Children who develop a continuous cough or fever at school should be sent home with suspected coronavirus, fresh guidance issued by the government says.
However all educational settings should remain open unless directly told to close by Public Health England, according to the updated advice.
The guidance covers childcare, schools, further and higher educational institutions and could be updated in future as the COVID-19 pandemic develops.
The potential for widespread school closures in the UK has been raised as the outbreak of the coronavirus continues, especially given other nations have ordered children to stay at home.
But the PM’s official spokesperson said the scientific advice is this is “not a step we should be taking at this moment in time” but equally is “not something that we have ever ruled out”.
Education Secretary Gavin Williamson will meet with school leaders later on Monday.
The government guidance says any pupil or staff member who has a new, continuous cough or high temperature should remain at home to avoid infecting others.
A high temperature is generally considered to be 38C or over.
If pupils fall ill at school the guidance states that they should be isolated until their parents come to get them, ideally in a room behind a closed door and with an open window.
If this is not possible, students should be placed in an area which is at least two metres away from other people, while separate bathrooms should be used.
Staff who deal with suspected coronavirus cases do not need to go home, unless they develop symptoms themselves, according to the guidance.
But the advice says they should wash their hands thoroughly for 20 seconds afterwards.
Schools should ensure that regularly touched objects are cleaned and disinfected more than usual using standard cleaning products.
In addition, young children should be supervised to ensure they wash their hands for 20 seconds using soap and water.
According to the government, school closures will not be necessary in most cases.
But its guidance states that this will be a local decision, taking into consideration factors like the size of the educational establishment and the risk of further spread of COVID-19.
If urgent public health action is required, the school will be contacted by the local Public Health England Health Protection Team and a risk assessment will be carried out.
The guidance says that 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.”