South Australian health authorities have expressed concern about a second “strong” result for COVID-19 in the wastewater of Adelaide’s CBD.

SA Health said anyone who has had any coronavirus symptoms – no matter how mild – and has been in Adelaide’s CBD during the past week should get a COVID-19 test.

The northern part of Adelaide’s CBD has quarantine hotels with returned travellers, but has also been frequented by tens of thousands of people during the festival season.

Deputy chief public health officer Dr Emily Kirkpatrick said it was the strongest wastewater result for the coronavirus since the Parafield cluster that briefly sent South Australia into lockdown in 2020.

“We do have old cases within our medi-hotels within that catchment,” Dr Kirkpatrick said.

“That could certainly explain those results we’re seeing. However, we are still alarmed by this.

“We’re not saying there is any community transmission here in South Australia [but] it is really important you do get tested even if you have the slightest of symptoms.”

She said SA Health was looking at a range of possible explanations for the presence of coronavirus in the reading.

“Whilst we are alarmed at SA Health that we’ve seen this result, we want the community to remain alert and for them not to be alarmed about this result,” Dr Kirkpatrick said.

Tweet from @SAHealth

Late last week, SA Health said there had been a “very strong” positive result for COVID-19 in Adelaide wastewater.

The department said the catchment in which the reading was detected did not include the dedicated facility for confirmed COVID-19 cases, Tom’s Court Hotel, but could have been linked to old cases of coronavirus in other city medi-hotels.

The state had two new cases on Tuesday, both of whom are returned travellers from overseas who have been staying in a medi-hotel since they arrived.

One is a teenager and another is a man in his 60s.

Dr Kirkpatrick said 2655 COVID-19 tests were conducted in South Australia on Monday.

“We’re very pleased to see that people have responded to our calls to go and get tested in response to our recent positive wastewater results,” she said.

The news comes as COVID-19 vaccines are administered to frontline healthcare workers and other high-risk groups in South Australia.

Among them was Dr Dharminy Thurairatnam, the Lyell McEwen Hospital doctor who helped detect the earliest case of coronavirus in the Parafield cluster, who received her Pfizer vaccine jab on Tuesday.

She said she and other healthcare professionals were looking forward to getting the jab.

“We are very excited about it and we certainly want to get all ourselves immunised, vaccinated, because we can only achieve herd immunity when all of us choose the right thing to do which is to roll up your sleeves and have the vaccine,” Dr Thurairatnam said.