The Nam Tu Liem District medical center said it collected samples from students of all grades at the Xuan Phuong primary school. All these students were designated F3, meaning those who have had indirect contact with confirmed coronavirus cases.
One third grader at the school was confirmed to be infected with the coronavirus Sunday, his mother being previously confirmed a coronavirus carrier.
As of Sunday morning, the school has been locked down, with 57 students, 12 teachers and 11 parents quarantined inside.