New character types, mainly
Fringefolk: Holy shit! All those years spent studying things no-one else cared about, like off-the-grid water filtration systems, or heritage gardening, or forging metal, or weaving or whatever? Suddenly worth a prime place in the warm and dry. Your world's been upended, socially, but the rest sort of makes sense now.
Medic: People always get sick, or hurt, and need help, no matter what the rest of the world looks like. Now's no exception, but you've got to get back to basics - that, and hope there's another unraided pharmacy you can find before your stash of painkillers and penicillin runs out.
Familyman: You made it through the first shock, and then you reached out to the neighbors. lately, a few strays have started showing up. Together, you can make a stand, fight back, hold things down. You're not leaving your home, and that's final.