# Covid again – the UK mutation

So, there is a new strain, originating in the UK, which is „70% more contagious“. Don’t even ask what that’s supposed to mean. The salient fact is that cases in the UK are on course to double every ten days now, even under lockdown conditions.

Basically, in this figure we see how in October and November the percentage of the new strain amongst sequenced strains rose super-exponentially to reach 10% in mid November. Then the figure mercifully ends.

But here, in number-of-cases figure for a bunch of random countries we see that the exponential kept going up until it burst out of the chest cavity of the UK like an alien. Meaning, that while other strains, aka „normal Covid“, were nicely going down, this strain took over and started dominating the case numbers. Because it is still not even close to 90% of all cases, and because „normal Covid“ is likely still going down, the number of all Covid cases is still not rising with the speed with which „new Covid“ is spreading. In the last three days the number of cases went from 400 to 500 which corresponds roughly to doubling every ten days.

If „new Covid“ is doubling every 6 or 7 days under lockdown conditions … well, let’s calculate some example numbers. Let’s say 300 of the 500 cases per million in the UK on December, 23rd are of the new strain. Of course, Christmas and new lockdown rules will make everything worse or better, but if we just extrapolate, 10 doublings will take just 60-70 days and take the number of cases to 30% of the population.

As of now, in the UK a record number of patients is already being treated for Covid. So frankly, this looks very bad.

Given that the new strain has been spreading for 2,3 month in the UK, it is obvious that it is already everywhere else in Europe and in the US. And in fact is has been detected everywhere people bothered looking for it. How much are we behind? 5 doublings aka a month? This will become clear when local outbreaks just start exploding. The first local exponential can than be used to extrapolate for the whole country. Given the way exponentials work the numbers won’t be horribly off even if you ignore all the other local seeds of the new strain.

Of course Christmas is going to spoil all the data for at least another week probably two. But within a month we will see whether the whole Covid saga will end with a big bang, where just when the vaccines are starting to be doled out, one last big wave gets most of the population anyway.