> human hosts

We think it came from some form of animal, and I've seen a report of a low level infection in a dog.

Edit: While I think the former is common knowledge, here is a source for the latter: https://www.cbc.ca/news/health/coronavirus-dog-spread-humans...

Not practical when you do it for a year. And don’t forget the world around you, you gonna miss cases when someone flys in? Or are you gonna block all borders? The question is how long you gonna let economy suffer. Die by virus or die by economic disaster

the lancet published that the amount of time you remain infectious after infected is usually 20 days, but can go as high as 40 days.

I don't think you understand what you are proposing.

I did not hear anything that it is not possible for a human to spread it while not being affected by it.

At least for influenza that's partially the case and going around the globe.