A total 33,630 new Delta variant cases have been discovered in the past week and new hospital admissions have nearly doubled, Public Health England has revealed.
The figure was an increase of 12% on the 29,892 Delta infections recorded in England in the seven days to June 9, and a 79% rise on the total number of cases of the variant.
In the previous week the case numbers had doubled, with the latest figures a sign the infection rate could be slowing.
However hundreds more people were admitted to hospital in the past week, with new admissions nearly doubling in the seven-day period to 806.
The latest infection numbers take the total number of confirmed cases to 75,953, PHE said on Friday.
The Delta variant now comprises 91% of sequenced cases, PHE said, adding that vaccines remained effective at providing protection against risk of hospitalisation with the virus.
Boris Johnson delayed 'Freedom Day' for another month over concern at the rate of the strain's spread, with new Covid hotspots emerging in England's North West in particular.
The fourth and final phased of his roadmap out of lockdown was shifted from June 21 to July 19, to give vaccinators more time to double-jab as many older adults as possible.
A total of 806 people in England have been admitted to hospital with the Delta variant as of June 14, a rise of 423 on the previous week, according to new figures from Public Health England.
Of the 806, 527 (65%) were unvaccinated, 135 (17%) were more than 21 days after their first dose of vaccine, and 84 (10%) were more than 14 days after their second dose.
As of June 14, there have been 73 deaths in England of people who were confirmed as having the Delta variant and who died within 28 days of a positive test.
Of this number, 34 (47%) were unvaccinated, 10 (14%) were more than 21 days after their first dose of vaccine and 26 (36%) were more than 14 days after their second dose.
The PM laid out ambitious vaccine targets as he confirmed the goal posts were shifting due to the variant.
He pledged that every adult in the UK would be offered a first dose by July 19, and two-thirds of all adults would be offered a second.
The Tories have faced criticism over not closing the UK's borders to India earlier.
Labour said the country should have been added to the travel 'red list' weeks earlier as the Delta variant first emerged in India, and began spreading there with devastating impact.
Surge testing was introduced and vaccination efforts ramped up in the worst-hit areas as the Delta strain became the UK's most dominant version of the virus.
PHE has previously said data suggests the Delta variant has a 60% increased chance of spreading in homes compared to the Alpha strain, which was first detected in Kent.
