Possibly dumb question, what about the people who have been told by their doctor to NOT get a covid vaccine because of specific pre-existing conditions or medic

Possibly dumb question, what about the people who have been told by their doctor to NOT get a covid vaccine because of specific pre-existing conditions or medical history? My neighbor has been told by his doctor to not get any vaccine because of his medical history. Are those people just SOL, or am I missing something? THX