The proportion of pupils who missed classes for virus-related reasons in England more than doubled in early July, as teachers accused government of “doing nothing and hoping for the best”.

The number of primary and secondary pupils absent from school because of coronavirus climbed to about 840,000, its highest level since widespread absence caused chaos in schools in December.

The share of students staying home due to Covid rose to 11.2 per cent on July 8, up from 5.1 per cent on June 24, according to data from the Department for Education published on Tuesday.

The increase comes at a critical moment as the government prepares to lift most remaining lockdown restrictions in England, including those in schools, while the virus continues to spread rapidly.

Nick Brook, deputy general secretary of the National Association of Head Teachers, a union, said the rise pointed to “how the government has lost control of the situation” and warned that failure to take urgent action risked worsening the situation.

“A policy of doing nothing and hoping for the best next term not only fails to address the problem, it risks making things worse,” he added.

Only 1 per cent of children were absent from school as a result of confirmed or suspected coronavirus, meaning hundreds of thousands of uninfected children have missed vital education.

About 8.4 per cent, or 624,000 pupils, were kept home because they may have been in contact with someone in school who had tested positive, while a further 1.6 per cent, or 123,000, had been exposed to the virus outside of school.

Under current policy, students who have had contact with someone who has tested positive for coronavirus are required to self-isolate. In many schools, particularly those with younger children, entire years or classes — known as “bubbles” — have been sent home.

This quarantine requirement and other safety measures, such as classes start at different times to avoid contact between children at breaks and the school gates, and social distancing will be lifted on July 19 along with other lockdown restrictions.

On August 16, the legal requirement to self-isolate after suspected contact will the virus will be lifted for under 18s and fully vaccinated adults.

Under incoming changes, only children who test positive for coronavirus will need to self-isolate when the next academic year begins in September, significantly reducing the disruption to education.

However, teachers have warned that the plan will create a new set of challenges.

Brook dismissed the changes to isolation rules as “not a proper solution” and implored the government to take “urgent action” to prevent future outbreaks.

Geoff Barton, general secretary of the Association of School and College Leaders, said schools would need “substantial support” in setting up on-site testing for students, installing ventilation systems and creating outbreak management plans.

He urged the Joint Committee on Vaccinations and Immunisation to release further information on a pending decision on whether to vaccinate pupils aged 12 and over, so teachers could better plan for the coming year.

Kevin Courtney, joint general secretary of the National Education Union, which represents teachers, said the government’s strategy was based on an assumption that the virus would have passed its peak in September.

“Hoping for the best has been used too many times,” said Courtney. “Our issue is the government isn’t doing enough planning for if things don’t go to plan.”