Schools reopening should be delayed after the Christmas break, a teaching union has urged.
Pupils are due to return in the New Year after the holidays, which begin this week.
But classrooms are already suffering staffing issues because of the rule for full households to self-isolate for 10 days if someone tests positive for covid, the Scottish Secondary Teachers Association (SSTA) said.
Last January saw schools shut and pupils left to complete work remotely as the UK entered a second national lockdown.
But Nicola Sturgeon has previously insisted that schools would only be shut again as a last resort, the Daily Record reports.
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It comes as the Scottish Government considers imposing even more restrictions on the public as part of its response to the sudden rise of the omicron variant.
The First Minister will make another covid statement on Tuesday afternoon after already warning the public to stay at home if possible.
Seamus Searson, general secretary of the SSTA teaching union, claimed he was already being told of schools that were not fully staffed due to the rising number of covid cases.
And he said parents were keeping their children off to ensure they did not catch the virus in the run-up to Christmas.
"At the moment, schools are struggling to keep open because of the number of teachers who are away because of the virus," he told BBC Radio Scotland.
"We need to be reasonable and say that the virus will spread inside schools.
"There somehow seems to be a notion that the virus isn't spread in school and teachers are immune."
Almost 6,000 new cases of coronavirus were reported across Scotland on Sunday, with Omicron now the dominant variant.
