High-Risk Sexual Practices Contribute to HIV-1 Double Infection Among Men Who Have Sex with Men in Madrid

Longitudinal Changes in, and Factors Associated with, the Frequency of Condomless Sex Among People in Care for HIV Infection, HIV Outpatient Study USA, 2007-2019

During 2007-2019, the percentage of HIV Outpatient Study participants reporting anal or vaginal condomless sex in the past 6 months ranged from a low of 17% among heterosexual males to 59% for men who have sex with men (MSM). MSM reported having had condomless sex more frequently than heterosexual males and females and were the only group in which an increase in condomless sex was observed during the study period (from 39 to 59%). Although persons with undetectable HIV viral load have effectively no risk of transmitting HIV sexually (U = U), there is still the potential risk of transmission or acquisition of other sexually transmitted infections (STIs) when engaging in condomless sex. Continuing education about risks of HIV and STI transmission as well as ongoing screening for and treatment of STIs, retention in HIV treatment, and support for sexual health are critical components of care for people living with HIV.

A Systematic Molecular Epidemiology Screen Reveals Numerous Human Immunodeficiency Virus (HIV) Type 1 Superinfections in the Swiss HIV Cohort Study

BACKGROUND

Studying human immunodeficiency virus type 1 (HIV-1) superinfection is important to understand virus transmission, disease progression, and vaccine design. But detection remains challenging, with low sampling frequencies and insufficient longitudinal samples.

METHODS

Using the Swiss HIV Cohort Study (SHCS), we developed a molecular epidemiology screening for superinfections. A phylogeny built from 22 243 HIV-1 partial polymerase sequences was used to identify potential superinfections among 4575 SHCS participants with longitudinal sequences. A subset of potential superinfections was tested by near-full-length viral genome sequencing (NFVGS) of biobanked plasma samples.

RESULTS

Based on phylogenetic and distance criteria, 325 potential HIV-1 superinfections were identified and categorized by their likelihood of being detected as superinfections due to sample misidentification. NFVGS was performed for 128 potential superinfections; of these, 52 were confirmed by NFVGS, 15 were not confirmed, and for 61 sampling did not allow confirming or rejecting superinfection because the sequenced samples did not include the relevant time points causing the superinfection signal in the original screen. Thus, NFVGS could support 52 of 67 adequately sampled potential superinfections.

CONCLUSIONS

This cohort-based molecular approach identified, to our knowledge, the largest population of confirmed superinfections, showing that, while rare with a prevalence of 1%-7%, superinfections are not negligible events.