Some schools have had to bring back Covid-like measures to prevent the spread of flu, as rates of reported illnesses in schools and other educational settings are higher than this time last year.
One primary school in Leeds said last week it had to cut back on singing in assemblies and introduce sanitisation stations, while another in Caerphilly had to close temporarily.
Flu season has come early this year and some hospitals have asked staff, patients and visitors to wear face masks.
The Association of School and College Leaders said they were aware of winter illnesses causing disruption in "several schools across the UK".
The Department for Education (DfE) in England said school closures "should only happen in extreme circumstances".
