People who have had a COVID-19 booster shot are far less likely to die or be hospitalised with the Omicron variant.
An Australian-first study on the effectiveness of coronavirus vaccines has found a third COVID-19 jab provides two-thirds more protection from death or hospitalisation from Omicron.
The study also confirmed the schedule of vaccines rolled out in Australia is protecting against hospitalisation and severe disease.
The National Centre for Immunisation Research and Surveillance (NCIRS) led the study that followed two million adults aged 40 and older living in Greater Sydney during the Omicron outbreak in January and February.
It tracked COVID-19 infections, hospitalisations and deaths.
It found having a booster provided 65 per cent better protection against hospitalisation and death from Omicron, compared with someone who had two doses.
People aged over 70 enjoyed significant benefits - the study finding for every 192 people over 70 who were boosted, at least one hospitalisation or death had been prevented.
The study also found reduced hospitalisation and death among boosted people aged 40 to 69.
Senior study author and director of NCIRS Kristine Macartney said the findings built on international evidence of vaccine effectiveness, but were unique as many Australians had not been infected with COVID-19 in late 2021.
"Yet we have shown strong protection against disease from Omicron following an mRNA vaccine as a third dose, irrespective of the vaccine brand given initially," Prof Macartney said.
"Future studies will look at protection gained following a fourth dose of COVID-19 vaccine, which is now recommended for those at highest risk of severe disease."
Lead author of the study Bette Liu said the findings demonstrate the best protection occurs when people follow vaccine recommendations.
In Australia about 70 per cent of the eligible population has received a third COVID-19 vaccine dose.
"I urge those 30 per cent who are yet to receive a third dose to do so as soon as possible," Associate Professor Liu said.
More than 31,000 new cases and 75 deaths were recorded in Australia in the latest 24-hour reporting period.
More than 3200 people are in hospital with COVID-19, with 122 of those in intensive care.
LATEST 24-HOUR COVID-19 DATA:
NSW: 8623 cases, 40 deaths, 1540 in hospital, 49 in ICU
Victoria: 7758 cases, 11 deaths, 468 in hospital, 35 in ICU
Tasmania: 1228 cases, no deaths, 45 in hospital, four in ICU
Queensland: 5268 cases, 19 deaths, 593 in hospital, 14 in ICU
ACT: 1159 cases, no deaths, 121 in hospital, none in ICU
South Australia: 2626 cases, no deaths, 246 in hospital, eight in ICU
WA: 4810 cases, four deaths, 246 in hospital, 11 in ICU
NT: 302 cases, one death, 17 in hospital, one in ICU.
