The proportion of schools with one or more pupils off self-isolating because of a coronavirus case has almost doubled in the space of a week, new figures reveal.

The latest Department for Education (DfE) data shows that 29 per cent of state schools had pupils off because of potential contact with a Covid case at their school on Thursday 12 November.

This was up from 16 per cent of state schools the week before.

The figures also show that almost two-thirds of secondaries had pupils off because of potential contact with a confirmed Covid case in their school.

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The DfE has said this was the case in 64 per cent of secondaries last week, up from 38 per cent the week before. 

This has prompted the Association of School and College Leaders to warn the department that schools are now operating on a “chaotic rota system by default”.

The union said that widespread disruption was happening in an “ad hoc manner” because of the “unpredictability of outbreaks”, making it “very difficult” for schools to plan and deliver lessons.

The proportion of primary schools in this position has doubled to 22 per cent in the most recent figures, compared with 11 per cent the week before.

The department’s data also shows that around one in five schools (18 to 20 per cent) had 30 or more pupils self-isolating owing to potential contact with a case of coronavirus inside the school. This has increased from 8 to 9 per cent on 5 November.

Figures published last week, which were the first set since the half-term break, had shown a decline in the proportion of schools with Covid cases.

The proportion of schools with at least one pupil who had to self-isolate fell from 21 per cent on 15 October to 16 per cent on 5 November.

Among secondary schools, 38 per cent reported they had one or more pupils self-isolating because of possible contact with Covid-19 in their school, down from 46 per cent on 15 October and 55 per cent in the last week before half term.

However, today’s data shows the numbers of schools affected by Covid cases is rising again.

The figures also show a drop in attendance on 12 November.  Attendance in state-funded primary schools was 90 per cent, down from 92 per cent and attendance in state-funded secondary schools was 83 per cent, down from 87 per cent.

The accompanying DfE report says: “The drop in attendance is mainly due to the increased number of pupils self-isolating due to potential contact with a case of coronavirus.”

It also said that attendance in state-funded schools had steadily increased from 87 per cent in early September, to a period of stability of between 89 to 90 per cent from 1 October to 15 October. Post-half-term attendance was at 89 per cent on 5 November but decreased to 86 per cent on 12 November.

Kevin Courtney, joint general secretary of the NEU teaching union, said: “The government squandered the opportunity to get the level of coronavirus infection down in schools by including them in a circuit-breaker [lockdown].

“They have failed to make testing available quickly enough, done nothing to reduce class sizes to reduce transmission networks, and not even begun to prepare for the possible introduction of school rotas.

“Schools and families are now having to deal with the reality of rapidly increasing disruption in schools as coronavirus infection spreads through the school population.”  

A Department for Education spokesperson said: “Over 99 per cent of schools have been open every week since term began and millions of pupils are continuing to benefit from being in school.

“The chief medical officer remains of the view that schools should remain open, and has highlighted the damage caused by not being in education to children’s learning, development and mental health.”