Vaccines have been around for Ebola but it takes time to get them up & going until the safety aspects are known approx Ten years, they are I believe about two years left to complete these checks, also there is I believe more than one strain of this virus which further complicates matters!.
AIDS is still a very nasty & rife disease however if people use the correct method of contraception & hygiene it is preventable, like everything in these poor countries, lack of education, hygiene ,contraception, & the worst of all religion & ignorance will allow this disease to continue !