Unless you are confident that the risk contact comes from the front, a gown may be good enough (Gown often has openings in the back). But when unknown aerosol transmissible diseases are encountered, we recommend that an EN 14126 certified coverall is more appropriate.
3 solid reasons
Coverall provides protection from head to ankle including the back region.
Coverall is required to pass both fabric and whole garment tests, and a real person is used to simulate actual situation of use.
Coverall with EN 14126 certification will protect you from infective agents.