Headteachers have questioned why the government is planning to keep close contacts of confirmed Covid-19 cases in school on the basis of potentially unreliable test results.

The Association of School and College Leaders has written to education secretary Gavin Williamson questioning the science behind the plan to use lateral flow tests rather than asking people to self-isolate.

During the past term, anyone identified as being a close contact of a confirmed case was sent home to self-isolate.

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But under the Department for Education’s plan for mass testing, staff and pupils who are close contacts of a Covid case would instead be offered a daily test for seven days and stay in school if the tests remain negative.

Coronavirus: Fears about the reliability of test results

However, the ASCL has questioned this plan amid concerns that the lateral flow tests will not identify all cases of the coronavirus.  

Julie McCulloch, the union’s director of policy, said: “We are concerned that the government has not disclosed the scientific basis for its decision to roll-out mass Covid testing in schools and colleges.

“Under the existing Covid protocols, any close contacts of positive cases are required to self-isolate, but under the approach that the government now wants to implement, these close contacts will undergo lateral flow tests with those testing negative coming into school and those testing positive being sent home.

“However, our understanding is that lateral flow tests generate a proportion of false negative results, and this will therefore mean that close contacts who test negative, but are in fact positive, will be admitted to schools, whereas under the existing system they would be sent home.

“We have written to the education secretary asking him to provide the scientific evidence why this approach is believed to be safer and more effective than the current approach.”

Last month Mary Bousted, joint general secretary of the NEU teaching union, questioned the safety of relying on these tests after an academic estimated that they had only picked up around 3 per cent of positive cases at a university campus. 

Professor Jon Deeks, from the University of Birmingham, has warned that this will result in students with Covid-19 staying in the classroom and infecting others because the tests will return false negatives.

He said that tests carried out on his campus are thought to have only identified around 3 per cent of the positive Covid-19 cases there.

The government has arranged for lateral flow tests to be sent to secondary schools across the country to allow teachers and staff to be tested at the start of term.

There are now fears that the time spent on preparing for mass testing could have been wasted, amid reports that schools are set to be closed across the country.