COVID-related hospital admissions have doubled in England in the past two weeks, new NHS data shows.
Hospital admissions over a seven-day average in England were up to 1,129 for the week ending on 30 September.
This was up from 574 two weeks before, and up 33% from the week before.
The number of people in hospital beds in England with COVID is up 87% in the past two weeks.
Dr Susan Hopkins, chief medical adviser at the UK Health Security Agency (UKHSA), said the latest increases were "concerning", and that cases and hospitalisation rates were at their "highest level in months."
"Outbreaks in hospitals and care homes also on the rise," she said.
Independent Sage's Professor Christina Pagel said both admissions where COVID is the primary issue and where it is a secondary issue are rising fast.
She said this pointed to a rise in infections both in the community and in hospitals.
Pagel said we were now in another COVID wave, which was "very bad timing for the NHS where things are already terrible.
"Get boosted if you can wear a mask in crowded indoor spaces if possible and open windows."
The news comes as the latest stats on long COVID show more than one million people in the UK likely suffered their initial infection more than a year ago.
A total of 2.3 million people across the country are now estimated to be suffering from long COVID, or 3.5% of the population.
The figures from the Office for National Statistics (ONS) are based on self-reported long COVID from a sample of people in the four weeks to 3 September.
They show that of the 2.3 million people estimated to have long COVID, 1.1 million (46% of the total) first had COVID-19, or suspected they had the virus, at least 12 months ago.
Some 514,000 (22%) first had COVID at least two years previously.
The data reveals a huge disparity in age groups, with one in 20 (5%) 35-69 year olds in the UK suffering from long COVID, whereas just 2.9% of over 70s reported the same.
People working in social care reported the highest prevalence of long COVID among employment groups (5.5%), followed by civil servants and local government staff (5.2%) and healthcare employees and teachers (5.0%).
Levels were lower among occupations such as financial services (3.4%), hospitality (3.5%) and information technology (3.8%).
The ONS estimated long COVID was impacting the daily lives of 1.6 million people, with 342,000 saying their ability to undertake day-to-day activities has been "limited a lot".
Fatigue is the most common symptom (experienced by 69% of those with long COVID), followed by difficulty concentrating (45%), shortness of breath (42%) and muscle ache (40%).