Just two per cent of coronavirus patients admitted to intensive care since Australia's vaccine rollout started were fully vaccinated.
New figures underscoring the power of immunisation have revealed a whopping 86 per cent of people needing intensive care treatment had not received a single dose.
Monash University's SPRINT-SARI project examined 574 ICU admissions since February 22, when the first coronavirus vaccines started to be rolled out across the nation.
Only two per cent (13 people) had received two vaccine doses, while the equivalent of 12 per cent (69 people) had a single shot.
The remaining 492 patients were unvaccinated.
Infectious diseases epidemiology professor Allen Cheng said younger people were featuring more prominently in intensive care admissions in recent weeks, including pregnant women.
"The shift in age of those admitted to ICUs is anticipated, given older Australians were prioritised during the early phases of rollout," he said on Wednesday.
"These figures again underscore just how much protection vaccinations offer in terms of your likelihood of getting seriously unwell with COVID-19."
SPRINT-SARI is a hospital-based surveillance database that tracks the sickest coronavirus patients in Australian hospitals and intensive care units.
Intensive care director at Melbourne's Austin Hospital Stephen Warrillow said staff were more fatigued now than during last year's Victorian second wave.
"There is a growing number. We have had additional admissions overnight," he told the Nine Network.
Dr Warrillow said getting the community as close to 100 per cent vaccinated was crucial.
National vaccine rollout co-ordinator John Frewen said projections showed Australia could hit 70 per cent double-dose coverage for people aged 16 and over in October.
"It is possible to get to 80 per cent this year but the variable here is people and people's preparedness to get vaccinated," he told ABC radio.
Lieutenant General Frewen said international experience showed getting from 70 to 80 per cent was difficult.
But he is encouraged by public sentiment surveys showing more than 80 per cent intend to receive a jab, another group are unsure, and only a small percentage are anti-vaccination.
Australia is on the cusp of exceeding 70 per cent first-dose vaccination coverage for people aged 16 and above, while almost 44 per cent have received both jabs.
NSW reported 1259 new cases and 12 deaths on Wednesday as the state passed 80 per cent single-dose immunisation coverage.
Curfews in western Sydney's 12 local government areas of concern will be lifted immediately.
Victoria recorded two deaths and 423 new cases, with regional city Ballarat plunged into a one-week lockdown due to rising numbers.
Shepparton will exit lockdown from midnight on Wednesday.
There were 13 new infections in Canberra, where a lockdown extends until October 15.
The Northern Territory is aiming to have 80 per cent of its eligible population fully vaccinated against COVID-19 by early November, pledging a wide-ranging reopening plan.
"We are now in a 50-day race to freedom," Chief Minister Michael Gunner said.
Queensland plans a "super weekend for vaccinations", with all 80 state-run community vaccination hubs accepting walk-ins on Saturday and Sunday.
Australian Associated Press