The US does have the ability to set up large quarantine hospitals on the fly, but they are in tents. These are the same type of military tents that were/are used for migrant internment on the border.

I'm struggling to find a name for the group that I participated in an exercise with, but in my volunteer Search and Rescue days I was a 'victim' for a practice exercise of deploying a tent hospital for a combined human and animal pandemic.

The ability to set up these hospitals is there, what isn't there is the skilled nursing staff for ICU patients, or ventilators for patients who needed them. I'm really not sure how China handled that portion of caring for those that fell ill.