Exponential growth

Health officials say the number of people expected to contract the virus from each person who has already contracted it – the ‘reproduction number’ – is currently at epidemic levels of 1.5-2, and the outbreak won’t decline until it falls below one. CDC Director Frieden:

The speed at which things are moving on the ground, it’s hard for people to get their minds around. People don’t understand the concept of exponential growth

WHO assistant director general Bruce Aylward describes the situation in west Africa:

The situation is worse than it was 12 days ago. It’s entrenched in the capitals. Seventy percent of the people [who become infected] are definitely dying from this disease, and it is accelerating in almost all settings