A new COVID variant is spreading across the UK, according to the UK Health Security Agency (UKHSA) - and already makes up one in seven new cases.
Scientifically known as EG.5.1, it is descended from the Omicron variant of COVID.
The UKHSA has been monitoring its prevalence in the country due to increasing cases internationally, particularly in Asia, and it was classified as a variant here on 31 July.
In the week beginning 10 July, one in nine cases were down to the variant.
The latest data suggests it now accounts for 14.6% of cases - the second most prevalent in the UK.
It appears to be spreading quickly and could be one reason why there has been a recent rise in cases and hospitalisations.
COVID-19 rates have continued to increase - up from 3.7% of 4,403 respiratory cases last week to 5.4% of 4,396 this week.
The latest data also shows the COVID-19 hospital admission rate was 1.97 per 100,000 population, an increase from 1.17 per 100,000 in the previous UKHSA report.
Officials say they are "closely" monitoring the situation as COVID case rates continue to rise.
"We have also seen a small rise in hospital admission rates in most age groups, particularly among the elderly," said Dr Mary Ramsay, head of immunisation at the UKHSA.
"Overall levels of admission still remain extremely low and we are not currently seeing a similar increase in ICU admissions.
"We will continue to monitor these rates closely."
The Arcturus XBB.1.16 variant - another descendant of Omicron - is the most dominant, UKHSA figures show. It makes up 39.4% of all cases.
The World Health Organisation (WHO) started tracking the EG.5.1 variant just over two weeks ago.
WHO director-general Tedros Adhanom Ghebreyesus said though people are better protected by vaccines and prior infection, countries should not let down their guard.
"WHO continues to advise people at high risk to wear a mask in crowded places, to get boosters when recommended, and to ensure adequate ventilation indoors," he said.
"And we urge governments to maintain and not dismantle the systems they built for COVID-19."