Study Hypothesis: Social mobilisation will attract and engage young people into decentralised sexual reproductive health (SRH) services where HIV prevention is tailored to need. Decentralised risk informed (differentiated) biosocial HIV prevention will reduce the overall prevalence of sexually transmissible HIV amongst young people aged 15-30. Study aims: 1. Measure the impact of social mobilisation into decentralised SRH services that provide tailored HIV prevention on the prevalence of transmissible HIV. 2. Evaluate the acceptability, practicability, and reach of social mobilisation and decentralised SRH with tailored HIV prevention to deliver differentiated biosocial HIV prevention. Study design: A step-wedge cluster randomised control trial comparing the effect of the Intervention (social mobilisation by peer navigators into mobile nurse-led SRH clinics) with Standard of Care (SoC) at Primary Health Care clinics, in reducing the proportion of 15-30 year olds with sexually transmissible HIV and increased uptake of risk-informed (differentiated) HIV prevention Intervention: Peer navigator social mobilisation intervention includes safe spaces, structured psychosocial and health needs assessment; Peer-mentorship with tailored health promotion, psychosocial support and lay-counselling; provision of condoms, HIV self-tests and pregnancy tests. The mobile SRH clinics provide sexually transmitted infection (STI) care, contraception, HIV testing and antiretroviral therapy (ART) if positive and Pre-Exposure Prophylaxis (PrEP) for those eligible (based on national guidelines) and negative. SoC at Primary Health care clinics includes, contraception, HIV testing and ART if positive and PrEP for those eligible and negative. Population: The eligible population are \ 26,000 15-30-year-old residing in 40 administrative areas (clusters) of the uMkhanyakude district in rural KwaZulu Natal. The 40 clusters will undergo a stratified randomisation to early versus delayed intervention roll out. Data collection: Research data will be collected from four sources: i) three random representative surveys of n= 2000, 15-30-year-olds; ii) programme, process, and clinical data; iii) qualitative data collected during the process evaluation iv) cost data using bottom-up ingredient-based costing and top-down costing using the budgets and expenditure reports. Study Duration: 36 months.