UNCERTAINTY over the age at which teenagers are more likely to spread Covid-19 could be grounds for a more cautious approach in secondary schools, a scientist has suggested, as new figures show positive rates amongst teachers have doubled in some Tier 4 areas.

Figures obtained by The Herald show that around 1000 teachers across the regions now under the most stringent restrictions were absent over a recent six-week period because they either tested positive for Covid-19 or had symptoms.

Professor Igor Rudan, Professor of International Health and Molecular Medicine at Edinburgh University, said that issue of whether to keep schools open, particularly in high risk areas, was a “point of intense debate” world-wide.

While he said it is likely that children under 10 are at very low risk of infection and “do not tend to spread the virus” he said the science was far less clear with regard to older pupils.

New York City closed its entire school system on Thursday, prompted by the city reaching a 3 percent test positivity rate, but in-door dining and gyms are still permitted, evidence of different approaches being adopted to combat a second wave of the virus.

The Scottish Government says the research is clear, that closing schools would present a ‘serious risk to the wellbeing’ of pupils, particularly those in more deprived areas.

However, teaching union the EIS argue that no schools in Tier 4 should be fully operational and has warned that staff could carry out “safety strikes” if schools remain open full time. Some parents have suggested at-home learning could apply to senior pupils to help mitigate the risks.

READ MORE: Union calls for schools and nurseries to cut services in Tier 4 areas 

Prof Rudan said areas where people remained in company for longer periods of time such as pubs, restaurants and households remained the greatest source of infections but said we shouldn’t exclude schools from the equation, adding: “This is where we need to wait until science has the answers.”

“We know that children are at very low risk of infection and of adverse effects,” he said.

“There is far more caution about 11-18-year-old children. They may be spreaders.

“I can see that in European countries, many teachers do get infected but do they get infected in the classroom or somewhere else? That is a difficult to answer.

HeraldScotland:

“We would need large-scale community based studies to answer that with hundreds of thousands of participants.”

Public Health Scotland data shows that 0.2% of Scots pupils tested positive for the virus in the first nine weeks of the school term. Of the 1621 cases linked to schoolchildren, the majority - 1,021 - were in secondary schools.

Teacher absences directly related to Covid positive tests have doubled in the past month in some Tier 4 areas.

North Lanarkshire recorded the highest tally from October 6 to November 10, with 222 with sick leave doubling over that time while the number has risen in the past week from 45 to 49.

While the six-week figures also take in the October break, absence rates were highest from October 27 to November 10.  Glasgow recorded 186 teacher absences over that period and numbers have also risen in the past seven days from 47 to 54. The lowest numbers were in Stirling, which did not provide figures due to the risk of identifying staff.

Across all 11 areas in the highest level of lockdown, from October 6 to November 10, 963 teachers have tested positive or been absent due to Covid symptoms. As of November 17, 2645 school staff across Scotland were isolating because  they have confirmed Covid-19 or symptoms or are isolating.

Professor Rudan said our knowledge about children, teenagers and Covid lags behind other age groups because of the additional layers of ethics approval required for such research.

“What we do know is that kids can carry coronavirus and also it can be transmitted within their sub-group but whether this is the main source of transmission or not is a matter of debate and also what is the age limit?

“We know that children are at very low risk of infection and of adverse effects. Why do they seem to be so protected and whether they actually do pass on infections is a matter of debate.

READ MORE: Teachers say school closures should be on the cards as lockdown imposed on 11 council areas 

“I’ve heard a number of hypothesis why children under 10 are not involved in much spreading.

“It seems that they do develop some immune response and it may be because they have so many respiratory infections in any given year.

“Others have said the type of cells they have in their respiratory system are not as developed so the virus has a difficult time getting a hold and entering the body.”

“It’s tricky to do large-scale research on children and transmission patterns. We need the additional layers of ethics approval to do this on kids. So the research is lagging behind research on elderly patients.

“What we also know is that the people who have children in households do not seem to have greater risk of getting Covid than people who do not have children.

“I think the view is that children under 10 are not major spreaders in the community and that 20 to 50 seems to be the age (where transmission rates are highest) which is grounds for keeping the schools open.”

A national Covid tracking app that invites the public to record symptoms every day has now shifted its attentions to schools. The Covid Symptoms Study, which is led by Professor Tim Spector, Professor of Genetic Epidemiology at King’s College London, is asking parents across the UK to request headteachers register their school to help track the virus.

READ MORE: Why are schools open in Scotland? The reasoning behind the decision explained

The Scottish Government say school guidelines are already more stringent with regard to senior pupils including advice to wear masks in the classroom. In response to Prof Rudan’s comments, the government said that it is keeping the guidance ‘under close review.’

Pupils who have been on the shielding list are permitted to have home schooling while the government says the environment can be made safe for teachers.  Should the government by adopting a more cautious approach in terms of closures?

“This is a heartbreaking issue because no matter what you do it is concerning and terrible,”  Prof Rudan said.

“The general thinking is to keep at least the primary schools open for as as long as is reasonably possible. Only when you see a real outbreak should countries consider closing them down.”

As of Friday, at least five Scottish schools and nurseries were currently closed or ‘at risk’ of closure due to Covid-19.

Colmonell Primary School in South Ayrshire, which has 37 pupils, is closed and Highland Council confirmed that Balnain Primary, near Drumnadrochit in the Highlands, which has a school roll of 25, remains shut as well as a partner nursery, Ankerville in Tain.

Two other schools in the Highlands have indicated that they are ‘at risk’ of shutting; Tain Royal Academy and Beauly Primary School.

Torryburn Primary in Fife re-opened on Friday after being closed for nine days due to “a large number” of staff and pupils having to self-isolate for 14 days.

READ MORE: Science shows it is right to keep schools open, say ministers

Dr Ines Hassan, was involved in a report earlier this year by the The Royal Society, the world’s oldest independent scientific academy, which found that the opening up of schools in other European countries had not resulted in notable rises in infection at a national level.

She said: “Keeping children out of the classroom negatively impacts their physical and mental health, results in learning loss, increases educational inequalities, cuts off  essential access to food and heating for many among other issues. “We must put children at the centre of our covid-19 strategy do everything possible to ensure that schools are the very last place to shut.”

A Scottish Government spokesperson said:”At 12 November, the rate of absences due to coronavirus-related sickness among pupils represented about 0.1% of all pupils.

“We are keeping the way guidance is being implemented in schools under close review, along with emerging scientific evidence.

“Where there is a need to take further action, either by updating our guidance or supporting implementation, we will work with teachers, parents, trades unions, local authorities and young people’s representatives to do so.”