I live in Southern Oregon and have never vaccinated for Potomac, but I am going to begin next spring.
Late last summer, one of my horses had to be hospitalized in horse ICU for 8 days, IV's running, etc. because of a very nasty diarrhea. Over the period of hospitalization, tests for chlostridium, salmonella and Potomas Horse Fever all came back negative. They had begun treatment for both salmonella and potomac immediately because that was how he presented.
The horse survived. My savings account took a major hit. I talked to the treating veterinarian and my usual equine man, and they both said that there was some question about the efficacy of the PHF vaccine, but then one doc asked me if I kept fire insurance on my house.
I'm going to go ahead and vaccinate. I'd be in trouble if we had very many vet bills that large.
