In India at least there are no enrolled course in Medical course for a fifteen year old. Now if you want to shift your field interest then you can go for the diploma courses in Engineering which are applied after class 10. In this course you may get chance to get enrolled in a course like Diploma in Civil Engineering, Mechanical Engineering, Electrical Engineering etc from the polytechnic colleges.

This can be a factor you can see in order to get admission with you eligible age.

To know more about the polytechnic courses you may visit the link below:

https://engineering.careers360.com/articles/polytechnic

I hope my answer helps. All the very best for your future endeavors!