The government has been told by its own scientific advisers to prepare for a “high prevalence” of coronavirus in schools by the end of September. 

In its latest consensus statement on Covid-19, published today, the SAGE group warns that it is “highly likely that exponential increases will be seen in school-attending age groups after schools open”.

It also warns that vaccination will have made “almost no difference in these population groups over the summer holidays”.

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And it highlights that measures to curb the spread of the virus in schools will be reduced in the autumn term, compared with last two terms of the 2020-21 academic year.

The statement says: “When schools reopen, the mitigations in place to limit transmission within schools will be much reduced compared to the spring and summer terms.

“Additionally, the prevalence of infection in the community and school-age groups will be higher than in May 2021.”

It adds: “It is highly likely that high prevalence will be seen within schools by the end of September 2021.

“This may reflect either community or within-school transmission, and the role of schools in driving wider transmission remains uncertain.

“Regardless of this, it would be sensible for government to plan for this eventuality.”

A Department for Education (DfE) spokesperson said: “Education remains a national priority, and the plans for autumn will make sure schools and colleges deliver high-quality, face-to-face education to all pupils with minimal disruption. We know that being out of education causes significant harm to educational attainment, life chances, mental and physical health.

“Thanks to the success of the vaccine programme, we are able to return closer to a normal education experience for the autumn term.

“The measures in place strike the right balance between making schools safe with enhanced ventilation, Covid testing and vaccinations of older students and staff, and reducing disruption by removing bubbles and face coverings.”

Launching the government’s “Back to school and college” campaign this week, education secretary Gavin Williamson said the start of the autumn term would mark “the point when our focus can shift away from the disruption of Covid and on to learning, enrichment and recovery”.

But the NEU teaching union has said secondary school leaders will want to consider using face masks and keeping social distancing where possible when students return to the classroom.

And the NAHT school leaders’ union has warned it would be “naïve to assume that things will be completely back to normal in September”.

The DfE also announced on Saturday that it will spend £25 million providing 300,000 portable cabon-dioxide monitors to state schools from September, which will enable teachers to identify where ventilation needs improvement and “act quickly”.

However a survey conducted for Tes has suggested four in five teachers do not feel reassured by the move.