Face coverings in secondary school classrooms are to remain in place at the start of the summer term following an "ongoing review of the evidence and data", the Department for Education has announced.
All other safety measures will also continue, including twice-weekly asymptomatic Covid testing of staff and students, smaller group bubbles, increased hygiene, ventilation, and social distancing where possible.
The DfE says: "This cautious approach will help limit the risk of transmission and enable continued monitoring of the effect of school and college returns, as twice-weekly testing is established and embedded in pupils' routines."
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The dropping of the requirement for face masks in secondary classrooms is not expected until 17 May at the earliest.
And it will not be confirmed until after a review of the latest data on Covid infection and vaccination rates.
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The DfE says the delay will allow time for the vaccination programme to reach everyone in priority groups and that all further changes will be confirmed with one week’s notice.
Education secretary Gavin Williamson said: “We introduced face coverings in the classroom for secondary schools and colleges to help reduce transmission in parallel with the introduction of twice-weekly testing.
“Schools and students have done a great job adapting to Covid-secure guidance and working hard to make sure it doesn’t impact learning.
"We obviously all want to get back to face mask-free classrooms and we will do this in line with the latest scientific data while balancing the interests of students, teachers and the wider community.”
The DfE said its face masks policy review took into account "stakeholder intelligence" that it had gathered on the experiences of face covering use in classrooms, and scientific evidence and data from Public Health England.
Those who are currently exempt from wearing face coverings will remain so, including students or staff who are speaking to or providing assistance to someone who relies on lip reading, clear sound or facial expression to communicate.
Professor John Simpson, head of the public health advice, guidance and expertise pillar at Public Health England, said: “The return to school after Easter will allow us to continue monitoring the impacts of measures to reduce the spread of Covid, as we encourage families to test regularly.
“Wearing face coverings in secondary schools is an extra control measure to reduce the risk of transmission to support children continuing their education in the classroom.”
Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), said the advice was "clear" and that his union supported it.
However, he added: "The use of face coverings is clearly not ideal in a classroom setting as it has the capacity to disrupt education and it is not something we want to see going on any longer than is absolutely necessary.
“We hope that the continued excellent progress with vaccinations mean it is no longer necessary for students to wear face coverings in lessons when the government announces the next stage in the easing of restrictions in May.”