I don't think they do know totally yet. Scientists won't say until they are 200% sure and the media will grab whichever makes the best headline.
I think posting here with worries is fine as long as it isn't the instant doom that you get on other threads. At least I hope so because I had a wobble about it too this morning but I think the thing with this thread is that it attracts the positive people and we help each other when everything feels hard. There's a big difference between 'I feel worried' and 'sorry, I'm afraid nothing is ever going to get any better and will almost certainly get much worse, unfortunately'