Testing at the Bolivar wastewater treatment plant has for past few weeks detected a higher count of COVID-19 in sewerage than what is being picked up in the community through PCR and rapid antigen testing.

Chief public health officer Professor Nicola Spurrier first raised concerns about wastewater testing last week, saying the data showed there were COVID cases that were going undetected in the community.

At the time, she said the disparity could be caused by a drop in the number of people reporting positive rapid antigen tests or seeking PCR tests.

Asked this morning how many more cases were going undetected, Health Minister Chris Picton said the results showed there “thousands more cases in the community every day”.

He said authorities believed there was an “under-ascertainment in the community”, but they were unable to determine where in Adelaide cases were more likely to go undetected, as the Bolivar treatment plant services most of the city.

“Over the past week or so and on our latest modelling (we) put that into the figures,” he said.

“That’s not just a statistical issue, but that’s a real-life issue that people aren’t getting tested.

“That might mean that we aren’t getting people those antivirals and treatment as quickly as possible – that’s the main concern.”

South Australia today reported 4197 new COVID cases – up from 3773 yesterday.

There are 365 people with COVID in hospital, including eight in intensive care.

Four people – two women in their 80s and two men in their 90s – have died after testing COVID-positive.

The government today released data showing South Australian doctors have prescribed more antivirals to treat COVID-19 symptoms than the national average, with 2458 scripts issued in the week ending July 17, compared to 491 two weeks earlier.

The federal government last month relaxed the eligibility requirements to allow all COVID-positive patients aged over 70, as well as those over 50 with multiple chronic health conditions, to access the medication.

Picton said the state government would “continue discussions” with the federal government to further relax the eligibility criteria to allow younger people to access antivirals.

“We really were really appreciative of the change in the eligibility from what was a very restrictive, very complicated, difficult to understand formula, to what’s quite a clear and simple formula that targets the highest-risk people,” he said.

“I know that there’s particular people under the age of 50, who have particular conditions, who are concerned as to whether they may be eligible or not.

“There is some pathway where they could be eligible – it’s a much stricter pathway – and we’re going to be continuing discussions the Commonwealth about that.”

Picton this morning visited the government’s new GP Respiratory Centre at Kilkenny, which opened last Friday to treat people with mild to moderate respiratory symptoms, including those who have tested COVID-positive.

Patients do not need a referral to visit the centre, but they do need to book online or over the phone.

The centre is one of five which have opened across Adelaide in recent weeks to alleviate pressure on Adelaide’s over-stretched emergency departments.

The SA Health hospital dashboard showed there were no inpatient beds available across Adelaide hospitals this morning.

The metropolitan hospital system can fit 2959 patients, but at 11am, the dashboard showed there were 2923 inpatients admitted and 112 patients who were stuck in emergency departments waiting for a bed.

A “code white” was in place for the Lyell McEwin emergency department, meaning no treatment beds were available.