Schools and universities are the most common setting for COVID-19 outbreaks, according to the latest report from Public Health England (PHE).
As the Department of Health announced that surge testing was being rolled out in targeted areas of Lambeth and Cumbria, latest data shows total outbreaks continued to increase in the week starting 26 May.
This was despite a 39% drop in the number occurring in education.
The PHE report says this coincides with the start of the half-term break and the bank holiday weekend.
Until the end of May, schools and universities consistently accounted for the majority of outbreaks. Almost half of the more than 10,000 incidents in the week starting 19 May occurred in educational settings for under-18s, according to PHE.
Outbreaks in leisure settings are growing in number, as well as a percentage of the total, as people return to public spaces.
The increase is most pronounced in hospitality and travel, which respectively registered 2.5 and 6.2 times as many Delta variant outbreaks in the seven days from 26 May than in the week before. This came a short while after further restrictions on social gathering were lifted on 17 May.
Dr Jenny Harries, chief executive of the UK Health Security Agency, said that the increase in infections is being driven by younger age groups.
Infection rates are currently highest among those aged between 20 and 24 at 243 cases per 100,000 people. This is more than five times the rate for those aged 50 to 54.
Dr Harries said: "Cases are rising rapidly across the country and the Delta variant is now dominant. The increase is primarily in younger age groups, a large proportion of which were unvaccinated but are now being invited to receive the vaccine."
The spread among younger age groups is one of the reasons that the government is rapidly expanding the rollout of its vaccination programme. From today, anyone in England over the age of 18 is eligible to book a jab.
But there will be a lag before this slows infection rates among younger generations. A single vaccine is 18% less effective against the Delta variant than the Alpha one, despite offering similar protection after two jabs.
As of 16 June, less than 17% of under-30s had been double vaccinated, compared with 68% of people aged 30 and over.
The delay in the complete easing of restrictions until next month will allow more time for the vaccination programme to take effect and for scientists to assess the impact of the Delta variant.
Young people have historically experienced lower rates of severe illness and hospitalisation from COVID.
It remains to be seen whether the growth in infections among this demographic will increase pressure on the health system, with data showing a slow increase in hospitalisations among the under-65s in recent weeks.
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