COVID-19 infection levels are rising and more people aged 18-44 are catching it than the elderly, new figures suggest.
Around 2.5 million people, or one in 24 in England and Scotland, are likely to have tested positive for the illness on 13 December.
That equates to around 4.2% of people in private households across the two nations.
It’s a rise from 2%, or one in 50, at the start of the month and 1.5%, or one in 66, on 14 November.
London and the South East are the worst-affected regions.
The data comes from the new winter COVID-19 infection study, which will monitor the spread of the virus during the next few months.
It is a smaller version of the UK-wide infection survey that provided weekly updates on the spread of the virus for nearly three years during the pandemic and afterwards.
The new study, run by the Office for National Statistics (ONS) and the UK Health Security Agency (UKHSA), will publish estimates every fortnight.
It is based on data collected from around 150,000 individuals and focuses on just England and Scotland, rather than the whole of the UK.
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Those taking part use lateral flow devices to test for the virus and then report the results to the ONS, with each person asked to test once a month during a scheduled seven-day period.
Professor Steven Riley, UKHSA director-general for data and surveillance, said: “At this time of year, the cold weather, shorter days and increased socialising mean that the potential for transmission of respiratory viruses like COVID-19 is particularly high.
“This, as well as the possible impact of new variants, means it’s not unexpected to see cases increasing.
“If you are showing symptoms of COVID-19 or other respiratory illnesses, you should try to limit your contact with other people as much as possible, especially those who are older or more vulnerable.”
Estimates of infection levels in the new study cannot be compared with figures from the previous survey, because the two studies use different methods of testing and compiling the data.
More than 233,000 people in the UK have died from COVID, putting it sixth in the global list, compiled by the World Health Organisation.
The US, with more than 1.1 million, has had the most virus-related deaths.