Rapid HIV Transmission Bursts: A Closer Look at Future Risks

A groundbreaking study led by Rachael M. Billock, PhD, MSPH, from the Division of HIV Prevention at the Centers for Disease Control and Prevention (CDC), Atlanta, has shed light on the dynamics of HIV transmission bursts. Published online on December 24, 2024, in the AIDS journal, the research analyzed data from 101,395 HIV sequences sourced from the National HIV Surveillance System. This study focused on adolescents aged 13-19 years and individuals aged 60 years or older, offering insights into how rapid transmission bursts impact future transmission risks.

The study revealed that adolescents aged 13-19 years were 6.27 times more likely to be part of transmission bursts compared to their older counterparts, those aged 60 years or older. Transmission bursts were defined as instances where three or more consecutive transmission episodes descended from a single lineage within the detection period. These bursts played a significant role, contributing to 14.9% of all transmission events recorded between 2017 and 2019.

Through phylogenetic analysis across six geographic regions in the United States, the research explored how these bursts influenced future transmission. The findings showed that lineages involved in transmission bursts contributed 2.94 times more to future transmission events than those not entangled in such bursts.

"Lineages involved in transmission bursts contributed to nearly three times as many future inferred transmission events as those not involved, demonstrating the importance of timely detection and response to interrupt heightened transmission," said Rachael M. Billock, PhD, MSPH, from the Division of HIV Prevention at the CDC in Atlanta.

The study also noted that individuals diagnosed with HIV during acute or early infection were 1.40 times more likely to be identified as members of transmission bursts than those diagnosed later. Data covered persons diagnosed with HIV between 2014 and 2019, with financial backing from the CDC and partial funding from the National Institute of Allergy and Infectious Diseases.