On Thursday, the UN agency closed down its social media channels for the next 18 hours to send one message to the world: #ReopenSchools for in-person learning as soon as possible.
The UN Educational, Scientific and Cultural Organization (UNESCO) joined UNICEF, together with the World Bank, the European External Action Service (EEAS), the European Commission Humanitarian Aid operation, the LEGO Foundation and the WEF Global Shapers community of world youth.
"As classes resume in many countries around the world, millions of students are heading into a third academic year without stepping foot in a classroom," said UNICEF Executive Director Henrietta Fore in a press release on Thursday.
"The losses that students are incurring from not being in school may never be recovered," she added.
New numbers from UNESCO, released on Thursday, show that schools are now fully open in 117 countries, with 539 million students back in class, ranging from pre-primary to secondary levels.
This represents 35 percent of the total student population across the world, compared to 16% who returned to school in September 2020, when schools were only open, or partially-open, in 94 countries.
Around 117 million students, representing 7.5 percent of the total, are still affected by complete school closures in 18 countries.
The number of countries with partly open schools, has declined from 52 to 41 over the same period.
In all countries that had prolonged full school closures, education was provided through a combination of online classes, printed modules, as well as tuition through TV and radio networks.