Researchers found school closures alone could reduce UK deaths during the Covid-19 outbreak by as little as 2 per cent.
But the University College London experts warn the costs are “high”, with children’s health and education damaged and family finances hit.
They reviewed 16 studies on the impact of school closures and other social distancing measures in previous epidemics.
They say schools will need to consider how they can protect pupils when they reopen – perhaps staggering start and break times.
Nine in ten students worldwide – more than 1.5billion youngsters – are currently out of school because of coronavirus.
Study leader Prof Russell Viner said: “We know from previous studies that school closures are likely to have the greatest effect if the virus has low transmissibility and attack rates are higher in children. This is the opposite of Covid-19.
“Data on the benefit of school closures in the COVID-19 outbreak is limited but what we know shows that their impact is likely to be only small compared to other infection control measures such as case isolation and is only effective when other social isolating measures are adhered to.
“Additionally, the costs of national school closures are high – children’s education is damaged and their mental health may suffer, family finances are affected, key workers may need to stay home to look after children and vulnerable children may suffer most.”
Prof Viner said policymakers need to be aware of the evidence when considering closures because of the “profound and long lasting effect” they will have on children.
He added: “Countries that have closed schools, such as the UK, have to now ask hard questions about when and how to open schools.
“Interventions in schools, such as closing playgrounds, keeping students in constant class groups/classrooms; increasing spacing between students in classes, reducing the school week and staggering school start and break times across years or classes, should be considered, if restrictive social distancing policies are to be implemented for long periods of time.”
Robert Halfon, chair of the Commons Education Committee, yesterday said he believes there will be staged reopenings of schools when the pandemic begins to ease.
The Tory MP said: “We are walking hand-grenades potentially at the moment in the way that we can spread this disease.
“And that is what lies I think behind the Government’s decision [to impose a lockdown]. I suspect that when things get better, we will be allowed out in stages.
“Vulnerable citizens will probably be told to stay at home and there will be staged openings of schools and restaurants and businesses.
“But the only thing we can do is follow the advice of the Chief Medical Officer and Chief Scientific Advisor.”
The review findings are published in the journal The Lancet Child & Adolescent Health.