True. Even those who get a yearly influenza virus vaccine get it. Much of it has to do with the strength of an individual's immune system. That's why the young and old are the most to succumb to the flu - shot or not.
Plus, I tend to agree with a post above that possibly many Africans have developed somewhat immunity to the ebola virus over decades of exposure. However, that raises the question why are they dying in the thousands now? Has it mutated and become stronger and airborne by simply breathing? I'm not talking about a sneeze which is actually a particle of body liquids.
If this thing has mutated, we're looking at a world pandemic. So why import more from the ground zero countries?
First outbreak in cities. They didn't control well, especially the bodies. If it were airborne then about 50% of the residents of the West Point slum would be dead today along with the reporters who were there. That would be repeated elsewhere. We would see thousands turn into millions within a few weeks. Instead it seems to be the case that the primary spread is by people carting around other dying and dead people in taxis. Burial is still ad hoc in some cases. Hospitals are overwhelmed. Ebola centers are full. It is a disaster yet the infect rate is 100 cases a day in each country (reported and unreported) out of millions of people.