There have been calls for more testing clinics after swathes of people attended the venues on Wednesday morning.
Motorists were reporting up to eight-hour wait times at the Victoria Park testing station.
The long lines have prompted calls for more 24-hour testing clinics.
South Australia has recorded one new locally acquired Covid-19 this morning.
Premier Steven Marshall announced the additional case just after 7am, which takes Adelaide’s cluster to a total of six cases.
The state has been plunged into lockdown due to rising case numbers.
It has now been confirmed the new cases are the higly contagious Delta variant.
The outbreak was sparked by an 81-year-old man who completed hotel quarantine in Sydney after returning from Argentina with his daughter and flew to Adelaide on July 8.
Victoria’s Covid cases are heading in the right direction, according to a leading doctor.
Dr Tony Baretone said it was impressive that the virus appeared to be under control.
“Even though we have extended the lockdown here for another seven days, the numbers are trending in the right direction with the exception of that one mystery case,” he told Today.
“They are all linked back to the two source cases so that is a positive. But yes, we are in the middle of winter and that’s the peak time for transmission of viruses in this kind of situation so we have just got to be a bit more clever and a bit more circumspect and be ready to do all the right things.”
A former Australian Medical Association president is concerned that the Covid-19 Delta is just as dangerous to young people.
Previous Alpha and Beta strains of the virus were found to be much more dangerous in older people.
Dr Stephen Parnis said it was a strange experience seeing that a teenager was in ICU with the virus.
“We know that the biggest, single risk factor for getting very sick with COVID is age but that doesn’t spare you if you are younger. You could be one of the smaller numbers who can get seriously ill,” he told Today.
He added, it could be more dangerous in young people as they are widely unvaccinated.
“One is that the new variant might be more aggressive, the concern is that those unvaccinated people are the ones most at risk and most likely to get sick.”