Sick toddler, I'm due any day now!

So, 2nd time around, I'm 38weeks4days. I have a two year old son who woke with a runny nose and sneeze yesterday. Will it be of harm to my newborn son if his big brother meets him with a runny nose? I never can tell if it's a cold or allergies.. He's congested, clear snot, (only in day 2, right now), sneezy, active and still eating well. Threw up a little bit after breakfast today, but think that's bc daddy gave him too much OJ and was runny around. No fever.