Researchers looked at how primary school pupils in Ethiopia had faced since the virus caused disruption to large swathes of normal life - including education.
They found key aspects of their social and emotional development - including their ability to make friends - stalled during school closures and has probably deteriorated.
Other social skills - such as confidence talking to others and ability to get on well with peers - had gotten worse since the pandemic hit, the University of Cambridge research, which looked at 2,000 primary school pupils, found.
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Fewer children agreed with statements such as “other people like me” and “I make friends easily” in 2021 compared to 2019 before the pandemic, they found.
Children who were already disadvantaged educationally - girls, pupils from the poorest backgrounds and those from rural areas - appeared to be the worst hit.
The research, along with another linked study of 6,000 children, also found evidence the Covid pandemic had negative consequences on their academic progress.
The children lost the equivalent of at least one third of an academic year during lockdown, it found, with researchers saying this was a “conservative” estimate.
Professor Pauline Rose from the University of Cambridge’s Faculty of Education said: “Covid is having a long-term impact on children everywhere, but especially in lower-income countries, where it has affected dropout rates, learning, and social skills.
“Education aid and government funding must focus on supporting both the academic and socio-emotional recovery of the most disadvantaged children first.”
Researchers from Ethiopia, Sweden and University College London joined the University of Cambridge with their research.
Professor Tassew Woldehanna, the president of Ethiopia’s Addis Ababa University, said: “These severe ruptures to children’s developmental and learning trajectories underline how much we need to think about the impact on social, and not just academic skills. Catch-up education must address the two together.”
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