More than half a million schoolchildren have been forced to isolate in one week, new figures show.
The Department for Education has confirmed that Covid-related pupil absence in schools in England has hit a new record high since all students returned to class in March.
A staggering 561,000 children were estimated to be self-isolating due to a possible contact with a Covid-19 case.
Around 8.5% of state school pupils did not attend class for Covid-19-related reasons on July 1, up from 5.1% on June 24 and 3.3% on June 17.
The figures include 34,000 pupils with a suspected case of coronavirus and 28,000 with a confirmed case of Covid-19.
It comes as Education Secretary Gavin Williamson is set to announce that the school bubbles policy, which forces huge chunks of schoolchildren to quarantine when a classmate tests positive, will be scrapped.
It is expected to be replaced with a strict testing regime.
The Prime Minister's spokesman said the Government would make a statement today, adding: "Obviously throughout this we have needed to balance the public health and the right for children to receive a good education.
"That is what we will continue to do."
Shadow Education Secretary Kate Green, said: "This data shows the Conservatives' staggering failure to keep our kids learning.
"By failing to control our borders ministers have let the Delta variant take hold, forcing kids out of their classrooms and away from their friends.
"Parents, pupils and teachers have had days of mixed messages, what they need now is absolute clarity about what measures will be taken to keep kids in school and stop this spiralling of Covid cases."
Nick Brook, deputy general secretary of school leaders' union NAHT, added: “These latest figures make for grim reading and show that the delta variant is having a huge impact on schools.
"Whilst the government might argue that scrapping bubbles and changing rules around self-isolation will reduce the number of pupils missing education, we should be equally worried about the significant rise we have seen in confirmed and suspected cases in a single week.
"These latest figures only serves to demonstrate why the government must take urgent action and put alternative measures in place to keep school communities safe. Simply hoping the problem will go away is not a realistic option.”
