Smallpox, yes. But another SARS variant (even a somewhat more aggressive one)...
Obviously, it's not impossible.
But, there were even RNA samples from Covid found in other countries, months before Covid really spread in China.
I imagine the main problem with the superspreader event there was more that enough people ended up in the same hospital, and thus it was easier to identify that Covid was a distinct virus.
If it was crawling around in a less dense population, its spread would've been meh, and the hospitals might not even notice the spike much.
Obviously, it's not impossible.
But, there were even RNA samples from Covid found in other countries, months before Covid really spread in China.
I imagine the main problem with the superspreader event there was more that enough people ended up in the same hospital, and thus it was easier to identify that Covid was a distinct virus.
If it was crawling around in a less dense population, its spread would've been meh, and the hospitals might not even notice the spike much.