Objectives:

The main purpose of this paper is to develop a model that can be used as the basis for policy advice on border restrictions and control measures in response to outbreaks that may occur during the vaccination roll-out.

Method:

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

We consider a range of scenarios at different stages in the vaccine roll-out, including an unmitigated epidemic and contained local outbreaks. This work is intended to form a foundation for further COVID-19 vaccination modelling in New Zealand that will account for additional demographic variables.

Findings:

Our results show that, under baseline vaccine effectiveness assumptions and with R0 = 4.5, vaccination of over 80% of the population will likely be necessary to reach the population immunity threshold, defined as a reproduction number that is less than 1 in the absence of other interventions. This would almost certainly require vaccination of at least some under 16 year olds. If R0 = 6 (which could represent a highly transmissible SARS-CoV-2 variant such as Delta), population immunity would require approximately 97% of the population, something which is unlikely to be achievable in practice.

Conclusion:

Our results suggest that, until we get close to the population immunity threshold, a major public health response that included significant interventions would still be required to control any resurgent outbreaks and prevent a major epidemic.

[Full paper] (https://www.tepunahamatatini.ac.nz/2021/06/30/a-covid-19-vaccination-model-for-aotearoa-new-zealand/)