Ease of Early HIV Transmission Is Overestimated

Commonly cited estimates on how easily newly infected patients transmit HIV may be vastly overstated.

In a study published in PLOS Medicine, researchers aimed to reevaluate the duration and relative infectivity of a months-long, acute-phase HIV-1 infection, while also considering sources of bias in previously published literature.

The analysis examined viral load trajectories and viral load—infectivity relationships to estimate the relative hazard of HIV transmission in the acute and chronic phases. The review included data that the researchers felt had been overlooked in other studies, such as underlying differences in HIV infectiousness and susceptibility among participants.

Similar to previous studies, the authors determined that the risk of HIV transmission is higher in the acute phase than the chronic one. However, they found that the additional transmission risk attributable to the acute phase is equivalent to 5.6 extra months of chronic-phase infection, which is significantly lower than the previously estimated range of 31 to 141 excess hazard-months.

This finding suggests that newly infected patients are also less likely to undermine antiretroviral treatment as prevention strategies than prior research has indicated. In contrast, programs solely focused on the early identification of HIV patients may not be as cost-effective for controlling infection transmission, the researchers noted.

“One of the biggest challenges to eliminating HIV is diagnosing people before they have the chance to infect others,” said study author Lauren Ancel Meyers, PhD, in the statement. “If newly infected people are not as infectious as previously believed, then we can be more optimistic about the global impact of HIV ‘treatment as prevention’ efforts.”

Lead study author Steve E. Bellan added that such efforts to control HIV “may be even more effective, and it can help communities to direct public health resources to save more lives."

“These revised estimates—and the impact of heterogeneity of HIV infectiousness and susceptibility to infection on HIV transmission within populations revealed by this analysis—should now be considered when designing population-scale interventions and when communicating individual-level risk of HIV transmission and infection in clinical and community settings,” the journal editors wrote.