We have annualized influenza numbers so seasons are comparable year over year.

I'm going to guess CoVID needs the same treatment? Are we going to continue with this being one massive outbreak, or will this 2021 year be basically treated as the first annual winter season for this virus?

I'm going to guess for now we keep adding numbers to the initial outbreak as it is new, but by this time next year we start treating it as an annual seasonal virus and start looking at cyclical annualized data?

If its cyclical, where's the trough?

Not all viruses are seasonal. Covid is still too new to say whether it is or not. For example, South Africa is at its worst right now - in the middle of their summer season.

Seasonality aside, I think you'd have to see a lot more re-infections pollute the stats before they decide to move away from calling it an outbreak. Right now, they're thankfully still very rare, and my naive hope is that they stay that way... but realistically, yeah, we're probably looking at annualizing stats at some point in the next couple years.