Some 51.8% of a sample of new coronavirus cases in London with specimen dates for December 11 and 12 were found to have S gene target failure (SGTF) – a way of detecting the likely presence of Omicron.
Most samples of Omicron that have been sequenced in a laboratory have been found to contain a slight but identifiable difference from other Covid-19 variants such as Delta.
This difference – a deletion in the S gene – shows up in certain laboratory PCR tests and can be used as way of estimating the spread of Omicron.
Of the 1,391 Covid-19 cases in London recorded on December 11 and 12 where the S gene status could be determined, 721 were classed as SGTF.
The figures, which have been published by the UK Health Security Agency, also show that 26.9% of a sample of detectable cases in eastern England from December 11 and 12 were classed as SGTF, along with 25.4% in south-east England and 20.8% in north-west England.
Levels were lower in all other regions, with north-east England having the lowest estimate of 6.2%.
The level for the whole of England was estimated at 24.0%.
