Measurement and interpretation of the Harare HIV combination prevention cascade in priority populations: a population survey of adolescent girls and young women and young men in Zimbabwe.

Introduction: HIV-negative adolescent girls and young women (AGYW), and men (ABYM), have disproportionately high HIV incidence in many African countries. We used a new HIV Prevention Cascade (HPC) approach to quantify levels of, and barriers to, prevention method use to guide interventions to increase effective uptake of primary HIV prevention. Methods: Data from the Manicaland HPC pilot study (2018-19; n=9803) in Zimbabwe were used to measure levels of sexual risk behaviour and construct HPCs for male condom, pre-exposure prophylaxis (females), voluntary medical male circumcision (males) and combination prevention use by HIV-negative sexually active AGYW (15-24 years) and male partners (15-29 years). Results: 19% of AGYW (n=1140) and 37% of ABYM (n=955) who had started sex reported one or more HIV risk behaviour and met the definition of the priority populations for HIV prevention. Of these, 63% of AGYW and 87% of ABYM were motivated to use an HIV prevention method, 28% and 63% had access to a method and 16% and 53% used a method. Male condoms were the most commonly used prevention method, accounting for 97% of use in AGYW and 55% in ABYM. Barriers to motivation, access and capacity to use were reported for all priority populations and methods. Some barriers were common across HPCs (eg, lack of risk perception, social unacceptability and lack of acceptable provision); others were specific to particular prevention methods or priority populations (eg, lack of availability). Conclusion: HIV risk behaviours were commonly reported, but gaps in use of prevention methods exist among young people reporting these HIV risk behaviours in Manicaland. Population survey measurements of HPCs revealed large gaps in all steps in the cascade (lack of motivation, lack of access and lack of capacity to use prevention) and provided information on the reasons for these gaps that can aid in designing interventions that reduce new infections.