I had the typical omicron symptoms back on NYE (triple vaxxed and a hermit and I still got it somehow). I had 3 days of awfulness where my throat got so swollen that I couldn't even speak by the end of the day. Then I had about 7 additional days where I just felt generally tired and "off" mentally and physically. I didn't run at all during that time...at most, I soft pedaled on a bike for 30-60 minutes.

After 10 days, I was almost back to normal. However, my heart rate kept skyrocketing while exercising for another 2ish weeks. In all, it took about 3 full weeks for my HR to settle and for me to return to 100%. My doctor friends said that my timeline and experience was about right on with what they had been hearing re: omicron.

Just be prepared to have to take easy for longer than expected. My fitness personally came back just fine. And once my HR settled, I had no problems ramping up the training. I just wish it wouldn't have taken so long.