New Zealand Should Start Testing Health- and Aged Care Workers for SARS-CoV-2

April 17, 2020

There are strong indications that New Zealand will soon be moving down from Alert Level 4 – ‘full lockdown’ – to lower alert levels. In my view it would be a serious mistake to do this without instituting a substantial SARS-CoV-2 testing program for health- and aged care workers. I’ll briefly explain why.

For background: we know that New Zealand’s ‘lockdown’ period has greatly reduced the number of new cases of COVID-19 – here’s a simple chart I made using Ministry of Health data showing daily new cases.


This represents an apparent success of the New Zealand policy of not just ‘flattening the curve’ but attempting to reduce the incidence of COVID-19 such that only a small number of cases remain in the country. The government hopes that if this can be achieved, in combination with strict border controls, then the few remaining new cases can be contained using self-isolation and contact tracing, preventing the kind of broader community outbreaks we have seen elsewhere in the world.

Across this period, the government has also significantly increased its testing capacity, and the number of tests typically carried out each day. Here’s a chart I’ve taken from Newsroom, showing daily tests carried out.


The government has nevertheless been reluctant to test people not showing respiratory symptoms of COVID-19. In early days of the pandemic, NZ government guidelines suggested that people should only be tested if they showed symptoms of COVID-19 and were either contacts of a known case of COVID-19 or had recently travelled overseas. At the end of March, the government broadened its guidelines such that anyone showing respiratory symptoms could be tested, regardless of travel history or contacts. Only in the last few days has the government begun testing people without symptoms, using testing centres in specific, targeted locations, to collect more data on the possibility of community spread in potential COVID-19 ‘hotspots’.

This expansion of testing is good, and long overdue. However, in my view the government is making a serious mistake by not also implementing a large-scale randomised testing program of health- and aged care workers. This is for three broad reasons.

First: Health and aged-care workers are essential workers who by the nature of their work are much more likely than most Kiwis to be exposed to the virus. Cases of COVID-19 among health- and aged-care workers can therefore potentially function as useful ‘sentinels’ for detecting broader community transmission, without the waste of resources (and the same degree of likelihood of false positives) associated with mass community testing.

Second: To state the obvious, health- and aged care workers are much more likely than most Kiwis to transmit the virus to vulnerable individuals, because their job is to care for people who are much more likely than most Kiwis to be vulnerable to COVID-19. Identifying infection among health- and aged care workers early is therefore likely to have a high potential payoff in terms of lives saved.

Third, and relatedly: The modelling of virus spread across New Zealand (such as that carried out by Te Pūnaha Matatini or commissioned by the Ministry of Health) has focussed on the population of the country as a whole. However, we of course know that there can be localised outbreaks or ‘clusters’, where the virus is very widespread within a specific subcommunity. The Rosewood rest home is one such cluster; as of writing, seven of New Zealand’s eleven COVID-19-related deaths have occured within this cluster.

It is potentially disastrous when a hospital or aged care institution – or even worse the hospital or aged care system as a whole – becomes such a ‘cluster’, within which the virus is widespread. We know from other countries’ experiences that the impact of COVID-19 is most disastrous when the healthcare system is pushed beyond capacity, resulting in an immediate increase in the death rate from COVID-19, as well as many other negative health impacts associated with care not being provided for other conditions. In other countries, this scenario has typically occurred because the number of COVID-19 cases in the broader community has exceeded hospitals’ capacity. However, the spread of SARS-CoV-2 within the hospital system itself will of course also reduce hospitals’ capacity, as well as increase the risks to all patients within the system. The same applies to aged care facilities, which by their nature concentrate people in the demographics most vulnerable to the virus.

It is possible to imagine a scenario, for example, in which broad community incidence of COVID-19 remains very low, but COVID-19 is widespread within a hospital or hospitals, and this scenario would have a disproportionate negative impact on both New Zealand’s COVID-19 death rate, and on our ability to manage the virus, regardless of the success of the rest of the government’s COVID-19 strategy. Moreover, it would be difficult to suppress the virus, in this scenario, because hospitals are by their nature essential services which cannot be ‘locked down’ without very severe health consequences for the communities they serve.

For these reasons, it is worth adopting a highly precautionary approach to ensuring that SARS-CoV-2 does not spread within the health- and aged care systems. These institutions are a ‘weak point’ in our ability to deal with COVID-19. Given the extreme measures we have taken to combat COVID-19 (including near-complete closure of the country’s borders, and level 4 alert measures nationwide) it seems reckless and irrational for the government to fail to implement a much less extreme measure – widespread randomised testing of health- and aged care workers – that could have a disproportionate impact on our ability to successfully manage COVID-19 and its consequences. The government should implement such a testing policy as a matter of urgency.

One Response to “New Zealand Should Start Testing Health- and Aged Care Workers for SARS-CoV-2”

  1. […] by repeated testing; it is in fact extremely rational to adopt a policy of broader testing, as I argued in an earlier post; and none of this makes any sense when you’re talking about a process that has specifically been […]

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