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New community case of COVID-19 – Expert Reaction

There is one new community case of COVID-19 in New Zealand, Dr Ashley Bloomfield announced today.

The person is a man who works on ships that have been at the Ports of Auckland and Port Taranaki. The man returned returned a positive COVID-19 test result on Saturday. Dr Bloomfield said there is no evidence of community transmission at present.

The SMC asked experts to comment on the announcement. 

Associate Professor Siouxsie Wiles, School of Biological Sciences, University of Auckland, comments:

“The new case of COVID-19 outside of managed isolation and quarantine is a person who works onboard vessels which come in from overseas. This means it is unlikely this is a case of community transmission but is a case in the community in a border worker who we know are at risk, even though they routinely wear PPE. It is most likely that the person became infected after being on an international vessel to carry out maintenance sometime in the last two weeks. Genomic sequencing may help further identify the source of his infection. He has previously tested negative during routine testing but developed symptoms on Friday. Importantly, he immediately got tested and went into isolation. This will have limited the time he was in contact with others in the community while infectious.

“This latest case is both an example of our border controls working as intended and the tricky nature of the virus. While using PPE helps to limit the spread of COVID-19, it is not an impenetrable defence. Hence the routine testing, and border workers seeking a test if they feel unwell. I’d like to thank the worker for getting tested so fast, as this will have limited the risk of the virus spreading any further.

“In his briefing, the Director-General of Health mentioned the ‘Swiss Cheese Model‘. This was first described by Prof James Reason of the University of Manchester, UK, over 20 years ago. The ‘Swiss Cheese Model’ describes how the barriers and safeguards put in place within a particular system are not impenetrable – they have holes in them, like some types of Swiss cheese. A hole in one layer of defence isn’t a disaster if there are lots of other layers of defence to fall back on. So think of PPE as one layer of Swiss cheese, and routine testing of border workers another. But just as important is people getting tested as soon as they develop any symptoms and going into isolation. ”

No conflict of interest.

Professor Michael Baker, Professor of Public Health, University of Otago, Wellington:

“This newly identified COVID-19 case in a port worker is important as it appears to be the first New Zealand case linked to a seaport and shipping.

“It is also continuing a pattern we are seeing of occasional cases and outbreaks linked to breaches in border biosecurity. Since the large Auckland August cluster, we have seen three small ‘outbreaks’ linked to MIQ facilities, two in Auckland and one from Christchurch, and now this case linked to a seaport. Given the COVID-19 pandemic is continuing to intensify globally, we can expect to see a continuing risk of these kinds of breaches.

“The first priority is of course to investigate and control this potential outbreak as quickly as possible. But we also need to thoroughly investigate this case to identify how they became infected so that we can avoid this error happening again.

“Seaports have received less attention than airports, but are obviously an area of vulnerability for NZ, as this case appears to show.

“The rapid identification and management of this case suggests that all of the testing and contact tracing systems are working well in NZ.

“This case also did all the right things in terms of seeking testing as soon as he developed symptoms.

“It is still too early to know if any of his contacts were infected. However, the information available at this stage suggests that this outbreak should be contained very effectively.

“The risk of COVID-19 outbreaks from shore leave by shipping crews was assessed in a recently published modelling study which also shows how this virus can be imported through ports.”

No conflict of interest.

Professor Michael Plank, Te Pūnaha Matatini and University of Canterbury, comments:

“The Ministry of Health today announced a new case of Covid-19 in a man who works at Ports of Auckland and Ports of Taranaki. This case is an example of our testing system working as it designed to. The man was tested promptly after developing symptoms and his close contacts were quickly traced, tested and isolated. The Covid tracer app may be used to notify people who have scanned into places the man visited recently. The risk of onward transmission is relatively low, although anyone with symptoms should still stay at home and get tested.

“Although this is New Zealand’s first community case of Covid-19 in over two weeks, there is no evidence so far that it was caused by community transmission. The most likely scenario is that the man was infected while working on a ship. Genome sequencing is currently underway and results are expected in a few days. These will help establish whether or not there is a link to the recent Auckland cluster.

“This case reinforces the importance of regular testing of all border-facing workers. Modelling shows that testing weekly rather than fortnightly significantly reduces the risk of an outbreak starting from a border worker. This case is also a reminder that, although we have eliminated community transmission of COVID-19, that doesn’t mean it won’t come back. To prevent another outbreak, everyone needs to use the Covid tracer app to record their movements and if they become unwell, stay home and get tested.”

Conflict of interest statement: I am partly funded by MBIE for research on mathematical modelling of COVID-19.

Dr Amanda Kvalsvig, Senior Research Fellow, Department of Public Health, University of Otago, Wellington, comments:

“This new case is not unexpected, given how high infection rates are around the world. The person concerned has done the right thing in being tested straight away and the public health response has been thorough. I hope more information will emerge about exactly how this person became infected, to guide future precautions around ports, and in particular to protect people who live in those places. 

“This case illustrates the risk of having minimal Covid-19 measures in place in New Zealand communities while the pandemic is still accelerating elsewhere. If this person had travelled by bus instead of by car during the time when he was likely infectious but had no symptoms, he could have infected a large number of people. There are several overseas examples of bus travel as a ‘superspreader’ event, which is unsurprising when you have a large number of people sitting close together sharing the same air.

“We can’t afford to rely on good luck to stay safe in a pandemic. The Government needs to re-examine the evidence on mask wearing urgently, and build mask use into public transport settings from Alert Level 1 on up. There may also be value in requiring some individuals to wear a mask while in transit through communities if they’re in a high-risk occupation, and this possibility should be explored in the light of the current case.”

No conflict of interest.

Professor Shaun Hendy, Director of Te Pūnaha Matatini, comments:

“This case has been detected in someone with a clear connection to the border, so the risks of a significant community outbreak are low. Nonetheless this is a reminder that we all need to be vigilant. We need to keep getting tested if we develop any of the symptoms of COVID-19, keep up our use of the app, and remember to take our basic hygiene precautions.”

Conflict of interest statement: Te Pūnaha Matatini is funded by the TEC, but is also currently working under an MBIE contract to supply COVID-19 modelling to government.