I think we'll eventually find out COVID-19 has been around way earlier in 2019 than we thought. I've seen both here on HN and elsewhere anecdotal reports of people having a "flu like nothing before" in late 2019 and early 2020 in the US. There's at least one report of Italian doctors seeing a "strange pneumonia" in November (https://www.scmp.com/news/china/society/article/3076334/coro...).
My own story is this. My wife went with her team to a Chinese karaoke bar here in Seattle, in International District, in mid-November. Everyone fell very, very sick (one person has a lingering dry cough to this day). Fever for days on end, cough, etc. It seemed like the flu, except my wife and others claim it just felt different from other times they had the flu.
I caught it from my wife, and it did feel different. I'd never had a fever run for so long, and the way it progressed was just different. And the most unusual thing was that it seemed to affect my heart. I take a beta blocker to control frequent PVCs. But on the days immediately following "recovery" (by which I mean no more fever), I just couldn't move around too much or my heart would start throwing PVCs like crazy, as if I hadn't taken my meds. I was also feeling very weak and faint, which never happened to me before (I'm usually able to exercise just fine right after recovering from illness).
To add to the anecdote, our daughter caught it too but she just seemed to have a mild cold, which also matches the majority of infant COVID-19 cases.
I hope serological tests become widely available, since I'm really curious to know if I actually had it back then. Obviously in the mean time I'm not assuming I did, and I'm staying home and avoiding all human contact I can.