Pushkin.

We will have a test, track and trace operation that will be world-leading.

That's Boris Johnson, the British Prime Minister, speaking to Parliament with a typical

jingoistic flourish in May 2020.

The UK, he promised, would have a world-beating contact tracing system within a few days.

The first wave of the pandemic was slowly receding, but the cost had been brutal.

That spring, the country had suffered one of the deadliest outbreaks of Covid anywhere

in the world, and so the British Prime Minister decided to cheer up the nation as only

he could, by boasting of a contact tracing system that would be better than anything Johnny

Foriner would have.

A contact tracing system for Covid has three key elements.

First, you need to be able to identify who is infected and isolate them.

Then, you need to trace the recent contacts of the infected person.

Finally, you need to be able to persuade those contacts to isolate themselves as well to

avoid any further spread.

It's not easy.

But if you get it right, you can keep the virus contained, while allowing everyone else

to relax a little and go about their lives.

Taiwan managed this, so did South Korea, and Vietnam, and Japan.

Anyway, the UK system didn't need to beat the world, just needed to beat the virus.

In the summer of 2020, there seemed to be every chance of doing that.

Infections had been beaten back by a long, strict, and costly lockdown.

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