It comes ahead of a national cabinet meeting on Wednesday where state leaders will discuss peeling back some restrictions, including reducing isolation periods from seven days to five.

Targeted messaging will feature on TV, print, radio, online, social media and outdoor displays in South Australia over the next month, warning a fourth jab is advised because COVID immunity fades.

“We want more South Australians to get their fourth dose, stay out of hospital and reduce pressure on frontline workers,” said Health Minister Chris Picton.

“While COVID admissions are decreasing, our hospitals remain very busy and the pandemic continues to have an impact.”

A new eligibility checker has also just come online to clear any confusion people may have over their fourth dose.

It is available to anyone over 30 who received a third dose at least three months ago or last had COVID three months ago.

Only 41 percent of people surveyed in the lead-up to the campaign correctly identified when they were eligible for their fourth dose.

South Australia has the highest fourth COVID vaccination uptake of any mainland state, with about 41 per cent of the state’s eligible population vaccinated.

Only Tasmania and the ACT have slightly higher rates of fourth dose vaccination per population, as per latest Commonwealth data.