Sorry about Valkyrie Scott. My dog Val had had a puppy shot, but caught parvo anyway. I took her to my vet then dropped her to a daughter and my exhusband to dose with antibiotics while I vaccinated the rest of my dogs with feed store shots, and the neighbor's dogs too. ($10 and hold em still is easy). Val recovered, no one else got parvo. Then she got her rabies shot and her fur fell out. She had an immune disorder, demodex mites. Vet wanted $900 to treat them. I got some mite dip, and some probiotics, and kept her out of the sun til her fur grew back. Waited to spay her, vet said she might not make it to a year, but she did, and at 1 year got spayed and did live a normal life. It's a genetic disorder that does strike now and then. Funny thing, no way was she exposed to parvo. It had been 6 weeks since her puppy shot, she was overdue for the next one, and very few dogs out here. Unless the coyotes have parvo.
But it happens. Sorry for your loss. But I wouldn't give up on vaccines.