Modelling reveals number of lives saved by COVID vaccine rollout

Unvaccinated Australians aged 50 and over had a mortality rate 12-fold higher than those who received three doses, according to computer simulations from Monash University and RMIT.
 
The new research, which assessed the impact of Australia’s vaccine rollout in NSW during the end of the Delta wave and arrival of Omicron, suggests 17,760 deaths were prevented over the 12-month period – a ‘conservative first approximation’ based on the available data.
 
Deakin University epidemiologist Associate Professor Hasan Vally was not involved in the research but said it has contributed to the ‘important task’ of evaluating all aspects of Australia’s pandemic response.
 
‘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.
 
‘This evaluation suggests that if there had been no vaccination rollout, approximately 21,250 deaths would have occurred in NSW, which is some six times higher than the total that was observed over the study period.
 
‘In addition, it was estimated that unvaccinated individuals had a 7.7-fold greater mortality rate than those who were fully vaccinated [two doses], with this mortality rate estimated to be 11.2 times higher when compared to vaccinated individuals who received a booster.’
 
To form their findings, the team used a simulation of vaccination and COVID-19 mortality rates in people aged 50 or older to see how it impacted deaths. NSW was selected as it had the highest quality data available and was seen to be broadly representative of the national experience.

The average weekly death rate during the study period was 19.8 per 100,000 people for the unvaccinated and 4.7, 2.6, and 1.8 per 100,000 for those who had received a single dose, two doses, or three or more doses, respectively.

Director of Infectious Diseases at Mater Health Services, Professor Paul Griffin, also commented on the research, describing the findings as ‘significant’.
 
‘The rapid development of safe and effective vaccines for COVID-19 is perhaps one of the greatest achievements of medical science,’ he said.
 
‘Given the COVID-19 vaccines, like most vaccines in fact, are not “perfect” in that they do have some limitations including not completely preventing infection in all recipients, and not unexpectedly they have been responsible for some adverse events, many have been critical of them.
 
‘Ultimately, while it should be clear that the vaccination rollout had a tremendous impact, this study adds useful estimates of the large numbers of lives saved and should help to reinforce the benefits of vaccinating for COVID-19.
 
‘While the benefits of vaccinating for COVID-19 now are likely to have changed somewhat, it will remain an important part of our strategy for managing COVID-19 for the foreseeable future.’
 
However, he also noted some study limitations.
 
‘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,’ Professor Griffin said.
 
‘[Also], 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.
 
‘Finally, while relatively recent and therefore including the early Omicron period, the SARS-CoV-2 virus has evolved since the study period and so the situation with COVID-19 has changed.’
 
More than 17.1 million COVID-19 vaccinations were administered in NSW during the study period (7 August 2021 to 9 July 2022), the majority of which were delivered by GPs.
 
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COVID-19 vaccination vaccine rollout