Prevention and preventive care are typically classified separately, although it's a bit of a gray area. US residents on health plans receive free access to preventive services including immunizations, screening tests, etc.

https://www.healthcare.gov/coverage/preventive-care-benefits...

But prevention is largely outside the scope of medical care. For issues like diet, exercise, and avoidance of substance abuse patients may be able to get help from a variety of other sources including public health agencies, therapists, social workers, dieticians, personal trainers, etc.