Schools are facing a staffing crisis as absences and a shrunken supply pool increase the risk of pupils being sent home.

It comes amid growing fears over a significant rise in Covid infections driven by the Omicron variant and social mixing during the festive period. Pupils are due to begin returning to class from today following the Christmas break.

One senior staff member told The Herald there were intense worries about how her school would cope and said there was “no” supply cover to help.

Although uncertainty remains over how absence rates will change in the coming weeks, union leaders said the possibility of gaping shortages highlighted the need for schools to prepare for remote learning.

READ MORE: Schools may need remote learning to 'protect education'

They warned that losing high numbers of staff would deliver a major hit to the quality of in-school teaching and said online methods could provide a more coherent educational experience during periods of disruption.

Ministers have recently sought to boost classroom safety. Updated Covid guidance was released last month and 12- to 15-year-olds are being offered the opportunity to bring forward their second vaccination.

The government has also underlined the importance of secondary pupils without symptoms taking at-home lateral flow tests the night before going back to school or on the morning of their return. After that, testing should be done twice weekly.

Education Secretary Shirley-Anne Somerville said previously that her "absolute priority" was keeping schools open safely and minimising disruption to learning. 

But deep concern persists over the impact of teacher absences during the busy January-March period. 

HeraldScotland: Seamus Searson warned the supply teacher pool had "dwindled away".Seamus Searson warned the supply teacher pool had "dwindled away".

Seamus Searson, general secretary at the Scottish Secondary Teachers’ Association, warned schools were facing multiple pressures. “The number of supply teachers has dwindled away,” he said.

“There was a lot of bad feeling among supply teachers during lockdown last year because they weren’t getting work, so some of them decided they weren’t going to be treated like that and got other jobs.

“Equally, you have people of a certain age who might not want to go for supply because they’re over 60, or they’re caring for someone who’s vulnerable.”

Mr Searson stressed his union had asked ministers to delay the return to school so the latest Covid wave and its ramifications could be better understood.

He also said intense discussion would be needed around issues such as risk assessment, additional mitigations and preparation for remote or blended learning if absence levels are as high as feared.

READ MORE: 'Almost inevitable' Omicron cases will rise as schools go back

He added: “I feel we’re going to end up with some form of remote learning in the very near future but none of this has been planned for.

"We were told the schools are going back as normal in January with extra mitigations, which are welcome but they’re not enough. There was no plan B for this term.

“The number of staff who are off is a serious concern. The second [area of concern] is lack of supply. And then there is the increased rate of infection.”

Larry Flanagan, general secretary at the EIS union, said: "Clearly many teachers will be nervous about schools reopening as Omicron has continued to spread rapidly over the festive period.

"Although mitigations have been updated, there is essentially nothing new in the safeguards so revisiting risk assessments to take cognisance of the increased transmissibility of Omicron is essential, especially for staff with heightened vulnerabilities. Staff absences may well be high, and given that supply staff are few and far between, schools may need to consider short periods of remote learning to maintain coherent continuity of learning.

"Keeping schools open is the preferred option but there can  be no compromise in terms of staff and student health and safety no matter what the political imperative may be.”