I'm wondering what all the differences are and how much benefit you really get from a Field Hospital to see if its worth it compared to a rank 2 or rank 3 Infirmary.
A Field hospital is the same as a rank 3 Infirmary in nearly every aspect, but the Field Hospital provides the following bonuses.
The first difference we can note here is the building cost.
- To reach rank 3 Infirmary: 19 materials and 15 chemicals
- To build a Field Hospital: 10 materials and 5 chemicals
The Field Hospital can craft everything a rank 3 Infirmary can at the same cost, but a Field Hospital will require fewer plague samples to craft the Blood Plague cure. 4 instead of 5.
Active treatments are the same, except that a Field Hospital also provides a more global healing towards your community.
Infection Therapy (8 meds)
- remove all infection from all survivors
Physical Therapy (8 meds)
- remove all injuries and trauma from all survivors
The last difference between the 2 is that a Field Hospital also gives you a permanent +10 health to all your survivors.
Both facilities also provide passive healing to survivors that are "resting".
So basically a field hospital allows your community members who have trauma or injuries to heal while not playing as them. Basically passive healing.