@S14 I certainly understand your housekeeper's concerns, but maybe you could put together some scientific information for her that might ease her mind. If you simply leave the unit unoccupied for a week, there won't be anything in there that she can get infected from. The virus only lives for about 3 days on hard surfaces like metal, and only for a few hours on soft furnishings. So a week should be more than plenty. (It has been shown to live for up to 27 days in some circumstances, but that's uncommon and depends on on a certain temperature and humidity level, as far as I've read) Then try to get a health-care worker who'll be there for the long haul, and let them know they'll have to look after their own cleaning while in residence. Of course if your normal cleaner simply refuses even if given the facts re cleaning during COVID , you just have to respect that.
If you do manage to get her or someone else to clean, remove all extraneous stuff from the unit, so there is less to deal with. Things like throw pillows, throw rugs, lots of extra towels, decorative items, whatever isn't really essential to whoever might stay there. Leave them plenty of cleaning products. I doubt the health care workers will be spending much time at home anyway- they just need a place to lay their exhausted bodies down and sleep before heading off to the battlegrounds again.