A teacher wears a protective face shield in a classroom at a flemish primary school during its reopening as a small part of Belgian children head back to their schools with new rules and social distancing during the outbreak of the coronavirus disease (COVID-19) in Brussels, Belgium May 15, 2020. Belgium's primary and secondary schools on Friday (May 15) started preliminary reopenings with smaller classes of final-year pupils under strict social distancing rules as the country continued to ease coronavirus restrictions. REUTERS/Johanna Geron

A woman sanitizes a student's hands at flemish secondary school during its reopening in Brussels, as a small part of Belgian children head back to their schools with new rules and social distancing measures, during the outbreak of the coronavirus disease (COVID-19), in Brussels, Belgium, May 15, 2020. REUTERS/Yves Herman

A teacher takes the children's temperature at the entrance of a flemish primary school during its reopening as a small part of Belgian children head back to their schools with new rules and social distancing during the outbreak of the coronavirus disease (COVID-19) in Brussels, Belgium May 15, 2020. REUTERS/Johanna Geron

A teacher wearing a protective face mask conducts a lesson, at a flemish secondary school during its reopening in Brussels, as a small part of Belgian children head back to their schools with new rules and social distancing measures, during the outbreak of the coronavirus disease (COVID-19), in Brussels, Belgium, May 15, 2020. REUTERS/Yves Herman

Students wearing protective face masks sit in a classroom at a flemish secondary school during its reopening in Brussels, as a small part of Belgian children head back to their schools with new rules and social distancing measures, during the outbreak of the coronavirus disease (COVID-19), in Brussels, Belgium, May 15, 2020. REUTERS/Yves Herman

Students wearing protective face masks sit in a classroom at a flemish secondary school during its reopening in Brussels, as a small part of Belgian children head back to their schools with new rules and social distancing measures, during the outbreak of the coronavirus disease (COVID-19), in Brussels, Belgium, May 15, 2020. REUTERS/Yves Herman