Director general of health Dr Ashley Bloomfield says there is a low chance that the "horse has bolted" on the latest Covid-19 community case - a health worker looking after foreign fishermen in managed isolation.
The worker, a woman in her 50s on duty at the Sudima Hotel at Christchurch airport, tested positive this week and is currently in isolation at home. She has mild symptoms and is being monitored daily.
Other Sudima staff working on the same shift are being contacted and will be tested if necessary.
One of her household contacts, a Cashmere High School student, is in isolation and has tested negative.
Parents at Cashmere have been told that the school community don't need to be tested or to self-isolate unless they have any symptoms.
"It is business as usual at the school today," Bloomfield said.
Bloomfield said the risk of spread at the Cashmere school was low. "There's no sense that any horse has bolted here."
Worker's Countdown visit
Video footage at the Countdown on Colombo St, which the worker visited, is being reviewed, he said.
A low number of people were at Countdown at the same time as her, he said, and the risk of spread at the Countdown and at the school was low.
Currently there were no other places of interest where spread might have occurred.
He wouldn't say he was disappointed the woman went to Countdown while symptomatic because he didn't know all the details - but the broad message was for people who felt sick to stay at home.
There was no asymptomatic testing of Countdown workers at this stage.
Bloomfield likened the situation to the Jet Park nurse who went to three Les Mills exercise classes and the port worker-related case who went to the North Shore pub - neither of which led to further infections.
Incoming Covid-19 Response Minister Chris Hipkins said the Sudima health worker was potentially infectious for a "small window of time", and he thanked the worker for getting tested when she became symptomatic.
He implored Kiwis to use the NZ Covid Tracer app as it gave officials a "real head start" in cases like this; a push notification has been sent out to people who were at the Countdown at the same time as the worker.
"We will see cases emerge from time to time. The key is to identify them early and to contain them."
He said people had become too complacent and urged everyone to scan QR codes, stay home if sick, and to wear masks on public transport - even though mask-wearing is not mandatory.
Businesses were enjoying level 1 freedoms, and they had a role to play by making sure their QR codes were prominently displayed and encouraging their customers to scan it.
The case means the foreign fishermen's stay will be extended for 24 hours while a full picture of the situation is ascertained.
The international seamen were brought in to work on New Zealand fishing boats. They are from Russia and Ukraine.
There are three different lineages of the virus among the dozens of mariners who have tested positive. None had been in New Zealand prior to the arrival of the group.
The next tranche of overseas mariners, due to arrive next week, has also been delayed.
Bloomfield said the source of infection for the health worker at the Sudima was still being looked at.
"It's possible we will find other cases."
He pushed back on Otago University public health expert Professor Nick Wilson's description that this was a border failure.
"This is another example of the system working well to protect our border," Bloomfield said.
Over 60,000 people had been through managed isolation, and Bloomfield said the low number of infections leaking into the community showed how well the system was working.
Hipkins added there was no such thing as a 100 per cent foolproof system, and the system had been audited twice and was continually improved.
He said the latest audit by Heather Simpson and Sir Brian Roche would be released.
Wilson has criticised the Sudima situation where two mariners were sometimes sharing a room.
But Bloomfield said that was not unusual, as family members also shared a room where that was deemed safe enough.
Four cases in managed isolation
Bloomfield said today's other four cases were in the Jet Park quarantine facility.
• One case arrived on October 19 from Kabul via Dubai and has tested positive at around day 12.
• One case arrived on October 21 from London via Doha and Brisbane and has tested positive at around day 12.
• One case arrived on October 29 from the US via Sydney and has tested positive at around day 3.
• One case arrived on October 29 from New York via Doha and Brisbane and has tested positive at around day 3.
Of the four people who tested positive in managed isolation today one of the cases is a baby boy under the age of 1.
Bloomfield said officials were looking at the cases testing positive on day 12 to ensure there was no cross-contamination inside a managed isolation facility.
Yesterday there were 2455 tests conducted. There are currently 75 active cases in New Zealand.
There was a booking system in place for rooms in managed isolation, and space was tight. Hipkins said people will have to rearrange their travel dates, and that will disappoint some people, but safety was the priority.
People could apply for exemptions, but the bar was very high, he said.
Hipkins said the Auckland August cluster was now officially closed. It involved 179 cases.
"Auckland is now back to enjoying the freedoms we all enjoy at alert level 1. But we are not at alert level none. We need to continue to use the Covid Tracer app."
Worker at Chch isolation hotel tests positive
Last night the Ministry of Health confirmed that a worker at the Sudima Christchurch Airport hotel had tested positive for Covid-19. The worker visited a supermarket on Saturday while symptomatic.
It is at least the fifth, and likely the sixth, border failure since the start of August, prompting public health experts to tell the Government to up its game.
The Sudima is being used as a managed isolation facility, and is where hundreds of Russian and Ukrainian mariners are being housed - including dozens who have tested positive for the virus.
The infected worker was tested on Thursday as part of routine testing for border-facing workers. The worker tested negative, but on Saturday they started feeling unwell and were tested again on Sunday, with a positive test returned yesterday.
Despite their symptoms, they went to the Countdown supermarket in Colombo St in Sydenham on Saturday, which has since been deep-cleaned.
The Canterbury District Health Board has also sent a letter to Cashmere High School parents today confirming a student was a close contact of the infected worker.
The student has tested negative and is isolating at home. The school has been advised that the risk is low and students and staff do not need to be tested or self-isolate unless they have symptoms.
This latest outbreak is at least the fifth, and likely the sixth, border failure in recent months.
The other cases are:
• The Auckland cluster in August which had 179 cases. The source has never been determined but a border failure is likely. Genome sequencing found no link to existing cases in managed isolation but only about 20 per cent of those cases had been successfully sequenced at the time the outbreak was detected.
• A maintenance worker at Rydges Hotel who is thought to have caught Covid-19 after using a lift shortly after an infected overseas returnee.
• A nurse who caught Covid-19 while working at the Jet Park quarantine facility, and who sparked concern after she went to three Les Mills fitness classes while potentially infectious.
• An overseas arrival who is thought to have caught Covid-19 after touching the lid of a rubbish bin they shared with an infected person while in managed isolation at the Crowne Plaza in Christchurch. They tested negative on day 12 and left the facility, flying to Auckland on a chartered flight. They sat behind another overseas returnee on the flight who became ill, and they both subsequently tested positive.
• The port worker who is thought to have caught Covid-19 while working on the Sofrana Surville ship while it was in Auckland. Eight foreign crew members from the Philippines joined the ship on the same day the port worker was on board. The Government has now changed the rules for foreign ship crew, who will all be tested on arrival in New Zealand regardless of the time spent in transit.
There are several infection prevention measures in place to stop border cases leaking into the community, including the use of personal protective equipment, deep-cleaning of rooms and shared areas, daily health checks, and testing of overseas arrivals on day three and day 12 of their stay.
But public health expert Professor Wilson from the University of Otago said the Government needed to "up its game".
"This is an area that needs an urgent review. It's not adequate that workers are being placed at risk," Wilson told RNZ.
"We've had a nurse infected, a maintenance worker, a port worker. These are system failures because we should be stopping all cases at the border."
Wilson suggested stronger border controls including pre-flight testing, purpose-built facilities with better ventilation, as well as more facilities outside Auckland where the population was more concentrated .
"Basically we're having border control failures every two weeks and we could end up with another Auckland August outbreak if we don't improve."
Today Covid-19 testing sites are opening up in Christchurch, with a queue forming this morning at a testing facility near Christchurch airport.
The latest case comes as Prime Minister Jacinda Ardern has given Hipkins sole ministerial responsibility for the Covid-19 health response.
She unveiled her Cabinet line-up yesterday, which includes teams of ministers looking after Health and the Covid-19 economic recovery.
They will be sworn in on Friday.