Health officials tested a sample of new Covid cases over two days earlier this week, to see how many cases had what is known as an S-gene dropout, or no S gene.
Delta does not have an S-gene dropout, so that gives a clue that it could be the new variant. But not all S-gene dropouts will necessarily be Omicron and full genomic sequencing is needed to be sure.
The UKHSA said 54.2% of cases tested had the S-gene dropout suggesting it was Omicron. Across the regions the figure was:
- East Midlands: 51%
- East of England: 62%
- London: 80.8%
- North East: 26.5%
- North West: 52.6%
- South East: 55.9%
- South West: 48.2%
- West Midlands: 45.7%
- Yorkshire and Humber: 46%
However
all figures are only based on samples tested at four of the UK Lighthouse laboratories - Alderley Park, Glasgow, Milton Keynes and Newcastle - which means there are likely to be parts of the country where the prevalence of Omicron is under-reported.