08 Nov 2021
Work Package 2: Subpopulations – First Nations
Due to different community structure, limited access to care, and historical inequities, the impacts of COVID-19 are anticipated to be disproportionately greater among remote-living Aboriginal and Torres Strait Islander Australians than in non-Indigenous urban populations. Protecting these communities is a national priority. Pre-emptive and reactive public health measures including vaccination and nonpharmaceutical interventions can markedly improve health outcomes in remote Indigenous communities.
This work assesses the effectiveness of a variety of strategies based on both vaccination and non-pharmaceutical interventions to minimise the impact of COVID-19 on remote Indigenous communities.
Key findings:
- High levels of pre-emptive vaccine coverage can substantially reduce COVID-19 transmission and health impacts in remote Indigenous communities.
- Of the strategies recommended in the current remote outbreak response guidelines, a policy that assumes relocation of contacts of cases to a hospital or safe location outside the community for the duration of quarantine is associated with improved outbreak control and lower disease burden.
- Reactive vaccination is a useful adjunct to community engaged and led outbreak response, and can reduce health impacts, particularly in larger communities with low initial vaccine coverage.
- Providing access to effective treatments will further promote health outcomes, particularly where clinical access is limited.
Outside the scope of this analysis/future work:
This analysis focuses on transmissions taking place within remote communities following an initially undetected COVID-19 case in the community. It does not consider:
- The benefits of public health responses in the broader Australian population on reducing introductions into remote communities.
- The role of transmission within one remote community in triggering introductions into other communities.
- The cost or cost effectiveness of different response measures.
Limitations:
- The predictions of a given scenario are not relevant if there are not enough resources to implement the simulated intervention (e.g. in modelling the impact of isolation of contacts, we have not considered whether locations to isolate are available).
- The exemplar communities we consider are not intended to match any specific community. Many variables will differ from community to community. The analysis gives qualitative guidance of the relative impact of different interventions in small, medium, and large remote communities, but it should not be interpreted as an exact prediction for any community.
- There is not enough data to accurately estimate severity by age in remote communities. This work has assumed that those under 20 have outcomes similar to the general Australian community. Those 20 and over have outcomes similar to those 10 years older in the general Australian community (resulting from faster accumulation of chronic diseases in remote populations). This is broadly consistent with data from NSW, but as more data becomes available better estimates of severity will be possible.
Frequently Asked Questions:
Why are remote communities considered high risk?
The Indigenous cultures in Australia are the oldest culture in the world. Family, kinship, and community are important principles of Australian Indigenous cultures. As a result, households in remote Indigenous communities are often multigenerational, have many younger children (who are not eligible for vaccination), and interact closely with other households. These factors contribute to the spread of COVID-19 through the community and between age groups.
Additionally, cultural fragmentation, ongoing social inequities, and limited access to preventative and other medical care have significant impacts on remote communities. This leads to significantly larger rates of chronic illness in remote communities, increasing the risk of severe outcomes from COVID-19. Simultaneously, this reduces the availability of trusted sources of accurate medical information. This is further compounded by obvious challenges accessing more intensive treatment for COVID-19 from a remote community. Thus, residents in remote Indigenous communities are expected to be at higher risk of severe outcomes and less likely to be vaccinated than individuals of the same age in urban non-Indigenous communities.
Finally, because of the historical cultural fragmentation that has occurred in Indigenous populations, older members are important to maintaining culture. Thus, the spread of COVID-19 in remote communities poses a particular risk to the preservation of Australian Indigenous culture.
What interventions are studied in this work package?
There are many interventions available which are known to be effective against COVID-19. In this analysis, we consider varying levels of pre-emptive and reactive vaccination. We assume that there is a two-week lockdown once transmission is detected. We assume that people identified as cases are placed into effective isolation. We consider different strategies for contacts of cases: they may be quarantined in their household for 14 days (possibly transmitting to household members) or they may be quarantined separate from their community.
What is pre-emptive vaccination?
“Pre-emptive vaccination” means vaccinating individuals in the community before there is any transmission within the community.
Why is pre-emptive vaccination important?
This is the only way to guarantee that individuals are vaccinated before they are exposed. COVID-19 vaccines are very effective against severe illness and death, so getting vaccinated is the best way for someone to protect their own health. Additionally, the vaccines are effective against becoming infected, and even in breakthrough infections vaccination reduces the probability of transmitting to others. Thus, being vaccinated also helps protect family and community members against infection.
Is pre-emptive vaccination by itself enough to prevent epidemics in remote communities?
Because these communities have many (unvaccinated) young children and large households, even high vaccination coverage is unlikely to be enough to prevent epidemics in most remote communities.
If pre-emptive vaccination may not be enough to prevent an epidemic, is it still worth doing?
Yes. Pre-emptive vaccination will provide significant protection against severe disease for the individuals vaccinated. It will reduce the probability that any single introduction leads to sustained transmission, thus delaying the onset of community transmission. Additionally, if community transmission becomes established, pre-emptive vaccination will slow the outbreak’s spread, reduce the peak, and reduce the total number of infections.
What is “reactive vaccination”?
“Reactive vaccination” is the effort to increase vaccination within a community once transmission is ongoing. This has been widely used world-wide, and within Australia it has been used effectively in remote Indigenous communities and urban non-Indigenous communities in NSW.
Is reactive vaccination as effective as pre-emptive vaccination?
No. Once transmission has started in a population, it may not be possible to get vaccinated before being infected. Even if someone gets a vaccine, it takes over a month to be fully protected.
Why is reactive vaccination more effective in larger communities?
Reactive vaccination is most effective in those who are vaccinated well before transmission reaches them. In larger communities, it takes longer for the disease to reach everyone, and so a larger proportion of the population can be protected by reactive vaccination.
What can make reactive vaccination more effective?
Anything that slows the spread of infection through a community will increase the effectiveness of reactive vaccination by allowing more time for people to become protected. One effective way to do this is through pre-emptive vaccination as this slows the spread and reduces the number of people that need the reactive vaccination. Additionally, nonpharmaceutical interventions such as social distancing, quarantine/isolation, or stay at home orders create time for reactive vaccination to have more effect.
Would pre-emptive vaccination of younger children help?
We do not know for sure. If the vaccine reduces transmission among younger children, then we would expect vaccination of these children to improve overall outcomes in remote communities. However, the safety and effectiveness of vaccines in younger children need to be fully evaluated before COVID-19 vaccines can be approved for children aged less than 12 years in Australia.
What is the impact of quarantining contacts of cases away from the community?
Quarantining contacts of cases outside the community reduces the amount of transmission within the community compared to quarantining within the household. This slows the spread of infection (allowing more time for reactive vaccination), reduces the peak, and reduces the total number of infections. However, because of the importance of Country and family to Indigenous Australians, this measure imposes a significant cost on the individuals and community.
How severe are infection outcomes in these communities?
Despite the fact that we anticipate infections will generally be more severe, we are fortunate that there have not been enough infections in remote communities to get reliable estimates of severity by age. We have assumed that individuals under the age of 20 experience the same severity as observed in the general Australian population. Those 20 and over are assumed to experience outcomes corresponding to someone 10 years older in the general Australian population. Available data from NSW shows that this assumption is reasonable.