Prof Spector’s guidance contradicts that from the Department for Health, which continues to state that if a child has a new continuous cough, a high temperature or a change or loss to their sense of taste or smell they should be tested for coronavirus.

A letter circulated to all schools at the beginning of term outlined the same set of symptoms as the basis for getting a test.

The symptom tracker, which is used by four million people, has revealed that the majority of children who test positive for Covid-19 suffer from fatigue and a headache. Around half have a fever, while more than a third have a sore throat and a loss of appetite. 

One in six children have an unusual skin rash while a third have none of the 20 potential symptoms listed on the app, suggesting they are asymptomatic.

By comparison, almost 90 per cent of adults have the virus report fatigue, while nearly three quarters have a headache and around half, a persistent cough and a sore throat.

Prof Spector wrote on Twitter that the Government appeared reluctant to widen the “meagre” list of symptoms in case it increased demand for testing, even though it was “inappropriate for children.”

He said more clarity was needed to deter people from trying to get a test, stressing that even the three main symptoms for adults – a continuous cough, a fever and loss of smell – had to be dramatic to be Covid.

“It’s a persistent headache that lasts a few days, the fatigue is not just that you need to sit down, but that you can’t get out of bed,” he told the Telegraph.

He said he thought the Government was too worried about confusing the public to change the messaging but that we had ended up with “a lot of panic and hardly any cases in some areas” – such as the south west and the south east.