Monitoring HIV Strains to Prevent PrEP Failure, Viral Transmission

High levels of viremia combined with tenofovir (TDF) and emtricitabine (FTC) resistance were rare in a cohort of more than 7000 people with human immunodeficiency virus (HIV) in King County, Washington, according to a study published in PLoS One.

“Monitoring trends in TDF/FTC resistance coupled with interventions to help ensure people living with HIV achieve and maintain viral suppression may help ensure that pre-exposure prophylaxis (PrEP) failure remains rare,” wrote University of Washington researchers. 

Transmission of a viral strain with mutations conferring resistance to PrEP components TDF and FTC has occurred, but public health officials are uncertain as to what extent such strains are circulating. To better understand the situation in King County, which is located in the Seattle metropolitan area, investigators analyzed HIV surveillance data to gauge primary and overall resistance to TDF and FTC and concurrent viremia. Primary resistance was defined as identified within 3 months of HIV diagnosis, and total resistance reflected identification at any time.

When researchers looked at trends in primary resistance from 2010 to 2019, they found a 0.2% rate of primary TDF/FTC resistance with both K65R and M184I/V mutations.

“Adding isolated resistance for each drug resulted in 0.3% with primary TDF resistance and 0.8% with primary FTC resistance,” they wrote.

In 2019, the rate of total TDF/FTC resistance at any time was 6%, according to the study. The rate of simultaneous occurrence of both viremia and TDF/FTC resistance was 0.2%.

“We found that 0.2% of individuals newly diagnosed with HIV in King County had primary TDF/FTC drug resistance and, similarly, 0.2%, of PLWH living in King County in 2019 had both TDF/FTC resistance and viremia,” researchers wrote. “We found no evidence of increasing primary TDF/FTC resistance during the 10-year period 2010–2019 despite widespread adoption of PrEP among local MSM [men who have sex with men], with nearly half of MSM at high-risk for HIV using PrEP by 2018.”

To ensure PrEP failure rates do not increase, study authors recommended that stakeholders monitor trends in TDF/FTC resistance and implement interventions to achieve viral suppression among people living with HIV.

Reference:
Buskin SE, Lechtenberg RJ, Slaughter FA, et al. A public health approach to monitoring HIV with resistance to HIV pre-exposure prophylaxis. PLoS One. 2022;17(8):e0272958. doi:10.1371/journal.pone.0272958