There is suppose to be a defined rate of how it will spread. I don’t know that algorithm. What is different here is that in West Africa they quarantine (I know politically incorrect) the infection zone and the virus cannot find a new host after it burns out. We cannot do that here.
Well that has worked in the past, we may have moved into a different pattern now. It's going to come down to how easily it is transmitted. How lone it lives on hard surfaces.