Covid-19 infections continue to rise among children between the age of 5 and 17 despite falling in all other age groups, according to the latest findings.
This could be linked to schools staying open during the lockdown, according to researchers.
Around one in 50 of those aged between 13 and 17 test positive – double the rate of the general population, the latest round of the Imperial College's Real-time Assessment of Community Transmission study has found.
The report, which includes data from home coronavirus tests taken between 13 and 24 November, shows that an estimated 0.96 per cent of England’s population has the virus, or around 1 in 100 people.
This is a 30 per cent drop compared with 2 November.
Responding to the release of the results from Round 7 of Imperial College’s REACT-1 coronavirus survey, the NEU teaching union called on education secretary Gavin Williamson to let vulnerable teachers work from home.
Kevin Courtney, joint general secretary of the NEU, said: "Given that the rate of coronavirus infection among school pupils is now higher than at the start of the lockdown, it cannot be right for the government to tell clinically extremely vulnerable staff that they have to return to the classroom on Thursday.
"This is a small number of staff – just 2 per cent of the workforce – and we call on the secretary of state to show some humanity and to let them work from home in safety.
"Whatever the attitude of the secretary of state, the National Education Union will support its CEV members in continuing to work from home."
Mr Courtney added: "We are deeply concerned by the results of the REACT-1 coronavirus survey, which show that over the lockdown coronavirus has continued to increase among school-age children, whereas it has fallen for every other age group.
"This high and increasing rate of infection among school-age children means that school attendance will remain unacceptably low.
"The government really should have accepted the NEU advice that schools should have formed part of a circuit break."
A Government spokesperson said: “We are prioritising children’s and young people’s education and wellbeing, by keeping nurseries, schools, colleges and universities open.
“The Chief Medical Officer remains of the view that schools should remain open, and has highlighted the damage caused by not being in education to children’s learning, development and mental health.
“Advice for clinically extremely vulnerable people has been updated, tailored to their tier from 2 December. This advice is no different for education settings, as it is for any other workplaces.”