Meet the USNS Comfort, Navy hospital ship that has treated thousands around the world

And mobile

It's definitely not a brick and mortar facility. Many of the "beds" are racks stacked two or three high. Like all of our deployable military medical capacity it is tailored for a patient that is 18-24 years old. They have done very well improvising to ensure the treatment facility meets mission (see the crib folded up along the wall.) That includes how patients are received aboard. The ship was designed to receive patients primarily from the flight deck. They developed a solution for Haiti to receive patients from the sea.
Last thing to remember is that every patient that arrives aboard for care must eventually return from the sea most likely to a medical facility ashore. While a large white vessel with a Red Cross emblazoned on it sends a message of resolve much more work occurs on the ground getting health and medical services back on line. I'm torn whether it's needed in this case or if land based support would be better suited for this mission.