There is one new Covid-19 case in managed isolation.
There are no new Covid cases in the community.
The case reported today arrived from Singapore on October 31 and has been transferred to the Auckland quarantine facility.
Twenty-four previously reported cases are now considered to have recovered, bringing New Zealand's total number of active cases to 44.
Since identifying the positive test results in the two women who work in the managed isolation facility at the Sudima at Christchurch Airport, the Ministry of Health says systems have rapidly worked to put a ring around the virus and stop it from spreading in the community.
The first health care worker, a woman in her 50s, reported as testing positive sought a test quickly after developing very mild symptoms, even though they had just been tested two days earlier.
The ministry says this swift action allowed officials to rapidly isolate the first case and trace and test contacts.
Officials then identified a further positive case in another health care worker, a woman in her 20s, and quickly traced and tested contacts.
Widespread testing had taken place in the managed isolation facility and in the contacts of the two infected workers.
Staff who worked at the Sudima Hotel since October 23 have been tested, with all 193 returning negative results.
All of the infected health care workers contacts had returned negative results, except for one, where the result was still outstanding.
"Investigations are ongoing to determine when exactly the health care workers were exposed to the virus, but we believe them to have been infected by the international mariners they have been caring for, 31 of whom have tested positive for Covid-19," said the ministry.
The genome of the first infected worker was B1.1.7. Of the international seaman at the managed isolation facility who had tested positive for Covid-19, five were part of the B1.1.7 lineage.
With an exact match this indicated a high likelihood that one of these guests was the source of the health care worker's infection, said the ministry.
Health officials were still awaiting genome sequencing results for the second infected woman.
Both health care workers wore PPE while conducting their work, said the ministry.
A review would be undertaken at the managed isolation facility to assess where procedures could be improved to prevent similar infections in the future.
Meanwhile, the hundreds of fishermen who arrived from Russia and Ukraine last month have had their stay in managed isolation extended.
The Community and Public Health team was still working on an exit plan for the mariners, who would be transferred directly onto their ships once released from managed isolation.
Yesterday there were two new cases of Covid-19 in managed isolation with 67 active cases in New Zealand. There were no new community cases.
The most recent infections included a traveller who arrived from Singapore and a person who joined a family member in managed isolation who had previously tested positive for Covid.
But it is the latest Christchurch outbreak that has the southern community on edge.
Hundreds of people turned out to testing stations this week after it was revealed two female healthcare staff working at the Sudima Christchurch Airport where hundreds of Russian and Ukrainian seaman were in managed isolation had contracted Covid.
A decision is still to be made when the fishing crew would be allowed to leave the facility. Midweek it was announced the men would likely finish their lengthened stay in quarantine on Friday.
Yesterday health officials said this depended on investigations into the community spread that linked one case directly with crew members.
Genomic testing of a woman in her 50s who tested positive for covid was the same strain as five of the sick crewmen.
The results of genomic testing of a second sick worker, a woman in her 20s, were still being sought.
With a fresh community outbreak scare in the garden city Cantabrians have been lining up at testing stations this week. An additional site was set up at Princess Margaret Hospital catering to the surge in demand.
It was revealed the two health workers had visited a Countdown supermarket and chemist shop while infectious with people who had been in the stores at the same time urged by health officials to get a test.
Yesterday the Unite Against Covid website urged people, including those in Christchurch, to stay home if sick, use the dedicated government tracer app to record movement and wear a mask on public transport.
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