My own son is 7 and I have to agree that many kids I think pick up on the fact that something bad is happening.
He has a very good understanding of what’s happening though I’ve had to try to put some of the fearmongering to rest from what he’s picked up from the news. He did get quite melancholy and started thinking a lot to himself and talking about stuff, after a period beforehand of denial that anything was happening until he started reading more and hearing more etc.
I think the best thing to do while still being cautious and ensuring guidelines are being followed is to talk about the future and what you will do when all this is over. While the future is uncertain, to try to give some kind of positivity to focus on both for yourself and your child, it does give that bit of escapism for a while as well as the realization that for many of us this has been a wakeup call and many things we once took for granted are maybe questioned as well as the realization of what and who is important.
As Hevva said above, kids pick up on everything especially younger ones as the non-verbal communication will be amplified so I think she’s right that to try and ensure that you are in a good place would be a very good starting point. If your child sees that you are ok, they are more likely to feel ok.