Q. Is it appropriate to add a semicolon before i.e. or e.g.? For example, is it correct to say “by focusing on prevention; i.e., identifying and intervening”?

A. You can use a comma unless the material after the abbreviation starts a new independent clause.

She carried only the essentials, i.e., business cards, lipstick, pepper spray.

She saw to the last two details; i.e., flowers were waiting and the driver kept mum.

In either case a colon, an em dash, or parentheses might also work. And please note that Chicago doesn’t use i.e. or e.g. in running text (though we allow them in parentheses or notes). We use that is or a similar phrase. In many sentences (such as mine), you don’t really need the abbreviation; a colon or dash alone would be better.