Hi Ken,
Bummer of a case. Hopefully they won't be asking for vaccines in the future. If they do, refer!
The default diagnosis in many young animals, especially cats and humans, is Qi deficiency. Certainly the picture you present of the cat before this event is one of deficiency - with its weakness and low activity. When Qi drops so low as to produce paralysis, then we have Wei syndrome (atrophy) due to Qi deficiency.
There are two good options for you. The first is Bu Zhong Yi Qi Tang. This is commonly used in China for slightly less severe cases of paralysis, such as most notably myasthenia gravis. I've seen it work well in animals for this condition, too.
For Qi deficiency causing outright quadriplegia (infantile paralysis, in humans), I've used Bu Yang Huan Wu Tang with success. The Jing Tang version won't work, and the typical human form may be a little too heavy in Huang Qi, or Astragalus, but it will still be a better one to use. Mona has one from Evergreen that can get you started, then it can be tweaked to create more balance later, if needed.
The formula should work and won't taste too bad. Let us all know how it goes. I'm sure we all empathize with your situation.
Steve