Is Omicron outcompeting Delta in the UK?

Some mixed messages regarding what might be happening with the two dominant strains in the UK.

On one hand, Omicron appears to be winning in most countries. It now accounts for 100% of cases in South Africa and it is growing rapidly in other countries and on other continents. Graph below shows an increase in delta share over 2-3 months between March and July 2021 and its rapid replacement by omicron in November 2021 – note different time scales:

However, the latest data from the UK government suggest a slowdown in how the proportion of omicron grows, but this could be a temporary respite or a data problem (the number of samples is low):

This shows omicron (black circles; Cases with confirmed SGTF – S gene target failure) and delta (open circles; Cases with confirmed S-gene).

Depending on the point of view, it could be good news – a highly infectious omicron variant being outcompeted by delta, or bad news – as delta is potentially more severe.

We shall see in the next few days where the trajectory goes.