What factors drive the high HIV incidence in adolescents and young adults (15‑24 years) and what are the most effective biomedical and community‑based prevention strategies?

HIV Incidence in Young People: Drivers and Prevention Strategies

Why Young People Face Disproportionate HIV Risk

Young people aged 15-24 years, particularly young men who have sex with men (MSM) and adolescent girls in sub-Saharan Africa, bear a disproportionate burden of new HIV infections due to a convergence of biological vulnerability, structural inequities, and developmental factors that create unique barriers to prevention. 1, 2

Key Drivers of High Incidence

Biological and Behavioral Factors:

• Adolescent girls in southern Africa acquire HIV 5-7 years earlier than male peers, with up to eight times higher infection rates due to increased genital inflammation, age-disparate relationships, and biological susceptibility 1
• Young MSM, especially Black and Latinx youth in the United States, experience rising incidence while other populations see declines 2
• Developmental invulnerability beliefs lead youth to engage in higher-risk behaviors, viewing HIV as "invisible" due to treatment advances and community stigma 2
• Unprotected anal sex is occurring more frequently among young MSM in urban centers 3

Structural and Social Barriers:

• Lack of healthcare access, inadequate sexual education, and systemic racism create fundamental obstacles 2
• Food insecurity, unstable housing, and limited transportation directly impair prevention program engagement 4
• Gender-based violence, transactional sex relationships, and few years of schooling compound vulnerability in young women 1
• Internalized and experienced homophobia limits open discussion of risk among young MSM 2

Treatment Cascade Failures:

• Youth are less likely to know their HIV status compared to older adults 2
• Lower rates of linkage to care and viral suppression occur in this age group 2
• Injection drug use among young adult heroin users has increased substantially in some areas 3

Most Effective Prevention Strategies

Biomedical Interventions (Highest Priority)

Pre-Exposure Prophylaxis (PrEP):

• Daily emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) should be offered to all high-risk youth, including those with recent STIs, injection drug use, or partners from high-incidence regions 5, 3
• PrEP reduces HIV acquisition by approximately 90% when adherence is high, with 99% risk reduction when tenofovir is detected in blood 4
• Quarterly STI screening at all contact sites and blood syphilis testing is mandatory for youth on PrEP 5
• Acute HIV infection must be ruled out before initiating PrEP to prevent drug-resistant virus emergence 4

Critical Implementation Note: Adherence is the decisive factor—trials showing tenofovir detection in <30% of participants demonstrated no protective effect, highlighting the particular challenge in youth populations 4, 6

Treatment as Prevention:

• All HIV-infected youth should receive immediate antiretroviral therapy (ART) regardless of CD4 count to achieve viral suppression and eliminate sexual transmission (U=U) 5, 4
• Rapid linkage to care after diagnosis is essential, as youth have the poorest retention rates across the HIV care cascade 2

Post-Exposure Prophylaxis (PEP):

• PEP should be initiated as soon as possible for any youth with mucosal or parenteral HIV exposure from a known infected source 3, 5

Behavioral Interventions (Essential Complement)

Individualized Risk Reduction Counseling:

• Multi-session, face-to-face counseling using motivational interviewing achieves superior outcomes compared to single-session or media-delivered interventions, with a number needed to treat of 11 at 12 months 5, 4
• The Explore Study demonstrated 39% HIV incidence reduction over 12-18 months among MSM receiving multi-session counseling 4
• Brief behavioral counseling integrated with biomedical services reduces sexual risk behaviors and increases condom use 4

Condom Provision:

• Condoms remain a cornerstone prevention tool for all penetrative sex acts and should be readily accessible in clinical settings 5, 3

Partner Services:

• Assistance with partner notification, counseling, and testing should be provided to all HIV-infected youth 3

Structural and Community-Based Interventions

Harm Reduction for Youth Who Inject Drugs:

• Simultaneous scale-up of needle and syringe exchange programs, opioid substitution therapy (especially methadone), and ART access can reduce HIV incidence by >90% among people who inject drugs 5, 4
• Low-threshold detoxification and drug cessation programs should be available 3

Healthcare System Modifications:

• Extended clinic hours mitigate barriers related to school/work schedules 4
• Walk-in or "open-access" clinic models with low-threshold care markedly improve viral suppression among youth with complex needs 4
• Patient navigation programs specifically designed for youth increase retention in care 4

Social Support Services:

• Case management addressing food insecurity, housing instability, and transportation barriers improves ART adherence and clinical outcomes 4
• Integration of HIV services with social services and housing programs improves viral suppression 4

School and Community Programs:

• While school-based education programs are commonplace, few have demonstrated efficacy in preventing HIV infection, highlighting the need for evidence-based approaches 1
• Conditional cash transfer programs show promise for HIV prevention in adolescent populations 1

Testing and Screening Strategy

Universal Testing Approach:

• HIV testing at least once for all adolescents and young adults, with repeated testing for those at increased risk 5, 3
• Clinicians must maintain high suspicion for acute HIV infection and pursue prompt diagnostic testing when suspected 3

Serostatus-Neutral Framework:

• Implement a serostatus-neutral approach to reduce stigma: rapidly link HIV-positive youth to care while navigating HIV-negative high-risk youth to PrEP services 5

Critical Implementation Considerations

Combination Prevention is Non-Negotiable:

• No single intervention alone will contain HIV spread in youth populations—biomedical, behavioral, and structural approaches must be integrated 5, 7
• The optimal prevention strategy is the one most acceptable and congruent with the individual youth's routes of potential exposure, preference for administration modality, and ability to adhere 5

Common Pitfalls to Avoid:

• Excluding adolescents from biomedical research creates a massive evidence gap 1, 6
• Assuming youth will adhere to daily oral medications without intensive support leads to PrEP failure 4, 2
• Focusing solely on individual behavior change while ignoring structural barriers (housing, food security, transportation) undermines all interventions 4, 2
• Implementing new prevention methods without engaging with existing traditional practices and youth sexual experiences reduces acceptability 8
• Failing to address systemic racism, homophobia, and gender-based violence perpetuates the epidemic 2, 1

Monitoring and Quality Improvement:

• Systematic monitoring of time from diagnosis to care linkage, retention rates, and viral suppression is essential for identifying ongoing barriers 4
• Real-time surveillance-based messaging through health information exchanges increases re-engagement of youth lost to follow-up 4