https://www.who.int/health-topics/coronavirus/origins-of-the...
Origins of the SARS-CoV-2 virus
And unlike the arrticle here, this report is based upon interviews with employees at the lab and various form of documentation provided by the lab. Including health records of the employees.
For more from one of the WHO people:
https://theconversation.com/i-was-the-australian-doctor-on-t...
I was the Australian doctor on the WHO’s COVID-19 mission to China. Here’s what we found about the origins of the coronavirus
> We visited the Wuhan Institute of Virology, which is an impressive research facility, and looks to be run well, with due regard to staff health. We spoke to the scientists there. We heard that scientists’ blood samples, which are routinely taken and stored, were tested for signs they had been infected. No evidence of antibodies to the coronavirus was found. We looked at their biosecurity audits. No evidence.
So this is what they were told, but did they actually test the samples, and confirm that they belonged to the right people and originated from the given date? Apparently no.
> We looked at the closest virus to SARS-CoV-2 they were working on — the virus RaTG13 — which had been detected in caves in southern China where some miners had died seven years previously. But all the scientists had was a genetic sequence for this virus. They hadn’t managed to grow it in culture.
This is probably the most convincing argument: if they actually had worked on viruses similar enough to plausible be modified into SARS-CoV-2, this would have left evidence in scientific papers etc.
> While viruses certainly do escape from laboratories, this is rare. So, we concluded it was extremely unlikely this had happened in Wuhan.
This is incredibly weak: "lab escapes are rare, so it's extremely unlikely" is not much of an argument.
> The prior probability of a lab escape is low
but the prior probability of "a pandemic from natural causes envelops the world" is also low, say below 1% a year. But now, given that "a pandemic does envelop the world", the posterior probability of lab escape and natural cause of course rises dramatically... and then saying "we didn't see much evidence for it" on a superficial tour organised by those responsible for the lab does not strike me as a very powerful rebuttal.
It's akin to "the prior probability of labour camps is low", and "on our tour of North Korea (accompanied by several North Korean tour guides showing us just those places they wanted to show us when they wanted to show us) we didn't see any labour camps, therefore we conclude that the probability of labour camps in North Korea is low".
While we're invoking statistics: Take the null H_0 = "the virus emerged naturally in any large Chinese city with > 1m inhabitants". In 2017, there were 102 of those. Thus, the probability under H_0 that the virus emerged in the one city in China with a level 4 biolab has p < 0.01.
It is akin to saying "Pliny the Younger didn't die in Pompeii overtaken by a volcano because there is so many other cities he could have died in and other causes of death." Statistically, that would have been true, up until we learned that it happened. Then the low probability ceases to matter, since it becomes an observation.
Statistically, this is due to both priors rising, proportional to their original values, such that now the sum P(lab escape)+P(natural cause) == 1 and their average is a coin-toss (50-50). So without outside information, the prior statistical probability isn't low: it is exactly neutral between the options.
We've also seen viruses arise in small villages. This is even more unlikely to be predictable in advance which village with p << 0.0001.