Estimating the impact of combined prevention interventions targeting 15-24 years-old men and women in nyanza, Kenya

Background: Young males (YM) and especially young females (YF) (age 15-24) in sub-Saharan Africa are at a higher risk of HIV infection compared to older adults. HIV testing of young individuals facilitates early identification of their ‘HIV+' status, prompt ART initiation, and provision of male circumcision and PrEP. We hypothesize that youth-prioritized combination interventions could have substantial impact on HIV incidence among them and the wider adult population. Methods: Using an age-sex-risk stratified mathematical model representing HIV heterosexual transmission in Nyanza, Kenya, we estimated the impact of leveraging HIV testing and counseling among Nyanza youth, prompt ART initiation (at CD4<=50 cells/mm3) based on knowledge of status, and further gender-specific intervention components: male circumcision for YM and reduction of partners and PrEP for YF. Results: We predict a reduction in HIV incidence over 10 years among youth by 34% (from 1.6% /person-years) and adults by 29% (from 1.3% /person-years), if the annual testing likelihood for youth increases to 90% (from 13%) with newly HIV-diagnosed youth increasing condom use by 30% and initiating ART promptly. The adult incidence is reduced 41% and 37% by further male and female specific interventions. The full combination package would decrease incidence by 60% and 48% among youth and adults; respectively. Conclusions: In populations where young people are at the highest risk of HIV infection, carefully prioritized, gender-specific intervention can have a substantial impact on the risk of infection, both in that group and the population overall.