More than a year after the initial documented cases in Wuhan, the source of SARS-CoV-2 has yet to be identified, and the search for a direct or intermediate host in nature has been so far unsuccessful.
The low binding affinity of SARS-CoV-2 to bat ACE2 studied to date does not support Chiroptera as a direct zoonotic agent. Furthermore, the reliance on pangolin coronavirus receptor binding domain (RBD) similarity to SARS-CoV-2 as evidence for natural zoonotic spillover is flawed, as pangolins are unlikely to play a role in SARS-CoV-2′s origin and recombination is not supported by recent analysis.
At the same time, genomic analyses pointed out that SARS-CoV-2 exhibits multiple peculiar characteristics not found in other Sarbecoviruses.
A novel multibasic furin cleavage site (FCS) confers numerous pathogenetically advantageous capabilities, the existence of which is difficult to explain though natural evolution...
source: https://link.springer.com/article/10.1007/s10311-021-01211-0
I looked into these lab origin theories for the furin cleavage site last year. The problem with it being a laboratory insertion was that although performing an insertion is relatively easy once you know what to insert, generally it’s beyond current science to independently create mutations for a specific purpose.
It’s a bit beyond me as a non-biologist but my feeling based on the literature was that the lab origin was unlikely. However it is pushed in certain circles partly for ideological reasons, based on evidence that is plausible at first glance but with a lot more digging not entirely convincing evidence.
However, there didn’t really seem to be much neutral expert analysis of the evidence.
At the same time, China risks looking guilty because they are defensive and try to control the information. All this leaves this kind of article with a seemingly plausible scientific and ideological basis that is difficult for laymen and even scientific journalists to evaluate due to the complexity of the science involved, and not many scientists interested in spelling out why the reasoning might be flawed.
You also see in the quote from the article:
“Yes, but your wording makes this sound unlikely — viruses are specialists at unusual events,” is the riposte of David L. Robertson, a virologist at the University of Glasgow who regards lab escape as a conspiracy theory.
The transition from arresting doctors to locking down cities doesn’t make much sense otherwise. You could argue they had motivation to arrest doctors talking about a natural infection if they thought they were spreading fear and disrupting lunar new year festivities, but going to locking down whole cities is about as fear inducing and disruptive as it gets. If that were the motivations for arrest, I’d expect more reluctant and less heavy handed mitigation efforts.
If this were a natural disease and the motivations were to control it as quickly as possible, I’d expect early doctors to be painted as national heroes/propagandized positively very early, similarly to the portrayal of the people that built extra hospital spaces early on.
It’s possible there were different officials involved that changed motivations halfway through, but the lab leak hypothesis offers a more consistent explanation. It makes sense that they would have tried to control the virus quietly if it were a lab leak/wanted to keep it secret, and that they would engage in drastic measures to control it when that didn’t work.
No doctors were arrested early on. Few got cold tea lectures about spreading rumors that literal SARs returned not novel SARs like virus. Signed boilerplate paperwork and was released back to work. This is generic behavior for "picking quarrels and provoking trouble" tier infractions. Not particularly heavy handed at all as far as PRC behavior is concerned. Folks get talks with cyber security for far less. Arguably warranted, had covid not been once in generation virus, spreading panic based on rumors to some critical mass before CNY is pretty egregious. The fact these doctors got slap on risk treatment shows officials were essentially oblivious of severity of novel virus. If there was foreknowledge of a lab leak, these doctors would be under surveillance and stashed away in safe house away from family/friends/work for months/years like in other politically sensitive cases.