My D thought diseases - everything from physical ones like Ebola to mental ones lie sleep disorders - were fascinating. She was interested in neuroscience first, then epidemiology. She took a pre-college course in each, did an independent study through her HS/a local college with one. Thought about med school but really liked epidemiology.
She applied to college as likely Chem major but changed her mind…but her interests were consistent throughout most of HS in that way. She read books on epi/pandemics, she took Env Sci because she as interested in the ways environment affects disease, she loved math and science anyway so took a lot of that.
I’m not sure she ever had a goal like you’re talking about, but being part of,say, eliminating Zika would have been the sort of one she’d have named as a HS senior. Maybe she did - I didn’t read all her essays 