I have had to treat an outbreak of fowl pox in one of my flocks. It has been a nightmare, although I am happy to report that there have been no fatalities (yet). I did take one hen into an avian vet because her eyes were swollen closed and she began spitting the food out that I had been forcing into her. I am now tube feeding her.
None of my chickens had any vaccines but I have since purchased the fowl pox vaccine to administer to the other two flocks that I have. The vet said that fowl pox is common in my area.
If you can find out what the typical ailments are in your area, you might want to vaccinate for those things.
When I read up on fowl pox, it said that it was typically not deadly. But, upon further reading, I found out that chickens often die from secondary complications due to the pox. If I had not been at home full time to feed and treat my birds, there is no question that I would have lost some. I may still loose the hen that I'm treating now. She has wet and dry pox and is in very bad shape, regardless of the attention she is getting.
I am trying to gather the nerve to give the vaccine. I've never give any before, but I know now that the vaccine will hurt us a whole lot less than what we've been going through for a month now.