The delay in getting children and adolescents back to schools is a "national disaster" that is putting their mental health at risk, say leading psychologists.
In an open letter to Education Secretary Gavin Williamson, they say the isolation of lockdown is harming already vulnerable young people.
Highlighting the low risk to children of Covid-19, they call for social distancing measures to be minimised.
And for a return to normal life.
In the letter, signed by more than 100 specialists in psychology, mental health and neuroscience, and published in The Sunday Times, they write: "As experts working across disciplines, we are united as we urge you to reconsider your decision and to release children and young people from lockdown.
"Allow them to play together and continue their education by returning to preschool, school, college and university, and enjoy extra-curricular activities including sport and music as normally, and as soon, as possible."
Rising anxiety and loneliness
It comes after an opinion piece in The Lancet Child & Adolescent Health warned of the damaging long-term consequences of a lack of face-to-face contact among young people and their peers.
Prof Ellen Townsend, professor of psychology at the University of Nottingham, who organised the letter, said mental health problems such as anxiety were already rising in young people before lockdown.
She told the BBC there was evidence that growing feelings of loneliness and social isolation as a result of school closures during the pandemic could be making that worse, especially among teenagers.
And she described hearing some "heart-breaking stories" of children struggling.
The letter also points to evidence that children are at low risk from Covid-19.
"Suicide is already the leading cause of death in 5-19 year olds in England and the second leading cause of death in young people globally; thankfully, Covid-19 will never claim this many young lives," it says.
The letter goes on to say that children are being "neglected in this crisis" and "their futures must now be given priority".
Schools were shut across the UK on 20 March in order to reduce the spread of coronavirus. Apart from the children of key workers, most children have not been to school since then and will not enter a classroom until after the summer holidays.
A small number of primary school children have returned in England, but only in small groups.
Signatories to the letter include Prof Sarah-Jayne Blakemore, professor of psychology at the University of Cambridge, Prof Rory O'Connor, chair in health psychology at Glasgow University, broadcaster and author Prof Tanya Byron and Prof Uta Frith, from the Institute of Cognitive Neuroscience at University College London.
From now on, young people must be included in making decisions involving them, they say.
"We need to recognise the sacrifice that children have already made for others and we should not ask for that sacrifice to continue.
"When many of this cohort enter adulthood, we will be deep in recession, so they will need mental resilience and educational preparedness.
"Instead we are damaging both, with lifelong consequences for them and society," the letter ends.