Parents are being warned to "control their teenagers" as many prepare to head back to school in September.
Students across England could head back into classes later this year after schools were closed in March due to the coronavirus outbreak.
And as the government continue to take steps to easing restrictions, social distancing must remain in place for the forseeable future.
This is why parents are being told to remind their teenagers that they still shouldn't touch when they meet together again.
And Dr Jenny Harries said the real danger could be what happens before and after school – when people from different households are still supposed to stay apart.
England's Deputy Chief Medical Officer told a Downing Street press conference: "The transmission risks were potentially more in the social behaviours of the teenagers – the older children out of school – than they potentially were in school.
"School is quite a controlled environment.
"And perhaps [we are] trying to encourage families [to] control their teenagers in their social interactions outside of school as well."
She added: "In many ways we should be more concerned with what the teenagers are doing outside school.
"So if they're in school in a controlled environment, with hierarchies of control and people keeping an eye on them, that's probably a much lower risk than if they were out of school doing their own thing."
According to Mirror Online, more than 100 suspected or confirmed outbreaks were reported in England’s schools in June.
Forty “acute respiratory infection incidents” in schools or nurseries were reported to Public Health England in the week to June 30.
The figure refers to confirmed or suspected outbreaks, not all of which turn out to be Covid-19
That compared to 44 confirmed or suspected outbreaks the previous week; 24 the week before and 15 the week before. An outbreak is defined as two or more linked cases.
Education Secretary Gavin Williamson suggested local school shutdown, like in Leicester, would "avoid the situation where we will ever have to see a national shutdown again".
But Dr Harries warned Britain could yet face "waves and waves" of coronavirus breaking out nationally.
She said : "A second wave is quite a possibility – that is not ruled out at all. A second peak, as in an epidemic peak, is also not ruled out.
"In fact, in pandemics you can sometimes see successive ones – so we're talking about a second, but you can get waves and waves."
It comes after the government unveiled hardline guidance for the reopening of England's schools to all children, full-time from September.
Unions had pleaded for extra money to open up classrooms in public buildings and have "blended" learning from home.
But instead the government is telling schools to use exactly the same space they had before the pandemic.
No money will be given for extra classrooms and schools are banned from running "rotas". Pupils are expected in five days a week and there will be fines for absence.
To squeeze everyone in, Education Secretary Gavin Williamson will scrap the 15-pupil size limit on class "bubbles" – who stay together to stop the virus spreading further.
Bubbles will now be an entire 30-pupil class or even an entire year group.
Despite the massive increase, the rule that children must automatically isolate if one member of their bubble tests positive has been scrapped.
Instead, a whole class or year group may have to stay home if an outbreak is detected in a school – but this will be decided on a case-by-case basis.
While staff are told to keep two metres apart from pupils where possible, the guidance accepts that in many cases that won't be possible between the pupils themselves.
Asked if the new rules were safe, Mr Williamson claimed: "We’ve seen the creation of safe environments and thats the type of environment we’re going to be creating."
But Dr Harries warned: "We can’t guarantee absolute safety for anybody anywhere in the UK. We have to be realistic.”
She added she would have been "concerned" if the plan was put forward earlier in the pandemic, but infection rates have now decreased.