School leaders in England are warning of weeks of disruption owing to high levels of staff Covid absences, which could lead to children being sent home to learn remotely.

One secondary headteacher said he and 26 of his staff had tested positive for the virus, while others were having to stay at home to look after their own children as nurseries were closed, also because of Covid absences.

As the impact of the spread of Omicron over Christmas becomes apparent in Covid data, heads said it was inevitable that some classes and year groups would be sent home to learn remotely because schools would not have sufficient teachers or supply cover.

A number of headteachers and one leading education union have expressed concern about new government advice to combine classes in the event of staff shortages, warning that it risks spreading Covid further and increasing disruption.

In an email sent to schools on Sunday, the Department for Education (DfE) advised heads to deal with staff absence by teaching larger groups, but school leaders said this was not a workable long-term solution, with one warning it could lead to something “like a scene out of Mad Max”.

Geoff Barton, the general secretary of the Association of School and College Leaders, said: “Schools and colleges desperately want to be able to maintain face-to-face teaching on a consistent basis, but the reality is that if large numbers of staff are absent this will cause disruption, which may include having to send home classes or year groups for short periods of time to learn remotely.”

Meanwhile, heads are preparing for “difficult conversations” with some parents after the government called for masks to be worn in classrooms, while others are dealing with time-consuming subject access requests and freedom of information requests over vaccination programmes from anti-vaccination groups.

Boris Johnson said on Monday he was not happy about calling for masks in classrooms but it was a necessary step. “There’s an increasing body of scientific support for the idea that face masks can contain transmission. I don’t like the idea of having face masks in [the] classroom any more than anybody else does, but we won’t keep them on a day more than is necessary,” he said.

With the risk of widespread disruption to schools, Oak National Academy, the national online classroom set up by government when the pandemic first hit, is preparing for increased demand.

“Schools and teachers are doing all they can to make sure pupils have a smooth return to the classroom after the holidays,” said Oak’s principal, Matt Hood. “For those children who cannot be in the classroom, Oak National Academy stands ready to support them.”

Dr Mary Bousted, the joint general secretary of the National Education Union, said it was “alarming” that the education secretary, Nadhim Zahawi, was advocating combining classes of pupils to overcome staff shortages. “Collapsing classes will mix groups of pupils and risks providing the conditions for the virus to spread more rapidly, which will result in greater pupil and staff absence,” she said.

‘A sense of trepidation’

Ben Davis is the headteacher of St Ambrose Barlow RC high school in Greater Manchester, which opens to pupils again on Thursday with a phased return to allow each year group to be tested for Covid. “I do feel a sense of trepidation,” he said.

Masks have been reintroduced into classrooms in his school twice previously on the recommendation of Public Health England because of high infection rates, and Davis had to send a number of year groups home before Christmas owing to staff absence.

As the spring term gets under way Davis fears there will be more of the same and is worried about the impact on summer exams. “My expectation is there will be quite a lot of disruption over the next few weeks and we will have year groups working from home.”

Glyn Potts, the head of Blessed John Henry Newman RC College in Oldham, has himself tested positive for Covid and will not be in school at the start of term. A further 26 staff have also tested positive and he is waiting to find who will be out of isolation and available for work when pupils begin to return to school on Thursday.

“What we are going to get on our return are absences of staff and children and a large number of challenging conversations with parents – those who are for or against masks and vaccinations – all of which distracts and takes time,” he said.