I dont see this as all that sudden. Here is a quick general history:
In 1976, Ebola (named after the Ebola River in Zaire) first emerged in Sudan and Zaire. The first outbreak of Ebola (Ebola-Sudan) infected over 284 people, with a mortality rate of 53%. A few months later, the second Ebola virus emerged from Yambuku, Zaire, Ebola-Zaire (EBOZ). EBOZ, with the highest mortality rate of any of the Ebola viruses (88%), infected 318 people. Despite the tremendous effort of experienced and dedicated researchers, Ebola’s natural reservoir was never identified. The third strain of Ebola, Ebola Reston (EBOR), was first identified in 1989 when infected monkeys were imported into Reston, Virginia, from Mindanao in the Philippines. Fortunately, the few people who were infected with EBOR (seroconverted) never developed Ebola hemorrhagic fever (EHF). The last known strain of Ebola, Ebola Cote d’Ivoire (EBO-CI) was discovered in 1994 when a female ethologist performing a necropsy on a dead chimpanzee from the Tai Forest, Cote d’Ivoire, accidentally infected herself during the necropsy.
So research and by inference, working on a cure / vaccine has been happening since at least 1990 and perhaps sooner. So, twenty to twenty-five years a small group of people have been working on a cure in one form or another.
You missed Ebola Bundibugyo, which has caused two outbreaks in Uganda. It has a slightly lower CFR than other Ebola strains.
Also, the Cote d’Ivoire was renamed to Tai Forest.
The newest filovirus was found in Spain and is called Lloviu (Lloviu cuevavirus). It has only been known to cause bat disease and death.