John Gruber at Daring Fireball posted about The Lab-Leak Hypothesis with a link to an article in New York magazine by Nicholson Baker. That piece is freely available at the link but I found our local library has the magazine online and read it there. It’s well worth the time to read it.
The article presents strong evidence that the coronavirus responsible for the COVID-19 pandemic does not have a zoonotic origin; that is it did not arise naturally from animals. That said, neither did it result from a deliberate act (of bio-terrorism or bio-warfare). Rather, the most likely source was a laboratory leak or accident.
The closest match to the novel coronavirus (96% similarity) is a virus, RaTG13, found in a bat from southern China, about 1500 km from Wuhan. That species of bat is unlikely to have spontaneously travelled to Wuhan and the market there was not selling bats. However, Wuhan is the site of the only Level 4 biosecure laboratory in China and researchers there were working with the RaTG13 virus. A simple breach of protocols could have resulted in the initial infection.
Exposure to the original bat virus might not have been a problem but scientists at multiple locations around the world, including several laboratories in the USA and the one in Wuhan, have been experimenting with cross-species transmission of viruses. Their work is intended to demonstrate the potential for such transmission and prepare strategies for rapid response to any such incident. They have been working on making animal viruses infective to humans in order to provide targets for testing the development of effective vaccines. There is a logic to that work but it is inevitably dangerous if something goes wrong.
Scientists in the USA have been cooperating with scientists in Wuhan through the exchange of genetic information and samples. There has also been a substantial flow of funding from the USA to support the work in Wuhan.
There is no direct evidence that the COVID-19 pandemic resulted from an accidental breach of laboratory protocols in Wuhan or that a series of natural mutations caused a bat virus to become infective for humans. Both are possible but having read the article, one hypothesis seems inherently more plausible than the other. The dreadful irony is that US funding intended to prepare science for a more rapid and effective response to a viral pandemic may have contributed to the emergence of a pandemic to which the US response has been notably ineffective.