This is a very lengthy and well-researched story that basically just says "we don't know but could be". Which I think is where we've been for the past few months. There was a lot of whiplash early on between conspiracy theorists trying to peg this as a biological weapon attack and scientists trying to stick to the evidence. McNeil does a really thorough job dissecting the mess of nonsense and looking at evidence. But the result is still that we don't know. And probably never will.