Recovery of the early season

I would not worry too much about losing fitness. Yes, you will probably have to dial back the duration and intensity a bit, and it may take you a few weeks to get back to where you were at the end of the year, but it's not a big deal. With your race five months out, the bigger danger is pushing yourself to train too hard before you are fully recovered, and then losing still more training time. If you still have a cough, I'd just rest, or at most do some light strength work. Wait until your symptoms are gone and energy levels back to normal before getting back to swim/bike/run. If you are taking care of yourself, that should probably happen within a week or less. If not, maybe see a doctor? Sometimes colds can make you vulnerable to bacterial infections which might require antibiotics or they just linger on and on.

Just be grateful this is five months before the HIM and not (as happened to me last year) three days before the race with full-blown flu and bronchitis.