I spent 2 months in Sierra Leone last year and a month working with Wellbody Alliance [1] in the impoverished mining district of Kono. So far that part of Sierra Leone has been spared from the virus but with the limited health resources in that area, it is only a matter of time.
I can personally speak for their effectiveness and tell you that your donations will actually end up in the form of medicine or medical services to someone who really needs them and not in the hands of some giant NGO that ends up swallowing 75% of what you send them for admin costs and first class tickets.