When we were taught about canine parvovirus at college, we were taught that it would normally require a period of hospitalisation at the vets & also isolation because the disease is highly contagious, so I'm surprised that [accepting.change] still has the dog at home. As lil mami said, many dogs die from canine parvovirus - it has a high mortality rate because it is such a hardy virus - even if the dog recovers, it can still carry the virus, and spread it throughout it's surroundings. If the dog becomes too dehydrated, it makes them more susceptible to further infections which doesnt help, thus the need for urgent veterinary care. If the dog has had any diarrhoea or vomiting because of the virus, then the rooms where this has happened need to be disinfected with a strong bleach because of how contagious & hardy the virus is to prevent repeat infection.
I don't think [accepting.change] should be trying to feed the dog, he won't take it because he is too ill for his intestines to be able to cope, which is why the dog would be vomiting food back up, and also why fluids will need to be given via IV as opposed to orally. Please take your dog back to the vets.