The head of managed isolation and quarantine says it's unclear where and how a group of fishermen who recently arrived in New Zealand contracted COVID-19.
Eleven of the 237 fishing crew members tested positive for coronavirus on Tuesday after arriving on a flight to Christchurch from Russia last week, with an additional 14 cases under investigation. They are in managed isolation at Christchurch Airport's Sudima Hotel.
The positive tests were detected during day three of mandatory managed isolation testing, and the Ministry of Health is investigating.
Officials and experts are confident the outbreak poses minimal risk to the community. The fishermen are the only group staying at the hotel.
Head of managed isolation and quarantine Air Commodore Darryn Webb says people can be confident the cases are contained to the facility.
"That's exactly why we have 14 days' managed isolation when they get to New Zealand, and we take that approach extremely seriously - we've worked hard to be in a place where we are," he told The AM Show. "We'll just continue to do the right things here; we'll keep them in isolation, we'll be doing daily health checks and making sure they're getting the care that they need."
Webb said it was "hard to say" where the fishermen contracted the coronavirus.
"The indications that have been brought to me this morning [Wednesday] is they are asymptomatic - however, we're working closely with [the Ministry of] Health all the way through.
"We've got extremely robust systems and we've been refining and honing those things right from the start - we take every precaution we can as additional safety layers."
Additional tests will be offered to staff working in the facility should they want them, he said.
"We have a routine testing regime for all of our people - if we have a positive case, as in the case of the Sudima - every seven days those staff will be tested. We've been speaking to [the Ministry of] Health and we're looking to enhance the opportunity for staff to get more testing if they feel that's something they'd want to do, as well as also potentially offering that up for their family."
The fishermen reportedly had pre-departure testing - something that's not mandatory - in Russia and Ukraine before leaving for New Zealand, all of which returned negative.
Director-General of Health Dr Ashley Bloomfield is expected to provide further details on Wednesday.