Nicola Sturgeon said there are no outbreaks of coronavirus in primary schools after concerns pupils were testing positive.
The First Minister confirmed more cases since the return to class full time in Scotland last week, but said they were linked to communities rather than schools.
"We are not seeing outbreaks in primary schools, we are seeing individual cases of primary school aged children but the evidence so far is they are getting the virus in the community," she said.
"This may not always be the case - we have to contemplate that we may see outbreaks in schools at some stages. But right now that is not what we are facing."
Sturgeon was joined at her regular briefing by Education Secretary John Swinney. He said there is no evidence on school transmission and rejected suggestions face coverings should be made mandatory now to stop infection spreading in the first place.
He said: "At my request, the Covid-19 sub group on children's issues has reviewed the advice on the use of face coverings in the light of experience of schools reopening in Scotland. It noted that although school age pupils in Scotland have tested positive since schools have reopened, there is no evidence that transmission has happened within the school."
Sturgeon said there two new individual cases involving young people in Johnstone and Dundee.
Nine confirmed cases are in a cluster in Lanarkshire, up by one from yesterday.
There have been cases in primary schools in Blairgowrie, Paisley and Perth, as well as in Coatbridge and Glasgow.
Swinney said the move back to class was a major milestone but said guidance is kept under review.
He said: "We are regrettably, but perhaps not surprisingly, now seeing some small clusters involving children and young people across Scotland and reports of new cases have been monitored closely by health teams and local authorities.
"This is of course worrying news, however those affected are self-isolating and local authorities are doing everything necessary to ensure the safety and well-being of pupils and staff.
"The scientific advice has set out that distancing between pupils and face coverings are not required within the school setting, as long as population prevalence remains low and other mitigations are in place.
Swinney confirmed 95% of pupils in Scotland returned to school on Monday.
Yesterday, Sturgeon said she would still consider a part-time “blended” model if the situation got too bad.
