Vaccines are no longer controlling the spread of COVID-19 as fewer Australians roll up their sleeves for booster shots and variants that are better at evading immunity take hold.
With every vaccination campaign, take-up rates among eligible Australians have fallen – from 96.2 per cent for two doses to 72.4 per cent for three to 45.2 per cent for a fourth.
Vials of Pfizer’s updated COVID-19 vaccine during production in Kalamazoo, Michigan.Credit:AP
Federal government modelling suggests the transmission-suppressing effect of vaccination and prior infection has fallen from 60 per cent in Victoria in March 2022 to just 12 per cent now. NSW has seen a similar fall.
That modelling uses Omicron-based data: the variants circulating now are even more immune evasive, meaning the true number is likely to be even lower.
“One thing I think we can clearly say now is: current vaccination policies don’t have an effect on community-wide transmission,” says Associate Professor James Trauer, head of Monash University’s epidemiological modelling unit.
“We’re using vaccination as a way to protect those at high risk – particularly the elderly – against severe outcomes resulting from COVID infection, rather than from COVID infection itself.”
John Connell, a 41-year-old school facilities manager, received his third and fourth boosters when they were offered, but won’t be getting a fifth.
“I initially bought into the doing the right thing and protecting the vulnerable,” he says. “I have had COVID twice and shaken it off without any long-term symptoms – and am no longer afraid.”
Reaching 96 per cent double-vaccination came as a surprise to many vaccine scientists, especially after AstraZeneca’s safety scare in 2021.
But take-up of every successive dose has fallen. Current government health advice is for healthy people aged 18 to 64 to “consider” a fifth booster dose and notes the sole goal of Australia’s vaccine strategy is preventing severe illness, not transmission.
Professor Julie Leask, a leading vaccination researcher at the University of Sydney, expects our vaccination numbers will continue to fall unless something exceptional happens, such as the emergence of a dangerous new variant.
The emergence of Omicron and its offshoots also changes the vaccine calculus as these viruses are far more able to evade immunity – even from the new bivalent vaccines, which target both the original strain and the Omicron variant in a single shot.
Evidence suggests booster vaccination does cut your chances of passing the virus on, but the benefits are small.
A study of inmates in California’s prisons in early 2022 found unvaccinated prisoners had a 36 per cent chance of passing on the virus, compared with 28 per cent for vaccinated prisoners. Boosting provided a further small benefit.
Young, healthy and double-vaccinated people face a very low risk from the virus, even without a booster. For people who have had a booster, almost all the risk of death falls on people aged over 80.
“I think the jury is out on whether in the long term it would be cost-effective to be regularly boosting a lot of young, healthy people every six months,” says Professor Miles Davenport, head of the infection analytics program at the Kirby Institute.
With infections now flowing unchecked through the community, our focus must be on ensuring the vulnerable are getting their boosters, Leask says – especially those who haven’t been reinfected in the past six months.
“That is the group most at risk of severe disease and death from COVID-19. That is the group who need a booster – but it is difficult to identify them at a population level.”
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