The NEU teaching union has called for schools to be closed during a four-week national lockdown to all but vulnerable children and those of key workers.
The union has also said that schools should be moved to a rota at the end of the lockdown period.
It made this call ahead of a press conference this afternoon in which prime minister Boris Johnson is expected to announce new national lockdown measures in an attempt to bring down the transmission of Covid-19.
However, schools are expected to remain open in a new national lockdown.
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Mr Johnson has so far resisted pressure to introduce nationwide restrictions, opting instead for a localised tier system, but he is reportedly considering closing everything except essential shops and education settings for a month from Thursday.
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Kevin Courtney, joint general secretary of the NEU, said: “It is clear from Office of National Statistics data that schools are an engine for virus transmission. It would be self-defeating for the government to impose a national lockdown while ignoring the role of schools as a major contributor to the spread of the virus.
"Such a lockdown would impose pain on the whole community – but not be as effective as it could be if schools were included. Ignoring the role of schools and colleges in the spread of the virus is likely to lead to the need for even longer lockdowns in future."
Mr Courtney added that the latest figures from the Office for National Statistics suggest that 1 per cent of primary pupils and 2 per cent of secondary students have the virus and that these levels have increased dramatically since wider opening of schools in September.
He said that NEU analysis of ONS figures shows that virus levels are now nine times higher amongst primary pupils and 50 times higher amongst secondary students since the start of term.
The union has previously called for rotas to be introduced into secondary schools in high-risk areas for Covid-19 and for schools to close as part of a two-week "circuit-breaker" lockdown.
Mr Courtney said: "The National Education Union called for a two-week 'circuit break' over half-term to include schools, which the Wales government and the Northern Ireland assembly have done – but the government in Westminster has ignored this call. More severe measures are now called for as a result. The government should not make this mistake again.
"The government should include all schools in proposals for an immediate national lockdown and, as a minimum, be preparing for school rotas at the end of that period, including by actually meeting its promise to deliver broadband and equipment to those children who do not have them.
"It is also vital that the government ensure proper financial support for all those affected by lockdown, including crucial supply teachers and other staff.”
The prime minister is expected to be joined by Professor Chris Whitty and Sir Patrick Vallance in Downing Street at 6.30pm, following a meeting of his Cabinet earlier in the afternoon.
The policy shift comes after new data showed the extent of cases across England. The ONS estimated that 568,100 people in households were infected with the coronavirus in the week ending 23 October.