“Can you rule out a laboratory escape? The answer in this case is probably not.” page 
>This is the period in the story that demands a very close investigation, when chimeric assemblages may have been created and serially passaged, using BtCoV/4991, a.k.a. RaTG13, and other bat viruses, perhaps along with forms of the human virus. It’s when Shi and Baric both published papers that were about what happened when you hot-swapped mutant spike proteins between bat viruses and human viruses.
Also, see
- Tracking Down Covid-19 Origin
- South African N501Y mutation page