Ten children are among the 71 people in South Australian hospitals being treated for COVID-19, as the state starts the New Year with 2100 new infections.

The state had 40 patients in hospital the day before.

Among those in hospital are 10 children, one teenager, eight people in their 20s, seven people in their 30s, five people in their 40s, 16 people in their 50s, nine people in their 60s, six people in their 70s, seven people in their 80s, and two people in their 90s.

Earlier in the week a child under two years of age died with the virus.

Four people are in intensive care, all adults, including one who is on a ventilator.

The virus is also appearing in vulnerable communities and prisons.

Rehab clinic rocked

Premier Steven Marshall said a worker at the Port Augusta sobering-up clinic was found to have the virus after increased detections in waste water.

Three residents at the clinic have also tested positive.

“All of those people will be designated as close contacts. We believe there could be between 30 and 50,” Mr Marshall told reporters on Saturday.

“We’re rushing to try to get that very vulnerable community into the appropriate setting so that we can continue to care for them.”

Prison outbreaks

Thirty-six inmates at three prisons – Mobilong, Adelaide Women’s and Adelaide Pre-Release – have the virus.

“We are putting plans in place to make sure we can manage this in the best-practice way,” Mr Marshall said.

The state processed 23,790 tests on Friday, while sampling has shown the majority of cases in the state are the Omicron variant.

Of the latest cases, 206 are children, 125 are teenagers, 916 are women aged between 18 and 97 and 856 are men aged between 18 and 97.

The demographics of five cases is unknown.

-AAP