Two South Auckland secondary schools have confirmed that one of their students has tested positive for Covid-19.
Catholic girls' secondary school McAuley High School in Ōtāhuhu, and Catholic boys' secondary school De La Salle College in Māngere both have students who have tested positive for Covid-19 and were at school when infectious on 17 August.
All staff and students of both schools are now considered close contacts and must stay in isolation at home for 14 days.
They are being told they must isolate for the full 14 days even if New Zealand moves out of alert level 4.
De La Salle College principal Myles Hogarty said he is concerned as more than 1000 students and staff members at his school might have been exposed to Covid-19.
"This strain seems to be very virulent, it's moving very quickly and we're very concerned of course for our community.
"There's a certain amount of fear and uncertainty amongst them of course, so we're doing all we can to support them."
Anyone who was at school on 17 August will need to get a Covid-19 test on 22 August (day five test) and 29 August (day 12 test), De La Salle College advises in a letter to parents, caregivers and staff.
McAuley High School advises isolation will end on 31 August providing the person has had a negative Covid-19 test result and does not have any symptoms.