All staff, patients and visitors to Southern DHB facilities will need to wear a medical grade face mask from now on.
The DHB announced the requirement for everyone aged over eight as it prepared for Omicron to hit the south.
Medical officer of health Dr Susan Jack said medical masks were much more effective at protecting people from Covid-19 than fabric masks or cloth face coverings.
"This is something we can all do to help protect our vulnerable patients and our communities," she said.
"People should also continue to practice physical distancing which means staying at least one meter away from people you don't know."
The Southern DHB would make medical masks available for all patients, visitors and staff in both clinical and non-clinical settings.
Chief operating officer Hamish Brown said all patients were required to wear medical masks unless they had a mask exemption or were physically unable to for clinical reasons.
"Visitors are asked to wear a medical mask, scan into all areas they visit in the hospital using the QR codes, practice hand hygiene and stay home if they are sick."