Pupils continue to mix even when schools are closed during disease outbreaks, research has shown.
A new paper by King's College London has found that "some degree of mixing continued to occur outside of the home" during previous school closures, despite public health recommendations.
Researchers analysed 19 studies, the majority of which reported on school closures during the swine flu pandemic in 2009 and other influenza-like outbreaks, with closures ranging from one day to two weeks.
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Of those, two studies showed a "lack of clarity" over advice of what children could and could not do.
Lead author Samantha Brooks, from the Institute of Psychiatry, Psychology and Neuroscience at King's College London, said: "Of the 19 papers that we identified, all of them reported that some degree of mixing continued to occur outside of the home.
"This is not surprising and, even for adults, self-isolation can be difficult and stressful.
"Ensuring parents understand why school closure is important will be a key factor in determining the success of the measure in the current Covid-19 outbreak.
"In this regard, it was concerning that two studies appeared to highlight a lack of clarity in terms of advice about children's social activities and knowing what children were and were not advised to do.
"Any school closure should be accompanied by clear information on why this measure is being taken and what it should entail.
"Effectiveness of school closure to prevent the spread of Covid-19 will also depend on what other measures are in place."
Published in the journal Eurosurveillance, the analysis showed activities and interaction with others decreased during school closures compared to normal school days.
Older children engaged in more social contact, while younger children remained with their parents for activities outside of the home such as shopping and chores.
Parents generally agreed with school closures but several of the main reasons for disagreeing were related to perceived risk and beliefs that closures do not protect against influenza.
The other main reasons for disagreeing were concerns about the impact on the child's education, difficulties making childcare arrangements and the economic impact.
Professor Andrea Danese, professor of child and adolescent psychiatry at the university, said: "This timely review suggests that school closure can be effective to reduce social interaction and, thus, the spread of infection.
"However, the review also clearly suggests that, for such top-down measures to be effective, children and families cannot simply be seen as passive recipients of government decisions.
"On the one hand, families need to be motivated to engage in collective action through clear information sharing as well as practical and financial support.
"On the other hand, interventions to promote children's mental health can be key to facilitate their compliance in the face of significant demands, such as disruption of education and socialisation."