I often work when I shouldn't because I have limited time to take. There are certainly days I don't bike when I'm this sick. Actually, two weeks ago I was still sick after turkey day weekend and I got back on the bike. It made it way worse and I ended up having to miss a day, and then take two more off of commuting to recover. So, I wish I had driven, but I thought I was over it.
I think you can tell...if you can't then it's best to play it safe.