I've just recovered from a chesty cold. Was really cautious and took most of the week off running. Figured that my body could really object to the pressure and a few days is better than really hurting myself.
But, I've totally hated it. Felt heavy, lazy and a bit crap. Soon as clear off chest, back to it and felt really strong. So the rest may have helped.
You've got ages yet, as do I. My first is end of April. Don't worry. Easy to say, but get better, flu is very, very nasty, don't underestimate it.
Hope this helps a bit.