Dozens of schools across the UK have been hit with coronavirus cases since pupils returned to class.
Some schools have closed their doors just days after reopening while others have told whole classes and year groups to self-isolate for two weeks following confirmed cases of Covid-19.
It came as Health Secretary Matt Hancock suggested young people under 25 – particularly those aged 17-21 – have helped propel the rise in positive coronavirus cases across the country in recent days.
Schools in England and Wales began reopening to all year groups last week for the first time since March and the remainder are due to open this week.
The National Education Union (NEU) is calling for a “more robust and accessible” test and trace system after it said it had heard reports of teachers being told to travel hundreds of miles for a test.
In Suffolk, five members of teaching staff at Samuel Ward Academy in Haverhill tested positive for Covid-19 and the academy closed on Monday on the advice of Public Health England.
Two other members of staff are waiting to hear their coronavirus test results.
The school said the closure was a “precautionary measure” and it hoped to reopen on Tuesday.
In Leicestershire, a member of staff at Castle Rock school in Coalville – which was visited by Boris Johnson on August 26 – has tested positive for Covid-19.
At least 10 schools in Wales are believed to have been affected by coronavirus since reopening.
Cardiff Council announced on Monday that 30 pupils from Ysgol Bro Edern had been asked to self-isolate for 14 days following the confirmation of a case.
The year seven pupils were identified as contacts of a student who tested positive for Covid-19 on Sunday.
A class of 21 pupils at St Gwladys Primary School in Bargoed, Caerphilly, were also told to self-isolate for two weeks after a member of staff tested positive for Covid-19.
Meanwhile, the return to school for some year groups was delayed at Ysgol Bryn Castell in Bridgend and Ysgol Maesteg after members of staff tested positive for Covid-19.
On Monday, the Welsh Government announced more than £2.3 million had been committed to provide free face coverings for all secondary school and further education students.
Liverpool City Council said eight schools have had positive cases of Covid-19 – and it confirmed the year 11 “bubble” at Liverpool College was told to self-isolate after one pupil tested positive.
In Wiltshire, all 160 pupils in year nine at St Augustine’s Catholic College in Trowbridge were told to self-isolate after a student tested positive.
Wiltshire Council said all “precautionary and proper bubble measures” were followed but the school had agreed to take the additional step of asking all pupils in the year group to self-isolate for 14 days.
Coronavirus cases have also been confirmed at three schools in the area around Middlesbrough.
St Benedict’s RC Primary School in Redcar, St Aidan’s CE Primary School in Hartlepool and Outwood Academy Ormesby in Middlesbrough have all seen positive cases – but they will remain open.
The JCB Academy in Rocester, Staffordshire, closed on Friday after a pupil tested positive for coronavirus – and around 100 students were told to self-isolate.
Kevin Courtney, joint general secretary of the NEU, said: “We need a far more robust and accessible trace track and test system with testing centres within a reasonable distance.
“We are hearing stories of teachers being told they must travel hundreds of miles for a test – the Government must act on this immediately.”
Gavin Williamson has claimed the Government is “very much” in control over the return of schools, despite several Covid-19 cases being recorded.
Speaking in the Commons, the Education Secretary launched the defence of the reopening after Labour MP Matt Western highlighted cases in schools.
He told MPs that schools will only ever be closed as an “absolute last resort”.
Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said it is “impossible” to eliminate entirely the risks of transmission either in school or the wider community.
He added: “It is therefore likely that disruption will continue over the coming weeks and months.
“This shows the necessity for a robust contingency plan in case students are unable to take GCSE and A-level exams next summer or their preparation is significantly disrupted.”