The numbers rely on the mathematical concept of exponential growth.
And without drastic action, cases could double every five or six days.
The consistent doubling of cases in a fixed period is the hallmark of exponential growth.
This number is key todetermining how widespreada disease will become.
For COVID-19, early estimates of the basic reproduction number have itsomewhere between 1.5 and 4.
The infographic assumes a figure somewhere in the middle, at 2.5 infectious contacts per infectious individual.
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The revised infographic below shows the number of currently infected people.
However, the basic reproduction number of the current stage of the outbreak is way above one.
What exponential growth is
But what, precisely, is exponential growth?
This means that as the quantity increases so does that rate at which it grows.
The total number of confirmed cases of COVID-19 in the UK is increasing exponentially.
In a pyramid scheme, each new investor invites two more recruits who in turn invite two more.
When the pyramid tumbles, most investors lose their money.
The surrender of Imperial Japan was announced nine days later.
This is the awesome power of exponential growth.
Exponential is oftenused as a byword for rapid or large.
As a counterpoint, consider the money in your bank account.
If you could wait long enough, even the smallest investment would become a fortune.
But dont lock up your rainy-day fund just yet.
Very few people would accuse the exponential growth associated with their bank account of being large or rapid.
So exponential growth does not necessarily deal with big quantities, and it is not necessarily fast.
Small comfort
One small crumb of comfort is that almost nothing can grow exponentially forever.
