[blagie]

Well, a few explanations I can think of:

1) Covid19 was circulating, but had it's first outbreak in Wuhan due to things like population density

2) Covid19 was circulating earlier than China informed the world know (I'm not claiming grand conspiracy here to keep things secret; the simplest explanation is China didn't figure out what was happening for a while)

3) There were other coronaviruses with the same or similar proteins elsewhere.

I'm leaning towards #3. It makes a heck of a lot of sense for a lot of things unexplainable with SARS-COV2. If there was a mild cold circulating similar to SARS-COV2, but less deadly and less contagious, it'd explain a lot of the epidemiology (for example, why waves break so early, rather than infecting 70-90% of the population).

[tremon]

the simplest explanation is China didn't figure out what was happening for a while

It's even simpler than that: there was no need to figure anything out. If a few people present with flu-like symptoms but appear to suffer above average from it, Occam's conclusion would be that those people may have had an underlying condition that exacerbated the severity of their flu. There is zero need to go looking for zebra's until you identify a cluster of similar cases that all have above-average severity.