If you have two or more in daycare, what has your experience been like with illnesses? Is it twice as bad as a single child or does the older kid stop getting sick as often?

We've been through the ringer this year with illnesses and were planning to TTC #2 soon but looking back at what we've gone through over the past 6 weeks alone (HFM, roseola, AND strep throat), I'm starting to wonder if I'm crazy for thinking about it. LO is 22 months if that makes a difference. I wish I could say it was just her getting sick, but most of the time we all get it (still can't believe I got HFM), so that's where I get worried.