With that said, the Wuhan lab had both BSL-2 and BSL-3 units studying bat coronaviruses before the pandemic [1]. After the COVID pandemic hit the PRC mandated all COVID research be carried out in BSL-3+ conditions; the research they're doing at the moment on COVID happens to be done in their BSL-4 facility but only because of lack of sufficient resources in their BSL-3 facility; that's likely temporary [2].
I'm not sure why a secondary leak after a pandemic already began would be just fine though.
> With that said, the Wuhan lab had both BSL-2 and BSL-3 units studying bat coronaviruses before the pandemic [1].
That's interesting indeed. Thanks.
> I mean, none of them should leak.
In theory, there's no difference between theory and practice. In practice there is.
BSL-3 shouldn't leak, yet we don't put super scary viruses in there, because we know the probability it could happen isn't that low.
> I'm not sure why a secondary leak after a pandemic already began would be just fine though.
Fine isn't the word. It's still an industrial accident, but not necessarily a catastrophe. Do we even have an example of such leak that would have triggered an epidemic in the vicinity of the lab?
That's not easy to say. "Leaking" can be as simple as a researcher catching COVID outside the lab and then spreading it to a coworker who then spreads it outside the lab.
