Countries like the UK that have closed schools to help stop the spread of coronavirus should ask hard questions about whether this is now the right policy, says one team of scientists.
The University College London team says keeping pupils off has little impact, even with other lockdown measures.
But a scientist whose work has informed the UK strategy insists school closures play an important role.
The government has said it will review its coronavirus policies after Easter.
While children can catch coronavirus, they rarely get severe symptoms.
But they can still spread the infection, which is why many countries have closed schools.
What does the research show?
The research, published in The Lancet Child and Adolescent Health, looked at 16 studies – some based on the spread of coronavirus, and others on seasonal flu and the 2003 Sars outbreak. The findings suggest:
While school closures help during influenza outbreaks, the same may not apply to coronavirus
Data from the Sars outbreak (in mainland China, Hong Kong, and Singapore) suggest that school closures did not contribute to the control of the epidemic
Recent modelling studies of Covid-19 predict that school closures alone would prevent only 2%-4% of deaths, many fewer than other social distancing interventions
How reliable are the findings?
One of the research authors, Prof Russell Viner, said: “Data on the benefit of school closures in the coronavirus outbreak is limited, but what we know shows that their impact is likely to be only small.
“Additionally, the costs of national school closures are high – children’s education is damaged and their mental health may suffer, family finances are affected.
“Policymakers need to be aware of the equivocal evidence.”
He says policymakers must weigh up the possible harms and reopen schools at the earliest opportunity – and not necessarily wait until September if it can be done safely sooner.
Prof Neil Ferguson, from Imperial College London, worked on the scientific modelling that the current government advice is based on. He says the Lancet research fails to take into account the impact that school closure can have alongside other lockdown measures.
“When combined with intense social distancing it plays an important role in severing remaining contacts between households and thus ensuring transmission declines,” he said.