That's a tough one. I try to stay away from the hospital or doctor's office if I can avoid it because that is a place where you have a close grouping of people who are sick. It's amazing that more people don't get sick there. Wearing a mask might help. Taking a probiotic might help get more good bacteria in your gut. That's supposed to be where a lot of your immune system comes from. Of course, wash your hands often.
That's all I've got. Just my opinions, but might help. Hope your grandmother stays healthy!