R.Q.
If it were me, I would ask her not to visit until she was better. If she does visit, here are some extra precautions to take, just in case. Ask her to wear a mask whenever in close proximity to you or the baby (you never know when a cough, sneeze or hearty laugh will creep up--it'll also remind her "no kissing"). When she (or anyone that's been with her) enters the room, ask them to wash their hands (more than 30 seconds with soap and running water) in addition to any kind of sanitizer that you may use.