Widespread reopening of schools after lockdowns and vacations is generally not linked to rising Covid-19 rates, a study of 191 countries has found, but lockdown closures will leave a 2020 “pandemic learning debt” of 300 billion missed school days.

The analysis, by the Geneva-based independent educational foundation Insights for Education, said 84 per cent of those 300 billion days would be lost by children in poorer countries, and warned that 711 million pupils were still out of school.

“It’s been assumed that opening schools will drive infections, and that closing schools will reduce transmission, but the reality is much more complex,” said IfE’s founder and chief executive Randa Grob-Zakhary.