The prevalence of the Omicron variant across the Anglia region doubled in the run-up to the festive period with cases hitting more than 75,000.
Analysis of positive Covid tests by the Wellcome Sanger Institute in Cambridge suggested there were 75,245 cases involving the Omicron variant in the seven days to Christmas Day.
That compared to 37,880 cases in the previous week - an increase of 99%.
The figures are estimates based on analysis of 60,000 test samples processed every week at the Sanger Institute labs. It takes additional time to analyse and genetically sequence the positive tests so there is a time lag in the publication of these figures compared with the daily data issued on the government's coronavirus dashboard.
There was a record daily number of confirmed coronavirus cases in the Anglia region on Wednesday 29 December with nearly 25,000 positive tests. That would have included all variants of the virus including Delta.
The analysis of the test samples at the Sanger Institute highlights how rapidly the Omicron variant spread across the Anglia region since the first positive cases were identified in the UK in Brentwood in Essex and in Nottingham at the end of November 2021.
There were an estimated 4,700 Omicron cases in the Anglia region in the week to 11 December. That had increased 15-fold within a fortnight spreading to all areas in the East of England.
Although the Omicron strain of the coronavirus is much more transmissible than the original variant, early research has suggested that it triggers a less severe illness in most people. However the sheer numbers of people being infected has seen greater numbers of patients being treated in the region's hospitals with Covid.
On Monday 3 January 2022, there were 1,250 patients with coronavirus in hospitals in the East of England - the highest number since late February 2021. That was 55% more than the previous week.
In the region, more than 3.5 million people have received three doses of the coronavirus vaccine, representing an estimated two-thirds of adults in the East of England. The roll-out of the booster vaccine has taken place in little more than three months.
The Sanger Institute at Hinxton near Cambridge is contracted by the UK Health Security Agency to sequence coronavirus genomes so they can identify and track new variants of the virus.
Find out more about the coronavirus data in the ITV Anglia region
The ITV Anglia region consists of the East of England counties of Bedfordshire, Cambridgeshire, Essex, Hertfordshire, Norfolk and Suffolk along with Milton Keynes, Rutland and Northamptonshire.