Introduction: The first exposure to high-risk sexual and drug use behaviors often occurs during the period of youth (15-24 years old). These behaviors increase the risk of HIV infection, especially among young key populations (KP)-men how have sex with men (MSM), female sex workers (FSW), and people who inject drugs (PWID). We describe the characteristics of young KP participants in the first Biobehavioral Surveillance (BBS) surveys conducted in Mozambique and examine their risk behaviors compared to adult KP.

Methods: Respondent-driven sampling (RDS) methodology was used to recruit KP in three major urban areas in Mozambique. RDS-weighted pooled estimates were calculated to estimate the proportion of young KP residing in each survey city. Unweighted pooled estimates of risk behaviors were calculated for each key population group and chi-square analysis assessed differences in proportions between youth (aged less than 24 years old) and older adult KP for each population group.

Results: The majority of MSM and FSW participants were young 80.7% (95% CI: 71.5-89.9%) and 71.9% (95% CI: 71.9-79.5%), respectively, although not among PWID (18.2%, 95% CI: 13.2-23.2%). Young KP were single or never married, had a secondary education level or higher, and low employment rates. They reported lower perception of HIV risk (MSM: 72.3% vs 56.7%, p<0.001, FSW: 45.3% vs 24.4%, p<0.001), lower HIV testing uptake (MSM: 67.5% vs 72.3%, p<0.001; FSW: 63.2% vs 80.6%; p<0.001, PWID: 53.3% vs 31.2%; p = 0.001), greater underage sexual debut (MSM: 9.6% vs 4.8%, p<0.001; FSW: 35.2% vs 22.9%, p<0.001), and greater underage initiation of injection drug use (PWID: 31.9% vs 7.0%, p<0.001). Young KP also had lower HIV prevalence compared to older KP: MSM: 3.3% vs 27.0%, p<0.001; FSW: 17.2% vs 53.7%, p<0.001; and PWID: 6.0% vs 55.0%, p<0.001. There was no significant difference in condom use across the populations.

Conclusion: There is an immediate need for a targeted HIV response for young KP in Mozambique so that they are not left behind. Youth must be engaged in the design and implementation of interventions to ensure that low risk behaviors are sustained as they get older to prevent HIV infection.