The South Australian government is launching a $2 million advertising campaign to encourage people to receive a third COVID-19 vaccine, as authorities report another five people with COVID have died.
About 72 per cent of eligible South Australians have had their third dose. Health Minister Chris Picton said the campaign was targeting the remaining group.
"That still means there are 28 per cent of those people who have had two doses who haven't come forward yet to have their third dose," he said.
Premier Peter Malinauskas said the state's hospital system remained "under a lot of pressure", and being fully vaccinated was one way of avoiding hospitalisation.
"You don't want to be the person who is only double-vaxxed, ends up getting COVID, and then finds themselves on a ventilator in our hospital system wishing they had had a third dose," he said.
Chief Public Health Officer Nicola Spurrier said the "science was absolutely crystal clear" that three doses of the vaccine were required, even in people who have previously had COVID-19.
"I'm very keen to go away from talking about boosters because it's not a booster; the course is actually three doses for Omicron," she said.
"It's a different variant … it's not Delta, and it's 100 per cent Omicron in our state so it really is three doses [that are needed]."
Professor Spurrier said the percentage of South Australians who were fully vaccinated had not budged for some time.
"Every day I look at it, hoping it's going to go up, but it has just stayed the same," she said.
The state recorded 2,788 new COVID infections today and five deaths of people with COVID, ranging in age from their 60s to their 90s.
Professor Spurrier said there were 214 people in hospital, including nine in intensive care.
"As we lift restrictions, we will expect to see more cases in our community, and what we are really focusing on is people being protected and not ending up in hospital because it is preventable," Professor Spurrier said.
The number of active cases in the state has continued to decline to 21,386.
Professor Spurrier also said flu vaccination rates were "not as good" as at the same time last year.
"Obviously we are concerned that people who have flu, or COVID, or have them both together, will get really sick and end up in the Royal Adelaide or one of our other hospitals," she said.
"And that's not good for them, and that's not good for our hospital system as well."
A 'shocking situation' in intensive care units
Mark Plummer, the head of research and innovation at the Royal Adelaide Hospital's intensive care unit, has joined the state's vaccination campaign.
He said he saw regret in under-vaccinated or unvaccinated patients "daily".
"What I would implore you to consider is your family," he said.
"What we are getting sick and tired of is having to speak with families at the bedside and dealing with the regret of not having been fully vaccinated.
"It's a shocking situation.
"The patients are on a ventilator. They can't speak for themselves. They're unconscious. So that grief is held by their family and that regret is held by their family if they haven't been fully vaccinated."
Dr Plummer said there was a "huge over-representation" of partially vaccinated or unvaccinated people in the intensive care unit.
"The solution is simple," he said.
Dr Plummer said complacency was evident in all age groups, including in high-risk patients.
"There's a lot of misinformation out there and unfortunately a small minority have a very loud voice on social media and can change the message from what is very clear; that this is a very serious disease and that vaccines work," he said.