There is this special polymer armor, I forget the specific name of the material, that is light and can be made in a rating between level III and IV, meaning it will stop a hot loaded M193 round from a 20 inch barrel. Which is normally the worst threat. When they first came out those plates were cheap, but the price want up fast last time I looked a couple of years ago.While not shield specific, individual armor has come a long way as well. In the pic below, the thinner plate on the left comes with our standard soft armor vests issued to patrol. When used in-conjunction with, it provides IIIA protection. At just 1/2 thick and just under 1.5 pounds, you really don't know you're wearing it.
The plate on the right is 1" thick, 2.4 pounds, and offers level III and some level IV stand alone protection.
I keep both handy in my front seat and can slip either one of them down my shirt and into my vest in seconds.
Most armor leaves many parts of the body exposed. A hit at under a 100 yards from a 308 hunting rifle with lighter highspeed frangible bullets would destroy a lot of tissue for a hit under the vest. Maybe one might survive it with immediate advanced care. One hit over the vest could certainly result in death due to destruction of major blood vessels or neural CNS anatomy even with quick access to an ER.