COVID-19 vaccinations may have prevented almost 18,000 deaths among older Australians in NSW during the early Omicron era, new research has suggested.
A computer simulation carried out by researchers found the death rate “in the absence of a vaccination campaign” would have been approximately six times the actual total.
The research team, based out of universities in Melbourne and Tel Aviv, said in their report the campaign prevented 17,760 deaths among over-50s between August 2021 and July 2022.
“The Australian vaccination campaign was successful in reducing mortality over 2022,” the report said.
The team attributed the success to “high levels of engagement” by Australians with the vaccination campaign and the achievement of high levels of vaccination just before the 2022 Omicron outbreak.
Their research used modelling of state and federal health department data to show the effect on over-50s in NSW in three scenarios:
- How many deaths could have been averted if complete vaccination had been achieved by July 28, 2021;
- How many deaths were averted by the booster vaccine rollout; and
- How many deaths would have occurred in the absence of vaccination
“Australia was relatively late in mass vaccinating its population … beginning its program on 22 February 2021,” the report said.
“Four months later, less than five per cent of the population were fully vaccinated with two doses, making it the second-lowest vaccination coverage of any OECD nation at the time.
“Yet a few months later at the end of 2021, Australia had achieved one of the highest vaccination rates in the world, with more than 85 per cent of its eligible population fully vaccinated with at least two doses.
“Due to the rapid pace of the Australian roll-out [and] the very high public engagement with the program, vaccination coverage was at high levels when Omicron arrived.”
The report predicted 440 deaths would have been prevented with earlier vaccination, while 1,860 deaths were prevented by the booster campaign.
In mid-2022, cross-checking of death certificates in NSW revealed the state’s COVID-19 death toll was 2,433 as of April of the same year.
“In the [no vaccination campaign] scenario the entire population remains unvaccinated,” the report said.
“In the complete absence of vaccination, the model predicts an almost immediate major outbreak of Delta, followed by an even more extreme outbreak in the Omicron period in January 2022.
“The predicted but hypothetical Delta outbreak would have reached a maximum of 15,000 cases and maximum of 500 deaths per week in the NSW 50+ population.
“The real Delta outbreak on the other hand had approximately 75 deaths per week.”
Data at the time showed 82 per cent of deaths, around 270 people, occurred after January 2022 — when the Omicron wave was reaching its peak.
University of Melbourne epidemiologist Professor Tony Blakely said the rapid rush of vaccination before the Omicron variant began to spread was “good luck” for Australians.
“Australia was further lucky that when we opened up, Omicron was the circulating virus that was less lethal than [for example] Delta,” he said.
“But this paper makes the important point that even Omicron, in an unvaccinated population, would have had a massive death toll.
“The estimated deaths averted in this paper are probably underestimates, as higher vaccination rates would have had positive spill over effects of reducing transmission.
“In future pandemics, we hope that vaccines will be good at both stopping you dying and stopping you transmitting the virus – as this would reduce the health loss even more.”
Deakin University’s Associate Professor in Epidemiology Hassan Vally said the study formed part of an “important” assessment of the roll-out.
“Whilst it can’t be ignored that there were missteps, and there are things that could have been done better, it was a significant achievement that in Australia we were able to achieve one of the highest vaccination coverages globally,” he said.
“Importantly, the study authors have been fully transparent about the various limitations of this study and highlight that further work needs to be done when better data becomes available.”
The team noted their results “may be under-estimated and conservative” because actual death rates among unvaccinated Australians could have been impacted by herd immunity.
It also said the effects could have been affected by “potentially confounding factors [such] as age and comorbidity” in the over-50s age group.
Professor Paul Griffin, director of Infectious Diseases at Mater Health Services and a professor of medicine at the University of Queensland, said it was important to consider these limitations.
“While a really useful study in my opinion to show just how much benefit was likely obtained from the vaccination rollout in this country … [it] used data from one state only, NSW,” he said.
“It would be great to see a similar study from across the country as the experience with COVID-19 was not the same in all states.
“However there is not a single source of data that makes a larger study easy to do and NSW is the largest state.
“Modelling studies do not necessarily predict perfectly what would have actually happened.
“There are additional confounders that are difficult to take into account and the outcome from modelling is only as strong as the data that is put into the model, however in this case the data and methods seem robust.”
The study has been published in peer-reviewed scientific journal PLOS ONE this week.
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