I just had a week off with a flu went back to training on SAturday and about to go in this morning. Would expect to take at least two weeks to get back to peak. Just need to get a couple of really hard sessions.
I was ill and i took 3 weeks off, i feel healthy but not very fit, i don't think a week off will do too much, sometimes its a benefit, 2 weeks is a good rest. but anything over 3 weeks will be negative if you train regular.