Ebola and SARS were both effectively contained by a speedy medical response. SARS 1 and Ebola have quick presenting serious symptoms reducing their transmission rates. People know they have it early so infect less people. Ebola is still a concern by the way, it has been for decades, there’s just not an active outbreak right now.
The previous SARS virus infected less than 10,000 people worldwide, it’s currently believed that many people already have this virus in the UK alone. That’s why this virus is such a threat. More people have it which means while the death rate is lower the overall numbers of dead will be much higher.