Sickness Prevention Help Needed

So I picked my 2yr old up from daycare today and they told me he has a low fever (99.5) and that he skipped his snack (which he never does). Other than that, they said he was fine. As soon as we got in the car I knew he wasn't feeling good. He was quiet, zoned out, and looked miserable. We got home and he threw up all over the kitchen. I gave him a bath, but now I'm freaking out because I have a 16 day old newborn and I really don't want her to get sick. I was told any fever or vomiting with her would result in a trip to the ER for a 2 day hospital stay and a spinal tap to rule out anything worse (until she turns 2 months old). I'm keeping my son home from daycare tomorrow, but any advice as to how to prevent my newborn from getting whatever my son has? I'm washing all of his things and hand sanitizer is my best friend.