@Heather133,
For clarification, is the person who tested positive listed as one of the guests in the reservation? I unsure, because your post reads like the infected person is a visitor of the registered guest. If the registered guest isn't the person with the positive result, and it also seems like they've not been in recent physical contact with each other, I don't understand why a full refund would be warranted.
@Colleen253,
To me it seems like the Airbnb team is actually applying some due diligence in accessing if the cancellation meets the extenuating circumstances criteria, and haven't told the guest to cancel yet, because doing so may infer that the guest will get a refund. I had a guest cancel two days before their Christmas day arrival and requested a refund due to a positive test result from the prior week. I contacted Airbnb CS, and they in turn reached out to the guest. I don't know what transpired other than the guest canceled the reservation, and I was paid for the stay.