Reports from Covid-19 Modelling Aotearoa


Our Covid-19 modelling influences policy decisions, so we make it publicly available as soon as we can. All of our published work is assessed by our fast and committed peer review team to enable a degree of scientific certainty within the parameters of rapid change.

Modelling scenarios for changing COVID-19 isolating behaviour and transmission

This report presents advice delivered to the NZ Ministry of Health in December 2022. It was prepared in response to requests for modelling advice around how COVID-19 case numbers and hospitalisations might be affected by policy changes enacted at different dates in the future, as well as a new variant of concern becoming dominant in November.

Commuter Count: Inferring Travel Patterns from Location Data

The spread of transmissible disease is known to be tightly correlated with population movements, so we wanted to develop a means by which to infer daily travel patterns and thereby predict which people were likely to come into contact with one another during the course of a normal working day. 

We made use of aggregate spatio-temporal data collected by telecommunications networks. This data provides total counts of contactable cell phones in over 2000 small geographical regions per hour, and cannot reveal any personal information about individual users. 

This work was largely completed while Aotearoa New Zealand was at lockdown levels 3 and 4 and mobility restrictions were in place.

Quantifying the effect of a change in case isolation settings

This memo was provided to the NZ Ministry of Health on November 16th, 2022 in response to a request for rapid advice on November 15th, 2022. The memo presents results for specific scenarios of interest: case isolation of 7 days or 5 days with no test-to-release, and 5 days with test-to-release. The method and results used here are from a previously published, internally reviewed report.

Modelling Covid-19 dynamics in New Zealand August 2022 to February 2023

Since July 2022, Covid-19 Modelling Aotearoa have been using a compartment-based ordinary differential equation (ODE) model to simulate the spread of Covid-19 in Aotearoa New Zealand.

This age-structured model includes waning of vaccine-derived and infection-derived immunity, immune evasion of new Omicron subvariants, age-dependent hospitalisation and death rates, and changes in transmission resulting from behavioural and policy changes. The model is calibrated to data on Covid-19 cases, hospitalisations and deaths using an approximate Bayesian computation (ABC) method. 

The model has been periodically updated to reflect the changing transmission and immunity landscape in New Zealand.

Modelling the effect of changes to the COVID-19 case isolation policy

COVID-19 Modelling Aotearoa used a mathematical model to investigate the potential impact of shifting from mandatory COVID-19 case isolation to case isolation guidance on the number of infections, hospital admissions, and deaths over the next 6 months.  Irrespective...

Modelling Aotearoa New Zealand’s COVID-19 Protection Framework and the transition away from the elimination strategy

Covid-19 Aotearoa developed an age-structured model for the Delta variant of SARS-CoV-2 including the effects of vaccination, case isolation, contact tracing, border controls and population-wide control measures. We use this model to investigate how epidemic trajectories may respond to different control strategies, and to explore trade-offs between restrictions in the community and restrictions at the border.

FluTracking incidence calculation methods

This report details the methods used for calculating the estimated weekly incidence of Covid-19-like and influenza-like illness in Aotearoa New Zealand, using data from the FluTracking weekly survey.

Inter-regional movement and contagion risk analysis August 2021

We use a range of data sources and analytic approaches to estimate the number of movements between regions of Aotearoa and to give some estimates of the risk of transmission of Covid-19 to regions outside of Auckland, during the early stages of the August 2021 outbreak.

A Covid-19 vaccination model for Aotearoa New Zealand

We use a mathematical model to estimate the effect of Aotearoa New Zealand’s vaccine rollout on the potential spread and health impacts of Covid-19 and the implications for controlling border-related outbreaks.