Despite a testing blitz in South Australia, zero new cases of coronavirus have been identified in the state.

Chief public health officer Dr Nicola Spurrier has also revealed the ‘unusual’ reason a patient tested positive to coronavirus despite having completed two weeks’ quarantine.

The returned overseas traveller tested positive on Wednesday.

Spurrier says during their self-isolation period, the person did not think to get tested as they experienced only loss of smell and loss of taste as a symptom.

The World Health Organisation has identified the “unusual” symptoms as a known identifier of COVID-19.

“For up to 3 per cent of people that was the only symptom they had of COVID-19,” Spurrier said.

SA Chief Public Health Officer Nicola Spurrier say a contact tracking app will be very helpful. Credit: AAP

Thirty-eight close contacts of the patient have been placed into quarantine.

Health authorities have also revealed that the number of cases linked to community transmission has increased from four to seven.

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However, Spurrier says the increase is not considered cause for concern.

“I just wanted to reassure the public that I’m no more concerned today than I was yesterday,” Spurrier said.