Tougher measures could be taken against schools if control of community coronavirus transmission is lost, according to Scotland's national clinical director.
Jason Leitch urged parents to be "cautious" but not "overly worried" about the return of pupils to class, which is to begin across the country from Tuesday.
However, with fears about an outbreak in Aberdeen growing, he said schools will be in the "equation" if tougher measures are necessary.
The number of cases in the Covid-19 cluster in the city stood at 134 on Sunday, with a total of 728 close contacts identified.
Leitch told BBC Radio Scotland: "It's not the number of positives in Grampian, it’s a matter of community transmission.
"If we, the country, lost control of that outbreak and we couldn't trace a large number of cases back to the original cases from last weekend, that's when we would start thinking about doing things.
"You've seen us already take action last week – about travel, about indoor meeting up, about hospitality – and we won't hesitate to do that in other parts of the country or to take stronger measures in Grampian and Aberdeen if that’s what’s necessary.
"Schools will have to be in that equation, of course they will."
He told the programme that the danger to staff is not "abstract" to him as his wife is in that group and it is a conversation he often has "at the dinner table".
Leitch said his advice is that it is safe for teachers to return, however they should familiarise themselves the relevant guidance.
