The Educational Institute for Scotland’s (EIS) general secretary Larry Flanagan said it was premature to scrap isolation for daily testing, and warned that science should not give way to “political expediency”.
The EIS was responding to remarks by national clinical director Jason Leitch on Sunday the stay-at-home for ten days rule for pupils who had been in contact with someone with Covid may be replaced by daily testing for the same amount of time.
Prof Leitch said a third year of disruption to schooling was “unthinkable” and the success of the vaccination programme was paving the way for the potential scrapping of the quarantine period.
Ministers in England are also expected to announce that pupils there will no longer have to isolate after contact with a positive contact case.
Prof Leitch said: “Let's not forget that this is still a horrible disease; you can still be very sick from this virus. But the science is beginning to look like we might be able to replace strict contact self-isolation, maybe with routine testing. You might do that daily.
"Over the summer, before the schools go back, there will be some decision made about what isolation might look like."
However, the EIS said an increasing number of parents had taken their children out of school before the summer break because of fears over rising infection levels in classrooms.
Just under 30,000 pupils were not attending schools because of closures, being told to self-isolate or being kept at home as a precaution by parents – nearly a 40 per cent rise since June 15.
Mr Flanagan said: “It has been agreed that schools should reopen with the same mitigation in place as when they closed for summer.
"Clearly, the Scottish Government is hoping to relax some rules over the summer, but it is important that schools reopen in a cautious manner, especially given the record levels of pupil infection being seen in the final week of term.
"Some mitigation will need to remain in full force, for example, effective ventilation of classrooms, good hygiene regimes and potentially masks in communal areas, especially if this is the norm outside of schools.”
He added: "Completion of vaccination programmes for all school staff is vital and there is a major decision required around the potential vaccination of 12–18-year-olds. Everyone is keen for as much normality as possible, but it is premature to think that the pandemic is on the wane.
“The EIS would be wary about moving away from contact tracing in schools, if this remains the main mitigation outside of school. It’s important that the science isn’t compromised by political expediency.”
However one parents group, UsForThem Scotland said the Scottish Government should change the rules so that only children with positive tests should be asked to leave school for the required period.
Jo Bisset, UFTScotland organiser said: “No-one’s disputing that an unwell child with a positive Covid-19 test should go home to get better.
“But in recent weeks and months, whole classes have been sent home because of a single result. That’s incredibly disruptive.
“When the schools come back, it’s essential pupils have a clear run at the year without unnecessary disruption.”