By Tony Blakely
There has been a bit of hullabaloo and simplistic talk of late. An overstatement of what vaccines alone can achieve. A misplaced notion that we just need to achieve a particular level of vaccine coverage, and everything will be tickety-boo.
That is – unfortunately – rubbish. To achieve herd immunity through vaccination alone will require at least 80 per cent of the population immune, which (given vaccines are not perfect) will require at least 90 per cent vaccine coverage – including children. That won’t happen anytime soon in Australia.
Prime Minister Scott Morrison announcing his government’s plan on Friday to transition Australia’s response to the coronavirus pandemic.Credit: Alex Ellinghausen
Vaccination is necessary, but alone is not sufficient, to get us to the other end of this pandemic. It is just one tool – albeit it the most important one – in our toolbox. We will still need to complement whatever vaccination coverage we achieve with excellent contact tracing (which will work so much better augmented by higher vaccination rates), mask wearing in high-risk environments, and physical distancing where practicable.
To some extent we will ‘top up’ vaccine induced immunity with a bit of infection-induced immunity – which means we will have to accept some level of mortality from COVID-19. We need to think about the number of deaths we will accept in the year after we open up, and set out border and internal infection control policies to match whatever vaccine coverage we have achieved, to keep within our risk tolerance.
Together, vaccination and these other measures can keep the effective reproductive rate of the virus low enough most of the time in most places to prevent serious outbreaks. And we can change the mix of measures over time as vaccine coverage increases.
So, given all of that, what do I make of the national plan announced by the federal government on Friday to transition Australia’s response to COVID-19? It is actually pretty good.
In setting a target of 70 per cent to move into Phase B (transition phase), then 80 per cent coverage to move into Phase C (consolidation), it both provides targets we can aspire to with collective carrots when we get there, and clearly explains the role of non-vaccine measures during these transitions.
The plan also lays down a framework for more rewards to those who are fully vaccinated. For example, first access to free travel from and returning to Australia. There will be other carrots that a working group from Victoria, the Northern Territory and Tasmania will determine.
I liked and agreed with the Prime Minister’s cautious pointing to the diminishing need for lockdowns as we get vaccination coverage up, while acknowledging that even above 80 per cent vaccine coverage there may still be an occasional need for lockdowns in targeted areas to protect vulnerable people. A good balance of road-mapping, yet caution, given this damn virus will probably throw us more curve balls.
I think we may even exceed the expectations set out in the plan. For example, the risk of an infection coming into Australia with arrivals from China is infinitesimally low – as infection rates in China are so low, and kept low with strong measures. Allowing – say – a large cap or even uncapped arrival of Chinese international students is possible before 2022.
Finally, what if we do not get to 80 per cent or even 70 per cent vaccine uptake by adults by the end of the year, as the Prime Minister hopes? I endorse these targets, and I hope and believe we should achieve them this year. And in Phase C or D include children in the vaccine rollout.
If we do not make these targets by then, the good news is we could still progress to the next phase – we just need to carry through some additional measures, such as restrictions on gatherings.
Indeed, at the University of Melbourne we have modelled just these things, showing how to open up and still achieve an ‘acceptable’ level of mortality and morbidity. We could do so at a lower level of vaccine coverage by – say – not opening borders to higher risk countries. Therefore, I suspect – and even recommend – that the adult vaccination targets will evolve, to something like “70 per cent or mid-November – whichever comes first”, and “80 per cent or Christmas”.
We have not yet seen the modelling from the Doherty and Treasury that underpinned this national plan, but we can say the output of all this modelling and planning looks good.
Professor Tony Blakely is an epidemiologist at the University of Melbourne.
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