I talked to my avian vet about vaccinating. We have a lot of wild birds in our barn--a LOT, there's no front door on the barn (there is a door on the section that holds the chickens) and the vents haven't been repaired in, uh, ever. So the barn is really chock-full of sparrows, mourning doves, everything. And my chickens are undoubtedly going to contact these wild birds. Also, the previous owners for the past couple hundred years have all had chickens in this barn, and heaven knows what those chickens had for diseases. So we went over the available vaccines for diseases in the area, how long those diseases last in an unheated barn without chickens in, and what I was willing to do--vaccines in the water with an eyedropper, no problem, but vaccines that have to be stabbed into wing-pits with a large-bore needle, forget it.
Because of the history of the barn and the number of wild birds in my yard, we decided to give as many vaccines as possible, almost as many as a commercial flock would receive. They will also continue to receive medicated feed for the next few weeks until they are acclimated to their new home. Yep, that means I buy expensive vaccines, mix them up, use about 1/4 teaspoon of the vial and throw the rest away. But I would rather do that than lose my flock due to a recurring disease hanging out in the barn or in a wild bird. There's no way to adequately disinfect wood, so it's not like I can keep them safe with good hygiene alone.
Just my opinion. You are in the city, your birdies probably will not meet many wild birds, and it depends on how you are housing them--in an eglu type of hutch, or a brand-new pen made of easily cleaned materials (concrete floor or some such), I would not worry about it.
