Prof John Potter*
Elimination has been an effective strategy for New Zealand in the management of the COVID-19 pandemic virus (SARS-CoV-2). Most other countries have not pursued this goal and are ignoring the opportunity even now. SARS-CoV-2 is not manageable by the influenza playbook; its longer incubation period makes tracing and isolation more practicable and puts elimination within reach. There is one additional argument in favour of elimination: the longer the highly infectious SARS-CoV-2 virus circulates in the human population, the greater is the likelihood that it will find a host among other animal species and that these will become a reservoir capable of transmission back to humans.
Prof Nick Wilson, Prof Michael Baker, Prof Martin Eichner (*author details)
In this new study, we estimated the risk of COVID-19 outbreaks associated with air travel from Australia (with a low prevalence of COVID-19 infection) to NZ. We found that the combined use of exit and entry screening, two PCR tests (on days 3 and 12 in NZ), mask use and contact tracing, reduced the risk from one outbreak every 1.7 years (no interventions) to every 29.8 years (95% uncertainty interval: 0.8 to 110). This risk is similar to that achieved by the current system of 14 days quarantine, at one outbreak every 34.1 years (0.86 to 126). In conclusion, multi-layered interventions can markedly reduce the risk of importing the pandemic virus into a COVID-19-free nation like NZ. Whatever approach is chosen, careful management and evaluation will be needed.
Prof Nick Wilson, Dr Jennifer Summers, A/Prof George Thomson, Dr Amanda Kvalsvig, Dr Matt Boyd, Prof Michael Baker
Here we present five key reasons for why the NZ Government should establish an official inquiry into the COVID-19 pandemic response. Such an inquiry could identify lessons for the near future (eg, for pandemic control if border control failures occur) but also identify lessons for the organisation and resourcing of public health more broadly. Fortunately, NZ has a fairly solid track record of official inquiries that have resulted in improved systems that advance public safety and public health.
Prof Nick Wilson, Dr Matthew Parry, Dr Ayesha Verrall, Prof Michael Baker, Prof Martin Eichner (author details*)
This blog details a recent modelling study we conducted. In it we estimated that it would take between 27 and 33 days of no new detected cases of COVID-19 for there to be a 95% probability of epidemic extinction in NZ (at around current testing levels). For a 99% probability of epidemic extinction, the equivalent time-period was 37 to 44 days. So now the country urgently needs the Ministry of Health to provide an official definition of elimination and to upgrade the data on its website so that the public, the media and researchers can monitor progress towards achieving the goal.
Dr Jaijus Pallippadan-Johny1, Dr John McDermott2, Rodney Jones1 and Michael Duddin1 (1 Wigram Capital Advisors, Auckland; 2Motu Economic and Policy Research, Wellington)
In this blog, we introduce our modelling approach to estimating the transmissibility of the SARS-CoV-2 virus, the cause of the COVID-19 pandemic. We demonstrate the usefulness of the Wallinga model for the calculation of the effective reproduction number and show the major impact of the lockdown on containing the pandemic in New Zealand.