It is not a good idea to choose ECs based on what looks “better” on college apps (responding to a comment made above).
I agree about asking around to see if anybody knows of any opportunities. It is hard to get lab experience as a HS student, but ask! Ask your science teacher!
My kids worked in a camp during HS. One of my kids also spent part of the summer cleaning out her school’s yearbook closet, and learned a lot in the process. She was in involved in research right away in college and continued for all 4 years. This included a summer research position in a very well known research hospital. She was also published. She did not have any research experience in HS.
If you are interested in lab work and different medical related ECs, and can get these positions as a HS student….thats great. Talk to people and see if they can help. Talk to the doctor you shadowed, etc.
BUT…if you cannot find what you are looking for, this will not prevent you from achieving your goals in college.
Lastly…working in a lab (in any capacity) is a wonderful experience…but it does not guarantee acceptance to any college. Students are accepted to excellent schools all the time without these experiences.
Adding: there are online science journals for HS students. Why not get a few friends together who share your interests and spend some time reading and discussing?