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ANALYSIS

Why are coronavirus cases rising and what is the significance?

Tom Whipple
The Times

Suppressing a virus is where the goals of public health come into conflict with the laws of mathematics. Public health doctrine tells us that we will not eradicate this coronavirus any time soon: all we can do is manage it at a low level. The problem with this is that mathematics tells us diseases don’t like to stay at a low level.

The spread of a disease doesn’t make a nice flat graph obediently going from one person, to one more person, to one more person. Diseases spread exponentially. They go from one to two, two to four, four to eight.

Fighting this explosion, as we have been trying to do, is an “unstable equilibrium”. It is a little like keeping a ball balanced on