ITV News Political Correspondent Shehab Khan assesses whether or not the public should be worried about the Delta variant
The variant is believed to have overtaken the Alpha variant, which was previously known as the Kent variant, rising by 5,472 cases since last week to 12,431.
There is also early evidence to suggest there is a "significantly increased risk of hospitalisation" from the Delta variant in comparison to the Alpha strain.
It comes as two studies find that it leads to more severe disease "within 14 days of a positive test". However experts have said more data is needed to confirm this finding.
This week, 278 people with the Delta variant attended A&E, with 94 people being admitted to hospital overnight. This compares with 201 A&E attendances in the previous week, with 43 admissions.
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The majority of admissions continue to be people who have not been vaccinated, PHE said.
PHE figures show that from February 1 to May 31, there were 9,427 cases of the Delta variant recorded in England, of which 5,172 were in unvaccinated people.
Bolton continues to be the most affected area where cases of the strain have risen by 795 to 2,149 but officials have said there are "encouraging signs" that the transmission rate is falling here.
In Bedford there have now been 608 confirmed cases, with 349 in Leicester, 278 in Manchester and 223 in Birmingham.
There were also 140 outbreaks of the Delta variant in schools and 62 in workplaces between January 4 and June 1.
PHE also said outbreaks of the Delta variant in schools are at low levels, but added that there has been a slight increase in these cases over recent weeks - similar to its circulation in wider communities.
The latest PHE data suggests there have been 97 confirmed Covid outbreaks in primary and secondary schools that have had at least one variant case linked to them over the most recent four-week period.
This is the equivalent of around one in 250 schools.
Dr Jenny Harries, Chief Executive of the UK Health Security Agency, said: "With this variant now dominant across the UK, it remains vital that we all continue to exercise as much caution as possible.
"The way to tackle variants is to tackle the transmission of Covid-19 as a whole.
"Work from home where you can, and practice ‘hands, face, space, fresh air’ at all times."
Transport Secretary Grant Shapps also cited concerns about a new mutation of the variant which first originated in Nepal - which was a key reason for moving Portugal from green to amber on the travel destination list from England.