The analysis by the South Australian Health and Medical Research Institute (SAHMRI) found unvaccinated people are also eight times more likely to be hospitalised than those with up-to-date vaccinations.

Researchers studied 70,450 South Australian COVID-19 cases between August 1, 2022 and October 31, 2022, finding those who are partially vaccinated against COVID-19 with just one or two doses were about three times more likely to be hospitalised and two times more likely to die than those who are fully-vaccinated.

Older age was found to be an independent risk factor for death and hospitalisation from COVID-19, with each vaccine dose gradually lowering the chance of death or hospitalisation.

“This research from SAHMRI is based on South Australia’s real-world data and shows just how important vaccination is in protecting against serious illness,” Health Minister Chris Picton said.

“We know that the virus is here to stay and being up to date with vaccinations help to protect from the severe impacts of COVID.”

The release of the findings comes ahead of the national rollout of the fifth COVID-19 bivalent vaccine.

From today, Australians aged over 18 who have not had the virus or a booster dose in the past six months are eligible for the dose.

The fifth dose, which is available at GPs and pharmacists and includes protection against the original COVID-19 strain along with the Omicron variant, was previously restricted to adults who were immunocompromised.

Health authorities particularly recommend a fifth dose for those aged over 65, those with medical co-morbidities, or those with a disability or complex health needs.

Chief public health officer Professor Nicola Spurrier told ABC Radio Adelaide this morning that she was worried that people were becoming complacent with COVID-19 vaccinations.

“They might have had COVID in the past and they think, well it wasn’t that bad, but we know that virus evolves,” she said.

“That’s one of the good things about mRNA vaccines – you can change the variant quite quickly and so you can update your vaccine.

“Pfizer has done exactly that.”

SA Health on Friday reported 1720 new COVID-19 cases over last week – up from 1495 the week prior.

As of 11.59pm on Thursday February 16, there were 42 infectious people in hospital, including five in intensive care.

There were also seven COVID deaths reported over the past week.

The latest COVID-19 wave is expected to peak in March during the festival period, with a second COVID wave predicted for winter.