Coronavirus: Prime Minister Jacinda Ardern, Michael Baker agree COVID-19 cases connected to managed isolation always a risk

Both the Prime Minister and a leading epidemiologist say community COVID-19 cases connected to managed isolation facilities are to be expected, but the system is built to respond.

The Ministry of Health on Monday night informed the country that a staff member working in a Christchurch managed isolation facility had been infected with COVID-19. 

The person was tested as part of routine testing for facility staff and returned a negative test on Thursday. However, on Saturday, they developed symptoms and sought another test on Sunday, which has come back positive. They're now in isolation and report isolating as soon as they developed symptoms. 

A Countdown on Colombo St in the Christchurch suburb of Sydenham was deep cleaned on Monday night. It's reported the infected individual visited the supermarket on Sunday. The store is expected to open as usual at 8am on Tuesday.

Speaking about the case while on a Facebook Live, Prime Minister Jacinda Ardern said there was a system in place to find these cases. Such processes, like routine testing, were necessary "to manage these situations because we have to expect them when people are working around COVID."

"Our system is utterly built for managing a situation where people who may be attached to our MIQ systems themselves find themselves positive with COVID," she told her followers.

"Our whole system is built for that, that's why we have an ongoing testing regime. It's why, particularly our people who work in our MIQ keep very, very good records of where they've been and who they've been in contact with.

"They are very aware of their health status, so if they feel unwell they're very cautious about getting tested straight away and being isolated straight away."

She told Kiwis they can feel "assured" a system is in place to catch the cases and it is "a good one we are constantly refining and working on".

Dr Michael Baker, a professor of public health at the University of Otago, said with thousands of people moving through the managed isolation facilities and hundreds of staff, transmission to a worker is a risk. 

"It's a risk that we know can happen... That's the nature of the disease. It is very infectious," he told Newshub.

"We will occasionally see cases like this where staff have been infected."

Dr Baker said the staff member did the right thing by keeping alert of their symptoms and seeking out a test when they became unwell. 

"That's really good news. The other side of that is that we shouldn't have any staff getting infected. Whenever this happens, we need to investigate very carefully to see what went wrong so we can prevent it happening again."

He wants everyone in the Christchurch region to be cautious and aware of their own symptoms. It's critical, he said, that anyone who does feel unwell, stays home. 

The managed isolation facility where the worker is believed to have caught the virus is the same site that a group of international mariners are staying, many of whom have tested for COVID-19.

The Ministry of Health said on Monday that the first lot of the group were due to complete their stay in the facility on Tuesday morning. However, they will now remain there for at least another 24 hours "as an additional precautionary measure". 

"Those precautionary measures have included additional tests – up to four tests for some individuals - and an already lengthened stay in managed isolation."

Dr Baker said it's good to see authorities pause and consider if the system is working and if there is a "chain of transmission" that hasn't been "closed down properly".