Greek schools reopened on Monday amid concerns over a new spike in coronavirus infections driven by the Delta variant.
Under government regulations, unvaccinated pupils will have to procure negative self test results twice each week, while teachers will have to take twice weekly rapid tests.
Pupils and teachers are obliged to wear masks.
Only a small number of pupils have so far taken the jab against Covid-19 while an estimated 20 percent of teachers remain unvaccinated.
In-person classes will switch to remote learning if more than half of the pupils get infected.
In comments made Monday, Education Minister Niki Kerameus said the return to full-time, in-class lessons was “main priority.”
She called for strict adherence to safety measures, while urging the vaccination of pupils and teachers against the virus.