I am very sorry for your loss - and yes I have lost kittens to this, both the wet form and the dry form.

Getting a kitten neutered so soon after moving house was not a good idea and I am surprised your vet didn't warn you about that - it's not as if there was any hurry. This isn't your fault though, you were not to know, and if the kitten had been corona-negative this would not have happened anyway.

You could try to get your existing cats down to zero titre before introducing another but you can't guarantee that any kitten you introduce will not be corona positive. If it were me, I would go ahead and get another, but just think this time about minimising stress.

Liz