• John McDonnell

Setting the freedom figure won’t be easy


Determining the vaccination level that will end lockdowns and open up all the borders will not be easy. It may be that there is not a single number.


This is because different vaccines have different responses to different strains of the virus. In other words, a country that is 100 per cent vaccinated with AstraZeneca will have a different level of protection to one that is fully vaccinated with Pfizer. This gets more difficult when there is a mixed vaccination program, as there is in Australia.


Professor Tony Blakely, who is not working for the Australian government, has developed his own model to predict the level of vaccination that will enable Australia to get to a situation where borders can be opened and lockdowns avoided. To use prime minister Scott Morrison’s phrase, the point at which Australia moves from suppression of the virus to living with the virus.


Professor Blakely makes the point that vaccination alone will not be the answer to dealing with the risks entailed in opening the borders. He says in an article in ‘The Conversation’ on Monday:


“The key trick, though, is to not think of vaccination as the only intervention. It is vaccination — together with three other measures: ongoing aggressive contact tracing, mask-wearing in high-risk settings and some physical distancing — that will make it safe to open.
“Put another way, even when we immunise all Australians who want to be protected against COVID-19, we’re unlikely to achieve herd immunity through vaccination alone.”

Modelling done by the University of Sydney and the Burnett Institute indicates that at least two-thirds of the population will need to be vaccinated if we are to avoid a public health crisis when we open up.


This makes a nonsense of people who point to the UK opening up with only 50 per cent of people fully vaccinated and arguing Australia is being left behind.


The Australian economy is stronger than the British economy and our health outcomes are better.


Nevertheless, we want to see the return of foreign students as soon as possible and we desperately need to import skilled workers. This is why we need to identify a number that makes this possible.


Professor Blakely says:


“…given the Delta variant means an average infected person infects five others without any other measures in place, and given vaccines are not perfect, Australia would need 90 per cent of adults and children vaccinated to achieve herd immunity (through vaccination alone). This is unlikely.
“There will be some waning in vaccine immunity over time, and new variants for which Pfizer and AstraZeneca are less effective. However, even with 100 per cent of the population vaccinated, herd immunity may not be achieved by vaccination alone until booster vaccines become available.”

In the circumstances, including the fact that over 60’s are getting Astra Zeneca and 16-60-year-olds are getting Pfizer, the effectiveness of each of these vaccines on each cohort means that a vaccination rate of 90 per cent - together with other public health measures as required - will enable us to get to phase three of the national cabinet plan with all borders open.


However, it is unlikely that will get to phase four, ‘back to normal’, without the development of new vaccines against new variants.