There has been a 14% rise in people testing positive in the week to 20 September - the biggest increase since the summer.
More recent data showing a rise in hospital admissions with Covid has been called “a wake-up call”.
Dr Thomas Waite, deputy chief medical officer for England, told BBC News that a number of new sub-variants of Omicron were circulating at low levels, and could be behind the hospital figures.
Health experts have warned of a flu and Covid “twindemic” this winter, urging those who qualify to get their free jabs now.
Although Covid is increasing in England and Wales, the trend is uncertain in Scotland and Northern Ireland, the ONS says.
In the UK as a whole, it is the first time estimated Covid infections have risen above one million since the end of August 2022.
The tests found that about one in 60 people had Covid in the UK in the week to 20 September, up from one in 70 the week before.
But there were noticeable differences in trends in the four nations of the UK.
The ONS says Covid is infecting:
- one in 65 people in England (up from one in 70)
- one in 50 people in Wales (up from one in 75)
- one in 80 in Northern Ireland (the same as the week before)
- one in 45 in Scotland (up from one in 55)
Data is for the week ending 17 September 2022 for England, and the week ending 20 September 2022 for Wales, Northern Ireland and Scotland.
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