[DiogenesKynikos]

How am I wrong?

There were countless spillover events for the original SARS. To this day, it's not known precisely how many SARS spillover events there were, because they were so numerous and tracing was so poor back then. In a different comment in this thread, I cited a review article that goes over the evidence for widespread spillover events of SARS in 2002-2003.[0]

The gist of it is that SARS popped up independently at numerous markets, dotted across the Pearl River Delta. SARS infection was very common among palm civet traders in the region (it's even possible that most of them became infected).

The lab leaks came later, after huge interest emerged in the new virus and it started to be cultured in large quantities in many labs. Those leaks were extremely rare compared to the spillover events, they were immediately detected, and they led to much stricter lab security practices. But the relative probability of a novel virus that nobody even knows they have initially leaking from a lab vs. spilling over from large animal populations that host the virus is basically nil.

0. https://link.springer.com/chapter/10.1007/978-3-540-70962-6_...

[COGlory]

You're mixing up animal > human transmission, and zoonotic events. They are not equivalent. Human SARS spike protein RBD could bind palm civet ACE2, but not vice versa. Palm civets (and other animals) could act as reservoirs for human SARS, (as well as non-human SARS, which contributed to the zoonotic event), but that's not the same as a new virus jumping species. It's more like getting rabies from a raccoon.

It's possible that the original SARS jumped 3 times total, based on the genetic evidence, but the later two we don't really know because of the hinam -> animal route. Still, with the number of laboratory acquired infections of SARS-CoV-2, it doesn't really tip the scales.

[DiogenesKynikos]

> It's more like getting rabies from a raccoon.

If rabies were a novel virus that had never infected humans before, you could make the comparison. SARS was a novel virus, which spilled over into humans in a very similar manner to SARS-CoV-2 (wild animal markets in a major Chinese city).

> It's possible that the original SARS jumped 3 times total, based on the genetic evidence

As the review I cited explains, the epidemiological and serological evidence makes clear that SARS independently jumped over to humans at many different locations, over the course of months.

[COGlory]

I read the review. There are many cases of this:

> It's more like getting rabies from a raccoon.

And only 3 potential cases of this:

> It's possible that the original SARS jumped 3 times total, based on the genetic evidence

You're saying animal -> human transmission of a human virus is equivalent to animal -> human transmission of a new virus. Those are two *extremely* different things. The palm civet SARS spike protein RBD did not gain the ability to bind human ACE2 many times. In fact, the evidence for that seems to only be a single time. The remaining two suggested origin events show mutation of the existing virus, followed be retransmission across species barriers.

Those are two completely different types of events.

[DiogenesKynikos]

> You're saying animal -> human transmission of a human virus is equivalent to animal -> human transmission of a new virus.

You're making up an entirely arbitrary distinction.

> The palm civet SARS spike protein RBD did not gain the ability to bind human ACE2 many times.

You have no idea if this is the case. Most of these small outbreaks were not analyzed in detail (or even known about until well after the fact). The evidence shows that the virus was able to jump from animals to humans numerous times, and possibly spread in small clusters.

[COGlory]

No, they're two very different things, because one involves an adaptation. Once adapted, the rules of the game for cross-species transmission events are completely different.

Or do you maintain that a combination cross-species transmission and adaptation to the new host is as common as cross-species transmission of already-adapted viruses?

[DiogenesKynikos]

I see that you're trying to imply that SARS-CoV-2 was pre-adapted to humans, while SARS wasn't, so this is going in a conspiracy-theory direction.

I guess the Wuhan Institute of Virology also produced a special deer-adapted version which they released into the wilds of North America, and a mink-adapted version they released on farms in Denmark, and a hamster-adapted version, and a cat-adapted version, and on and on. Both SARS and SARS-CoV-2 have shown an ability to infect a range of different species.