Building a hospital takes many years.
If there is a surge in demand, there may not be enough existing space to cope.
However, if you contract your hospital* from BorgCo, you avoid many of the worst problems.
Seen from the outside, the hospital looks like any other. Its only distinguishing feature
is that it is in the centre of a gigantic car park, ten times larger than the area of the buildings.
The car parks look fairly standard, too. But on close scrutiny, it becomes apparent that the street furniture - lamp poles, signage, traffic islands - seem unnecessarily lavish.
Why is that, you ask ?
Well, all those normally unregarded bits of infrastructure contain access points for hospital services, networked under the paving. Water, effluent, electrical power, compressed air, data links, fuel gas, oxygen ... sealed away inside plinths and pedestals.
Should an emergency arise, a standard container can be placed on a pad, from which is unpacked a tent and all the hardware needed to attach to the connection points to provide heating and lighting. The container itself has the electrical distribution panel and monitoring, possibly some HVAC too, built in. There are recessed tiedown/anchor points embedded in the roadways so the lightweight tentage can be firmly secured against wind. Add some flooring and a few folding beds, et viola ! A ward, ready to receive patients.
When the panic is over, the kit is thoroughly disinfected and packed back into its container for "next time", and the car park can go back to be a place for parking cars ...
Extra containers hold add-on kits for special functions allowing any standard tent to be equipped for something more than patient storage.
Yes, the military have this already - the portable, modular parts, anyway - the innovation is the pre-configured paved area ready for fast setup. Putting the services in at build time saves a lot of messing around and expense later.
And if you want to permanently expand the facility, you already own the land, and the buried*** services are ready to go.
*As in "sign a commercial contract", not "contract a condition by transmission of an infective agent". It is not possible, so far as is known** to become infected with hospitals, altho it is extremely common to become infected IN hospitals. The analogy is exact; doctors circulate through hospitals like white cells in blood, killing off the patients who infect it, disrupting the smooth running of the paperwork and worse interfering with opportunities to play golf. They even wear white coats to identify themselves, adding insult to injury (or more accurately lethality)
**It is possible to become a bed-sitting room, however, <link>
*** As piped fuel gas is available through the upstands, one of the modules is a cremator unit, if you don't want to bury the results of the medic's endeavours ... graveyards right next to hospitals are not appreciated by patients....