Tests are underway to determine if the Omicron variant of COVID-19 has been detected in South Australia.

Premier Steven Marshall said there were concerns related to a “couple of cases overnight”.

“We don’t have any confirmation so we’re taking it very cautiously,” Mr Marshall told radio FIVEaa on Friday.

“It hasn’t moved as quickly as we were thinking it might but we still have very little information on Omicron.

“Sometimes when you get a new case it takes some time to get that assessment, I think they call the genome sequencing, so we can know exactly what strain it is.

“We did get a couple of cases overnight and we are testing those to see if they could be our first cases of Omicron.”

It remains unclear if the possible spread of the strain to SA could disrupt the state’s plans to lift more local virus restrictions later this month or early in January based on the vaccination rate hitting 90 per cent.

On Thursday, Mr Marshall said the state government just needed a “few more days” before it made the call based on the number of people lining up for their second jab.

“We just need a few more days to see what that run rate is going to be in South Australia,” he said.

“The race is on at the moment to get to 90 per cent of all those 12 and over and I’m hopeful that we can do that by the end of the year.”

The most recent SA Health forecast suggests the double-dose target will be reached between December 23 and January 3.

Among the measures that could be revised are density limits at various venues, restrictions on dancing in nightclubs, and the 150-person cap on private functions.

As of Thursday, SA had 51 active COVID-19 infections with seven new cases reported.

Two were linked to the so-called Norwood cluster, taking it to 30.

The five others included four people who acquired the infection interstate before arriving in SA and one was a returned overseas traveller.

All SA’s cases are being managed in hotel quarantine apart from a woman in her 50s and a man in his 60s. They are in the Royal Adelaide Hospital in a stable condition.

-AAP