I am neither an expert in virology nor mathematics, but my extrapolation from the case doubling rates is that you are now *12 times* more likely to test positive for the #Coronavirus if you live in Great Britain than if you live in Northern Ireland.

How has this happened?

1/6

Firstly, there is a simple reality that if you live in Great Britain you are now significantly more likely to get tested, so more cases will be picked up.

But higher testing is itself a consequence of higher infection rates. It does not explain all or even most of the gap.

2/6

Then there is sheer geographic fortune.

“Undercover spread” as warned about by @c_drosten affected all but the most peripheral parts of Great Britain but, because travel between the islands was restricted, did not significantly affect the island of Ireland.

3/6

Another bit of good fortune connected to that is probably density of population. A combination of peripherality and rurality has also resulted in low current infection rates in much of the Highlands, West Wales and Cornwall, as across nearly all of Ireland.

4/6

But IMHO it wasn’t all good luck.

The re-introduction of contact tracing a full month before it was operating again elsewhere in the UK helped. It largely did what it was supposed to, and helped identify and block chains of infection in NI in a way that didn’t happen in GB.

5/6

Questions must be asked of all three governments responsible for other jurisdictions in UK re why they were so quick to give up contact tracing and so slow to restore it.

It is surely part of the reason NI is close to elimination while GB infection rates remain so alarming.

6/6