A guard at Spring Hill Prison in north Waikato has tested positive for Covid-19.

Corrections' regional commissioner for the central region Terry Buffery sent an email to all staff shortly after midday today advising them of the positive case.

'Last night we were advised that a staff member at Spring Hill Corrections Facility tested positive for COVID-19,” he wrote. 'The staff member is fully vaccinated, and has not displayed any symptoms. It is important to note that no other site is impacted at the moment.

'The staff member worked at the prison during the day on Saturday, and that evening was advised that he had a link to a location of interest. He was tested on Sunday and has been isolating since.”

It is understood the prison worker lives in Auckland.

'As soon as we were advised of the staff member's positive test on Monday night we identified and contacted 23 staff who had close contact with the staff member while he was at work,” Buffery wrote.

'All have been advised to isolate and get tested in line with Ministry of Health advice. These staff will not come back to work until they have returned negative tests and been cleared by the Ministry of Health.”

Prime Minister Jacinda Ardern and Director-General of Health Dr Ashley Bloomfield confirmed the case at a press briefing at 1pm on Tuesday.

'I have not got the details. He was asymptomatic,” says Ardern.

There had been 'rigorous record keeping” at the unit, which was inhabited by 123 people, she says.

”Residential environs are high-risk environments. Ultimately the people in that workplace are individuals that have had contact.”

In his message to staff, Buffery said urgent measures were being taken.

'All of the men in the unit where the staff member worked have also been segregated for medical oversight in line with section 60 of the Corrections Act, and they will also be tested by our health staff.

Anyone who has been recently transferred out of the unit will also be managed like this. Two men that have been released are being contacted and advised to isolate and get tested.

'The unit will now be operating as a quarantine unit. This means that all staff working in the unit will be wearing enhanced PPE, including masks, gloves, a gown and goggles when interacting with prisoners. The unit guardroom and shared spaces have been deep cleaned this morning, and this will be ongoing.

'We are in regular contact with Regional Public Health and are following all of their advice.”

Buffery went on to say they were 'well-prepared” and have 'put in place extensive plans to manage any risk to our staff or the men”.

'This includes the precautions we have been taking at alert level 4 to screen everyone coming into prison (including with the use of thermal cameras), shielding vulnerable prisoners, the use of PPE to protect everyone and the implementation of proximity detection cards to assist us with contact tracing.”

A staff member at Corrections' media department confirmed the legitimacy of the email.

Mike Mather/Stuff