With my last daughter I was breastfeeding and she didn't get sick once until I quit (6mo)because she was getting my anti bodies.. But I still avoided sick people and when I ended up with strep throat I wore a mask while nursing. No clue if any of this was helpful or not
If you are in one of the states with the crazy virus that is going around I probably would otherwise I wouldn't. I only exiled my husband when he had a horrible cough with ds1 and that was more because he was waking us both up.
I actually came down with a pretty bad cold when my first was 4 or 5 days old. Despite staying home with him and being in constant contact, he didn't get sick. I wouldn't exile your husband unless he has a fever or serious cough. If it makes you more comfortable, maybe they could have less contact, but I wouldn't cut them off from each other entirely.
Re: 11 day old newborn - DH has sore throat!!
Unfortunately I'm not breast feeding, still recovering from having severe preeclampsia. This just makes it harder on me that I'm not.