Coding 15-year-olds who were vertically infected with HIV

[jennifersmith203]

Currently all 15-year-olds enter the model HIV-negative. ZIMPHIA data suggests that 2-3% of 15-19 year-olds were infected vertically rather than sexually so we may want to code this into the starting population. As well as HIV status, we would impute treatment history, resistance status, date of diagnosis etc.