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 would also work—and in the first example, any of those marks would be preferable to the comma. Please also 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. See also CMOS 6.54.