A man who tested positive for Covid-19 spent half an hour in North Shore Hospital may have come into contact with up to 20 staff last Thursday, the Waitemata District Health Board says.
The man bypassed the hospital's front-of-house screening processes while staff were assisting another person and hid from security staff before running into a lift.
Director-general of health Dr Ashley Bloomfield says people who try to deliberately avoid security arrangements in hospital are putting staff and patients at risk.
Prime Minister Jacinda Ardern said the person would understand the magnitude of what happened.