Teacher shortages could result in pupils being sent home from school if Covid cases continue to rise, ministers have been warned.

Seamus Searson, general secretary of the Scottish Secondary Teachers’ Association (SSTA), said coronavirus mitigations - such as staff and pupils wearing face coverings in secondary schools - should continue in order to avoid such a situation arising.

However, Highland Council education chair John Finlayson said rising cases were already “having an impact on service delivery” and that a return to remote learning was likely where schools were “struggling for staff”.

Related: New Covid rules fuel concerns over safety in schools

News: Covid-positive education secretary keeps working

John Swinney: We want to avoid school closures ‘at all costs’, says deputy first minister

Nicola Sturgeon: Keeping schools open is ‘top of the list’, says first minister

Both Mr Searson and Mr Finlayson made their comments this morning on BBC Radio Scotland’s Good Morning Scotland.

Current plans are for mitigations involving, for example, face coverings in secondary schools to remain in place for six weeks - although the education secretary, Shirley-Anne Somerville, has previously said the rule could be dropped sooner.

Covid: Schools urged to go beyond current anti-virus measures

Meanwhile, changes to self-isolation and testing rules for under-18s, introduced to coincide with the start of the new term earlier this month, have already come under fire.

Tes Scotland revealed earlier this week that the EIS teaching union is challenging the new rules on self-isolation. It says it is now “practically impossible” for a close contact in school to be asked to stay at home until tested - even if they have been sitting beside a positive case in class - unless they have also, for example, stayed over at the young person’s house.

This week both the first minister, Nicola Sturgeon, and the deputy first minister, John Swinney, have been at pains to stress that keeping schools open is their top priority. but Mr Finlayson said: “I think we will see remote learning, even at this time, where there are situations where schools are struggling for staff, where there’s a high number of pupils at home.”

Mr Searson said mitigations may have to remain in place “for a good deal longer”.

He also said ministers need to consider vaccinating 12- to 15-year-olds against the virus, while schools should keep other measures in place, such as staggered starting times.

Asked if there is a risk of Scotland’s schools facing teacher shortages, Mr Searson said: “Most definitely. Teachers are going to contract Covid and they, therefore, will be missing and that is going to be a problem because children will be sent home because the teacher is not there.

“That’s why I think the mitigations are probably going to go on for some time, because if the numbers keep rising I think the government has got no choice but to go beyond the six weeks they first talked about and actually put the mitigations in place for a good deal longer.”

Teachers are “very concerned” about rising Covid levels, he added.

“It was anticipated the numbers would go up but it is so important that all the mitigations that are in place should continue, and people need to remind themselves that the pandemic is not over and schools should try as much as possible to not only follow the guidance from the government but go a little bit further as well.”

He said trying to stop children in different year groups mixing at school “is a no brainer”.

Mr Searson added: “To keep everybody safe, we need to make sure that everybody is vaccinated. Ireland are already vaccinating the 12- to 15-year-olds, and have been doing that for a number of weeks, so I think we need to move on that quickly to keep everybody safe.”

Mr Finlayson said: “I think we will see remote learning, even at this time, where there are situations where schools are struggling for staff, where there’s a high number of pupils at home.”