South Australia will most likely end its seven-day lockdown on time at 0001 on Wednesday after it recorded one new case linked to the Modbury cluster.

South Australia is likely to end its week-long COVID-19 lockdown on time after reporting one new virus infection linked to the Modbury cluster.

Premier Steven Marshall says the shutdown will end at one minute past midnight on Wednesday morning, provided there are no further "unlinked" coronavirus cases.

"Working together we've been able to demonstrate we can get through this very difficult situation," he told reporters on Monday.

"We're absolutely delighted with how the people of South Australia have worked with the restrictions. Everyone has made extraordinary sacrifices this week.

"We said we wanted to go hard, we wanted to go early and we wanted to knock this off."

When the lockdown lifts, SA will keep a range of heightened restrictions including a general density requirement of one person to every four square metres.

Masks will be required in high-risk settings, such as aged care centres, in medical services and on public transport.

The wider use of masks is strongly encouraged.

All food and drink consumption must be while seated and dancing and singing remain banned.

Family gatherings will be limited to 10 people although weddings and funerals can have up to 50.

Schools will also reopen on Wednesday.

Mr Marshall said more details of the transition would be released in the coming days, including arrangements for the resumption of sports training and competition and revised rules for people returning from interstate.

The new restrictions will remain in place for at least a week.

On top of the continuing measures, the premier urged all people to strongly consider their need to move around, with working from home a preferred option.

Business SA Chief Executive Martin Haese said local companies had dug deep during the past week and once again showed their resilience.

"These restrictions will continue to hurt many businesses, but Business SA's position remains that any restrictions should not be in place for a moment longer than needed," he said.

"We will continue to advocate that position, alongside additional support measures for affected businesses to both the state and federal governments."

With one new locally acquired case, an 87-year-old man, the Modbury cluster now stands at 19 confirmed infections.

The man contracted the virus after visiting the Tenafeate Creek winery near One Tree Hill last week, which is now linked to 11 infections.

However, Chief Public Health Officer Nicola Spurrier said more cases could still crop up, most likely in close contacts of those already found to have the disease.

She said it was hoped any new cases would already be in quarantine.

"We've thrown 150 per cent effort at this. We have got our teams working around the clock, throwing the net as wide as possible," she said.

"But it is a very tricky virus and this is why when we come out of lockdown we all have to remain very observant, very cautious."

Prof Spurrier said of the 19 confirmed infections in the latest cluster, six people had received one dose of the vaccine and 12 had not been vaccinated.

The remaining person's status was unknown.

The Modbury cluster began with an 81-year-old man who recently arrived in Australia from Argentina and was quarantined in Sydney before travelling to Adelaide, where he tested positive.

Genomic testing has confirmed the man became infected while in Sydney, not while he was in Argentina.