Teachers are more likely to get Covid-19 on their coffee break than in a classroom, England’s deputy chief medical officer has said.

Jenny Harries said that the risk for teachers in schools was probably highest “between staff”.

Dr Harries also said it would be “unlikely” that there would be a scenario where all schools across the country would be forced to close again.

But in areas subject to a local lockdown there could be individual schools forced to close.

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She said that no environment was “risk free” but added that the risk to children was higher from seasonal flu compared to the current risks posed by Covid-19.

And she said that a single case in a school “bubble” may not lead to the whole bubble being forced into isolation.

Her comments came after the UK’s chief medical officers issued a joint statement seeking to reassure parents that it was safe to send their children back to school.

Dr Harries told Sky News: “We think it’s vitally important that school stay open but obviously when it’s safe to do so.

“There will be rare occurrences where we may recommend that a school closes, and that will be related (to) community transmission rates, rather than necessarily from the school itself.

“We think that transmission risks within the school are low, as long as the measures that have been recommended are put in place.

“But where you get rising transmission rates… then obviously we may make an individual recommendation for a school but increasingly that will be very localised. It’s very unlikely that we would see all schools closing down at one go.”

She added: “So we’re not saying it, no environment is completely risk-free. Every time the parents send their child off to school pre-Covid they may have been involved in a road traffic accident, there are all sorts of things. And in fact that risk or the risk from seasonal flu, we think is probably higher than the current risks of Covid.”

On coronavirus transmission rates, she said that community transmission risk “is far more important than schools”.

Dr Harries added: “The transmission from younger children - when teachers are perhaps more likely to be closer to them - is much lower.

“Actually in the studies that have been done so far, the risk probably of transmission between staff, rather than to or from children, is the one that teachers perhaps should be focusing on - so it’s going off for a coffee break, you know, dropping your guard down.”

Speaking on BBC Breakfast, she added that the majority of cases in schools were from staff-to-staff interactions.

She added: “I think it’s really important to reassure teachers on that count, but also to encourage them. When it’s their coffee break and they get a well-earned rest in the day, to ensure that they maintain their social distancing, good hand-hygiene, all those sorts of things while they have their break because that does seem to be a risk factor.”

When asked if one case was detected in a school “bubble” she replied: “These systems are set up very much that as soon as an individual cases detected - as long as that’s reported through Test and Trace and through Public Health England - contact tracing will go on.

“It may not always be necessary for a bubble to go into isolation, and you need to listen very carefully to the local public health advice, and the contact-tracing teams.

“So get tested, anybody who has symptoms, whether it be teachers, or children, get tested as quickly as possible and take yourself out of circulation, and then test and trace, and the local health protection teams will give you advice on that.”

Asked about whether children over 12 should be wearing masks in schools she said the evidence is “not strong” and among children under the age of 15 “compliance isn’t strong”.

Dr Harries was speaking after teachers were told by Public Health England to “be vigilant” about Covid-19 safety as a report shows the majority of outbreaks in reopened English schools were among staff rather than pupils.