Abstract
We use a stochastic branching process model, structured by age and level of healthcare access, to look at the heterogeneous spread of Covid-19 within a population. We examine the effect of control scenarios targeted at particular groups, such as school closures or social distancing by older people. Although we currently lack detailed empirical data about contact and infection rates between age groups and groups with different levels of healthcare access within Aotearoa New Zealand, these scenarios illustrate how such evidence could be used to inform specific interventions.
We find that an increase in the transmission rates among children from reopening schools is unlikely to significantly increase the number of cases, unless this is accompanied by a change in adult behaviour. We also find that there is a risk of undetected outbreaks occurring in communities that have low access to healthcare and that are socially isolated from more privileged communities. The greater the degree of inequity and extent of social segregation, the longer it will take before any outbreaks are detected.
A well-established evidence for health inequities, particularly in accessing primary healthcare and testing, indicates that Māori and Pacific peoples are at a higher risk of undetected outbreaks in Aotearoa New Zealand. This highlights the importance of ensuring that community needs for access to healthcare, including early proactive testing, rapid contact tracing and the ability to isolate, are being met equitably. Finally, these scenarios illustrate how information concerning contact and infection rates across different demographic groups may be useful in informing specific policy interventions.
Executive summary
- We develop a structured model to look at the spread of Covid-19 in different groups within the population. We examine two case studies: The effect of control scenarios aimed at particular age groups (e.g. school closures) and the effect of inequitable access to healthcare and testing. These scenarios illustrate how such evidence could be used to inform specific policy interventions.
- An increase in contact rates among children, which might result from reopening schools, is on its own unlikely to significantly increase the number of cases. However, if this change in turn causes a change in adult behaviour, for example increased contacts among parents, it could have a much bigger effect.
- We also consider scenarios where outbreaks occur undetected in sectors of the community with less access to healthcare. We find that the lower the contact rate between groups with differing access to healthcare, the longer it will take before any outbreaks are detected in any groups who experience unequitable access to healthcare, which in Aotearoa New Zealand includes Māori and Pacific peoples.
- Well-established evidence for health inequities, particularly in accessing primary healthcare and testing, indicates that Māori and Pacific communities in Aotearoa New Zealand are at higher risk of undetected outbreaks. The government should ensure that the healthcare needs of Māori and Pacific communities with respect to Covid-19 are being met equitably.