It is not a question of whether it is “safe” to open schools but of whether it is “safe enough”, a leading public health academic has said.

Devi Sridhar, professor of global public health at the University of Edinburgh, said the Government needed to decide what “threshold of risk” is acceptable to the public.

Speaking on Sky’s Sophy Ridge On Sunday, she said in order to earn their trusts, politicians must be “completely honest with teachers and parents about scientific uncertainty”.

“We know children carry the virus, we don’t know the degree they transmit it to adults,” she said.

We need to have monitoring in place – testing, tracing and the ability to break chains of transmission and identify quickly clusters in schools

Prof Sridhar said: “We need to have monitoring in place – testing, tracing and the ability to break chains of transmission and identify quickly clusters in schools.”

She said it was also not clear what the link is between Covid-19 and the rise in the number of cases of a condition resembling Kawasaki disease during the pandemic.

The mysterious inflammatory syndrome mainly affects children under five and some doctors think it could be triggered by Covid-19.

Prof Sridhar said decision-making on reopening schools would not necessarily be uniform across the country: “In some parts of the country when we look at local authorities, there are thousands of daily cases – look at the north-east of England.

“In other parts there are a few dozen – it obviously makes a difference whether you are going to open a school when there is a lot of community transmission or where there is very little.”

Former Ofsted chief inspector Sir Michael Wilshaw said it was up to Government to decide what measures should be in place to protect schools, and give the task of policing them to local authorities.

Speaking to Sky News, he said: “It is no good saying we are going to let schools do what they want because some schools will do it extremely well and other schools won’t.

“Some schools will ensure there is a triage system in place, there is temperature testing and classrooms are intensively cleaned and so on.

“Other schools might not be doing that, so it is really important that the Government is very prescriptive in what they would expect schools to do.”