagion^®. “For example, new vaccines are tested to measure if they protect the vaccinated people. The protective effect of the vaccination to the unvaccinated community is hard to measure and has never been evaluated. With our new method we could measure such effects and provide evidence in support of wider effectiveness of an intervention campaign.”

The investigators determined that fewer individuals contracted HIV from the population that participated in the intervention, which suggests that the simulated intervention reduced disease transmissions. Additionally, the nature of the simulation provides an innovative method for tracking participants long-term, by collecting blood samples once from each participant and comparing them later on. This is critical in populations such as PWID, where officials often struggle with long-term follow up.

The investigators postulate that this innovative method can be applied to assess the effectiveness of interventions for infections beyond HIV; in fact, according to Dr Magiorkinis, the investigators “have plans to test this method in HCV and vaccination trials.”