Schools should send home pupils who have a continuous cough or fever as a way help mitigate the impacts of coronavirus, according to new government guidance.
But updated information from the Government says all educational settings should remain open unless directly advised to close by Public Health England (PHE).
On Monday morning Boris Johnson's official spokesperson said closing schools is "not a step we should be taking at this moment in time".
A meeting between the education secretary and school leaders this afternoon, where the issue of school closures was discussed.
Gavin Williamson met representatives from the NAHT school leaders’ union, the Association of School and College Leaders (ASCL) and the Confederation of School Trusts (CST) on Monday, to assess the implications of closing schools and postponing exams.
Schools have been asking for explanations as to why the UK is not following places like Ireland, Italy, New York City and Los Angeles, where closures have all been enforced.
Ahead of meeting Mr Williamson, the chief executive officer of CST said it was "seeking clarity" on what to do about school closures, adding how teachers are working in “extremely challenging circumstances” during a “very fluid situation”.
And over the weekend the largest education union in Europe wrote to the prime minister, asking for "fuller disclosure" around the plan for schools.
Despite concern among leaders about open schools helping to spread the infection, the government has repeatedly said closing them will not be effective.
The prime minister said on Thursday closures now could do "more harm than good", hours after Ireland announced schools and colleges would close for a fortnight.
Published on Monday, new guidance suggests any pupil or staff member with a new, continuous cough or a high temperature should stay home to avoid infecting others.
According to NHS England, a high temperature is generally considered to be 38C or over.
If pupils become unwell at school they should be isolated while they wait for their parents to collect them - ideally in a room behind a closed door, with a window open.
It says if this is not possible, then students should be moved to an area which is at least two metres away from other people, while separate bathrooms should be used.
For any staff dealing with suspected cases of Covid-19, the guidance says they do not need to go home unless they develop symptoms themselves, but adds they should wash their hands thoroughly for 20 seconds afterwards.
Guidance states that, in most cases, school closures will not be needed - but this will be a local decision based on factors such as establishment size and risk of further spread.
If there is urgent public health action to take, the local Public Health England Health Protection Team will contact the school and undertake a risk assessment.
It says PHE will "rarely advise" a school to close, but adds: "This may be necessary if there are so many staff being isolated that the school has operational issues."
Regularly touched objects should be cleaned and disinfected more than usual using standard cleaning products, while young children should be supervised to ensure they wash their hands for 20 seconds using soap and water.
The Government says the guidance, which covers childcare, schools, further and higher educational institutions, may be further updated in line with the changing situation.
In a statement, the Department for Education said: "Today, the Education Secretary met with organisations representing school leaders as part of ongoing engagement to ensure that the coronavirus outbreak has the least possible impact on children’s education, and assure them that any actions taken will be based on the latest medical and scientific guidance.
“The Government’s advice continues to be for all schools to remain open unless Public Health England instruct them otherwise.”
In the letter written to the prime minister, the National Education Union asked why the Government is not closing schools in the same way as other countries, particularly now plans are under way to ban mass gatherings.
The letter said: "We do not have the medical expertise to know what the transmissibility is between children and staff in close quarters in classrooms – but your scientists will have made assumptions about that, together with some view of the certainty of those figures.
"It is very important that we understand what the increased rate of infection is for staff and parents if schools remain open, including obviously for those with underlying health conditions themselves, or for those they care for."
The letter, from the union’s joint general secretaries Mary Bousted and Kevin Courtney, adds: "We know you’ve expressed concerns about children not in school being cared for by vulnerable elderly grandparents, or by NHS staff who would then not be available for work.
"However, we would suggest that parents and schools would be able to work together to find solutions to that - and we would like to know if you have any modelling of such societal responses."
Leora Cruddas, CEO of CST, ahead of the meeting with Education Secretary Williamson, said “It is important to understand that all the big decisions about school closures, exams and the suspension of inspections can only be made by the Government,” she said.
“These are not decisions that regulators can make independently.
“CST’s top priorities, in addition to seeking clarity on these big decisions, will be about the arrangements for safeguarding and welfare of our children and young people, and in particular the most vulnerable.”
Geoff Barton, general secretary of ASCL, said he would be raising the challenges of keeping schools open amid staff shortages, and the potential for disruption during exam season, with the Education Secretary.
He said: “We aim to work through these issues in order to arrive at constructive solutions about the way ahead.
“School and college leaders are showing calm and assured leadership in these difficult times and we can reassure the public that everything that can be done to support young people will be done.”