Breaking down the risks, it is clear pupils must go back

British parents and teachers need to be sent on what overseas journalists know as a Hostile Environment Training or a “He(e)t” course.

If the Prime Minister were to ask Prof Chris Whitty, the Chief Medical Officer, to broadcast a Covid-specific one, the country would be in a much better place.

He(e)t training is all about assessing relative risk. You can never eliminate it entirely but you can break it down. A handful of bigger risks invariably accounts for 80-90 per cent of the total. By avoiding them you can get on with your job while remaining reasonably safe.

It’s an understanding of risk that allows journalists to operate in war zones and doctors and nurses to function coolly and calmly in virusstrewn wards. It allows the police to fight crime and factory workers to operate lathes. There is an element of courage but virtually anyone can do any of these jobs with minimal risk as long as they are taught to know where the major risks lie.

Unfortunately for the nation, Mr Johnson failed his He(e)t training early on in the crisis. Perhaps he was playing tiddlywinks in the back of the class when the rest of us were being told by Prof Whitty to beware of droplets and to avoid shaking hands.

He was like the war correspondent who didn’t listen to the bit about not standing directly behind a guy with a rocket-propelled grenade. Thankfully he survived the blast, but the nation that witnessed it has been left understandably traumatised.

Nowhere is this more apparent than in the debate over schools. There is a wealth of data from the World Health Organisation (WHO) and others that show the careful opening of schools to be a minor risk in the greater scheme of things.

None of it, as the scientists are careful to say, is “conclusive”, and nor is it likely to be for many years. But here are the key pointers. They are instructive and should not be ignored:

Are children at risk of Covid-19?

Yes, but the risk is minuscule. Children are grossly underrepresented in all Covid-19 case numbers, hospital admissions and deaths worldwide. A study found there were just 43 Covid-related deaths of children under 20 across the US,

England, Italy, Germany, Spain, France and Korea in the three months to May 12, equating to 0.117 per cent of all deaths in the age group. In the same period, 70 times as many (3,000) died in accidents. The authors add: “The direct impact of Covid-19 on children is currently small … the main reason we are keeping children at home is to protect adults”.

How easily do children catch Covid-19?

Nothing like as easily as adults. Alasdair Munro, paediatric registrar and clinical research fellow at University Hospital Southampton NHS Trust, has helped pull together an excellent evidence base on Covid-19 and children. It shows the attack rate within households to be significantly lower for children than adults.

A study in Iceland of “high risk” individuals found half the rate of infection in children under 10 compared to adults.

A study in Italy, which screened more than 85 per cent of the town of Vo, found 2.6 per cent of people had Covid-19 but no children.

And in a Spanish study covering more than 60,000 people, infection rates in children were 1-3 per cent, compared with 5 per cent in adults.

How infectious are children?

This is more difficult to judge. There are examples of children not spreading the virus at all and there are studies that have found limited evidence of children contributing to the spread of Covid-19, although most transmission is adult to adult.

“Children can get Covid-19, so can almost certainly spread it”, concludes Dr Munro. “But, they are barely affected by infection, and appear less likely to catch or spread it than adults.”

What does this mean for schools?

Well, I’m a 55-year-old father of four and I’ve been on He(e)t training. Because of my age I’m at some risk, but I would not hesitate for a moment to send my children back to school. The risks to them are tiny relative to others and – as long as they wash their hands – acceptably low to me too.

I would like to see our schools open for the entire summer while the incidence of the virus is low and (safer) outdoor space can be properly utilised.

In Denmark, schools are making the most of empty fields, stadiums, theatres, museums and galleries. What a contrast to the educationalists we see interviewed on television in Britain, taping off schoolbooks and fussing over desk arrangements.

They are as bad as the Prime Minister, but at the other end of the risk spectrum.