Opening up at 80% vaccinations may come with a price

| September 1, 2021

Australia’s National Plan to relax COVID-19 restrictions puts too many lives at risk and could hamper thousands more Australians with ongoing illness, according to new modelling from researchers.

The researchers argue that at least 90 per cent of all Australians, including children, must be vaccinated against COVID-19 before fully relaxing public health measures and opening the international border.

Professor Quentin Grafton from The Australian National University, Dr Zoë Hyde from the University of Western Australia and Professor Tom Kompas from the University of Melbourne, examined the National Plan to reduce restrictions once enough adults are vaccinated.

Under the National Plan, once more than 80 per cent of adults receive two doses of COVID-19 vaccines, equivalent to approximately 65 per cent of the total population, the nation will “manage COVID-19 consistent with public health management of other infectious diseases”.

Professor Quentin Grafton said the new modelling showed “we simply can’t afford to do that, both in terms of lives and long-term illness from COVID”.

“We found substantial morbidity and mortality is likely to occur if the Australian Government sticks to the National Plan,” he said.

“Our modelling shows if 70 per cent of Australians over 16 years of age are fully vaccinated, with a 95 per cent vaccination level for those aged 60 years and over, there could eventually be some 6.9 million symptomatic COVID-19 cases, 154,000 hospitalisations, and 29,000 fatalities.

“And assuming 80 per cent vaccination coverage for only those over 16, as per the National Plan, there could be approximately 25,000 fatalities and some 270,000 cases of long COVID.

“In contrast, and if children are also fully vaccinated, national fatalities – for all age groups – would be reduced to 19,000 with 80 per cent adult vaccination coverage. This would fall to 10,000 at a 90 per cent adult vaccination coverage.

“Children also directly benefit from vaccination. If we could achieve 75 cent vaccination coverage among children and adolescents, we could prevent 12,000 hospitalisations in these age groups.”

The researchers argue four key steps must be taken before “exposing Australians to uncontrolled COVID-19”.

These include vaccinating both children and adolescents; reaching 95 per cent full vaccination among people 60 and older as well as other vulnerable groups, including Aboriginal and Torres Strait Islanders; giving an mRNA booster shot to all Australians vaccinated with AstraZeneca, as well as a booster shot to those vaccinated with an mRNA vaccine, when appropriate; and reaching more than 90 per cent vaccination coverage among all Australians.

“The consequences of prematurely and fully relaxing public health measures to suppress COVID-19, even after vaccinating 80 per cent of adults, would likely be irreversible, and unacceptable to many Australians,” Dr Hyde said.

“Even if the country achieves the four steps we are calling for, fully relaxing public health measures to eliminate community transmission could still, eventually, result in some 5,000 fatalities and 40,000 cases of long COVID.

“For all these reasons and more, it’s simply too dangerous to treat COVID-19 like the flu.

“We also can’t forget about our children, who can get very sick from this virus and need protection before we open up.”

Professor Kompas said the Australian Government still has an opportunity to devise “a safe and affordable transition to a ‘post-COVID-19’ era”.

“Our projections of hospitalisations and fatalities would have been even worse if we had used the higher preliminary estimates of the increased virulence of the Delta variant,” he said.

“This means our projections likely represent a lower estimate of the cumulative public health outcomes of fully relaxing public health measures at Phase D of the National Plan, or sooner, if outbreaks are not effectively suppressed or eliminated.

“If National Cabinet revises its strategy to include our four vaccination steps, many lives will be saved, and many more, including children, will not suffer from debilitating long COVID.”

The modelling from Professor Grafton, Dr Hyde and Professor Kompas is available online as a pre-print publication. Read an analysis article by the three researchers about their findings and proposed four-step national COVID-19 response at Policy Forum here.

Model results depend on inputs and assumptions

Nikolai Petrovsky, a Professor in the College of Medicine and Public Health at Flinders University and Research Director at Vaxine Pty Ltd notes that 

“We need to be extremely cautious about making policy decisions based on just a single model. Such models are extremely sensitive to their inputs and assumptions, and can easily provide misleading results. We need to remember that last year many of the early pandemic models incorrectly predicted that COVID-19 if left unchecked would reach an early peak within just a few months and would then spontaneously disappear due to herd immunity.

“Many governments including UK, Sweden, Brazil made major decisions based on those modelling results with disastrous consequences, collectively resulting in over a million avoidable deaths across those countries who did not implement any early control measures based on misplaced trust in those models. We don’t want to see a repeat of this in Australia.

The Doherty model is based on assumptions that the two current vaccines provide high levels of sustained protection against delta virus transmission, assumptions poorly supported by available data. At best, at their peak these vaccines might provide 50% protection against transmission but this then appears to rapidly wane even while protection against serious disease is relatively maintained.

“Factor this real world data on the delta virus and efficacy of these vaccines into the model and a population vaccination coverage of at least 90-95% is more likely to be needed to reduce the likelihood of future uncontrolled outbreaks if other control measures are relaxed too early.

Another ongoing issue is the repercussions of long Covid, and whether the current vaccines will reduce this risk. One of the surprising features of long Covid is that it does not appear to correlate with severity of disease, with many sufferers being young patients who have only had mild infections.

“If current vaccines only reduce disease severity and do not prevent infection then they may not reduce the incidence of long Covid – more epidemiological data is urgently needed on this question.

The argument that some lives will need to be sacrificed in the interests of avoiding future lockdowns presupposes that a final solution is in sight, such that these lives will not be lost in vain. However scientific evidence suggests that while current vaccines are beneficial they do not by themselves represent a final solution, and better alternatives are still needed.

What is needed is acceptance that the pandemic still has a way to go, the ultimate solution is still not available and hence we should continue to apply policies that prevent/stall unnecessary deaths, while investing all available resources into more quickly finding the ultimate solution, at least one aspect of which might be safer and more effective vaccines that provide better protection against the variants and have more impact on reducing transmission than current candidates.”