WHO says children aged 12 and over should follow the same mask guidelines for adults

Advice on the use of masks for children in the community in the context of COVID-19 – World Health Organization

WHO Q&A: Children and masks related to COVID-19

Commentaries: WHO says children aged 12 and over should wear masks like adults – Reuters AND The WHO just released specific mask guidance for kids as they gear up to return to school: children 12 and older should wear them as adults do – Business Insider