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COVID-19 testing at the border – Expert Reaction

The Government has announced new changes to how it tests for COVID-19 in people who work near New Zealand’s borders.

The new testing strategy includes regular health checks and asymptomatic testing of all border-facing workers, as well as regularly testing people who are exempt from quarantine, such as New Zealand-based air crews.

The SMC asked experts to comment on these changes.

Dr Joshua Freeman, Clinical Director Microbiology and Virology and Acting Clinical Director Infection Prevention and Control, Canterbury District Health Board, comments:

The latest COVID-19 testing strategy announced today by David Clark is a mixed bag. It certainly makes sense to increase systematic testing of those working at our borders and those exempted from quarantine.

“However, the suspect case definition used to determine who should get tested more generally, is overdue for change and is no longer fit for purpose. Testing everyone presenting to hospital with a runny nose or sore throat is, in our experience, having negative downstream consequences on the delivery of healthcare. Several months ago when the current suspect case definition was introduced, there was much uncertainty about community transmission, and it made sense to test everyone presenting to hospital or general practice with a sore throat, runny nose, or increased shortness of breath. However, in the current environment where we know the probability of undetected chains of community transmission is vanishingly low, such broad and undirected testing has marginal benefit, leads to substantial waste, and in our experience, carries risk of harmful flow-on effects.

“Harmful flow-on effects occur because a large proportion of patients currently presenting to hospital for a variety of unrelated conditions incidentally meet the COVID-19 case definition due to non-specific symptoms such as a sore throat, runny nose or shortness of breath due to unrelated health conditions.  In accordance with Ministry of Health advice, these patients tend to be managed in single rooms with full PPE until test results become available. This leads to unnecessary consumption of PPE and laboratory resources, but more importantly, slows patient transfer to specialty wards where they can be managed most appropriately. These delays are due to lack of immediate availability of single rooms due to high demand.

“Anecdotes of delays to receiving necessary investigations and treatment are also of concern. Delays in investigations may result, for example, due to the logistics of arranging special transport and cleaning protocols required for those awaiting COVID-19 test results. Similar concerns of unintended consequences are being reported by colleagues in general practice.

“Coinciding with this announcement, the common cold virus (known as rhinovirus) appears to be increasing in the community, causing people to get runny noses and scratchy throats just as it does every year. This appears to be contributing to a surge in demand for swabbing at community-based testing centres.

“These problems could be addressed by adding a requirement for at least one epidemiological risk factor to the suspect case definition such as:

  • Close or casual contact with a confirmed case of COVID-19
  • OR return from overseas travel or  close or casual contact with a returned overseas traveller within 14 days of travel/contact
  • OR international flight crew, airport staff, border control staff, quarantine hotel staff, port workers or their close /casual contacts

“Changing the definition doesn’t preclude systematic surveillance testing in the community, but such testing should be in the context of a carefully designed community surveillance programme and – in order to avoid potentially harmful disruption to healthcare delivery – should not be linked to the suspect case definition.”

No conflict of interest.

Associate Professor Lynn McBain, Head of Department of Primary Health and General Practice, University of Otago, Wellington, comments:

“The enhanced testing regime for those at higher risk as listed – border workers, those working in the isolation and quarantine facilities, and international air and maritime crews is a good step forward. The border is clearly the weakest point in the COVID-19 reduction / eradication strategy. This is particularly so now that the number of worldwide cases are continuing to increase at a high rate.

“The statement that: ‘Anyone presenting to primary or secondary care with symptoms consistent with COVID-19 will be offered testing even if they have no history of international travel or contact with travellers’ is not new. This is what is happening currently as primary and secondary services are testing large numbers of people.

“As most New Zealanders return to the new normal of Level 1 – work , school and day care as well as social gatherings, there is an increasing number of low-level respiratory infections (not influenza at this stage). This means that there will be increasing numbers presenting for testing as the current case definition for COVID-19 is very broad. ‘Any acute respiratory infection with at least one of the following symptoms: cough, sore throat, shortness of breath, coryza, anosmia with or without fever.’

“I agree with community testing  – however there is a risk that the numbers of tests required to test all of these with any of these listed symptoms will mean that health services are diverting staff and resources to testing and away from usual care.

“A way forward might possibly be looking at alternative modelling for community testing  – perhaps sentinel testing, or other ways to have continued confidence in the lack of community spread – but not needing to test everyone with a runny nose or sore throat. There is not a simple solution.”

Conflict of interest statement: Dr McBain owns a general practice in Wellington.

Dr Nikki Freed, Senior Lecturer in the School of Natural and Computational Sciences, Massey University, comments:

“I think the recent cases at the border underscore how vigilant New Zealand will need to be in terms of testing and surveillance to keep COVID-19 case numbers low. The new changes announced today to the COVID-19 testing strategy are a strong move in the right direction.

“There are several important steps in these new changes which will help the Ministry of Health catch cases at the border, and importantly, find any COVID-19 cases that might be circulating in the community. Two of these steps stand out to me. The first is setting a low bar for testing, so that anyone presenting with symptoms is able to get tested, and second is identifying groups who are under tested. Knowing where the ‘holes’ are in community testing is an important step to making sure the surveillance is working.

“Finally, I think the Ministry of Health has done a very good job of adjusting and updating the testing strategy to ensure New Zealander’s remain safe and to keep COVID-19 levels at a global low.”

Dr Freed has been awarded HRC funding to research rapid diagnosis and genome sequencing to follow the coronavirus outbreak.

No conflict of interest.

John Mackay, Technical Director at dnature diagnostics & research Ltd, comments:

“The use of multiple tests is a good strategy to avoid concerns that a recently-infected person will not have enough virus present to return a positive test – thereby greatly reducing the risk of infected people returning a negative test result at a single point in time, i.e., reducing the ‘false negatives’.

“Equitable testing is important – because COVID-19, influenza, and other respiratory diseases are not equitable, affecting Māori and other New Zealand groups to an increased extent.

“Despite flu levels being at low levels (lockdown was not just good for lowering COVID levels!), influenza levels are expected to rise and new tests in development by New Zealand researchers are being designed to detect and discriminate both these illnesses, when symptoms may appear similar. In the meantime, New Zealand continues to have good supplies of the virus testing reagents needed.”

John Mackay has been awarded HRC funding to research rapid 15-minute diagnostics for distinguishing COVID-19 from influenza.

No conflict of interest.