Since Tuesday, one in every 10 people presenting at the Middlemore Hospital emergency department has tested positive for Covid-19.
The Auckland hospital gives rapid antigen tests to everyone who turns up for treatment, even if they do not have symptoms of the coronavirus.
Middlemore Hospital head of emergency department Dr Vanessa Thornton told Morning Report that trend had continued over the week, and the hospital expected that.
"It is slowly increasing, but it will be increasing more dramatically over probably the coming weeks, one would think ... as predicted in many of the modelling processes that have occurred, and we have our own epidemiologist that looks on a day-to-day basis and we're expecting the cases to increase across the next few weeks."
The number of admissions in general was also expected to rise.
Some patients were coming in with virus symptoms and underlying comorbidities, while others presented with other conditions - broken arms or legs - and tested positive upon being admitted to hospital, Thornton said.
"We may have to reduce some other services in order to cope, but we have a plan in place to cope with this surge going up in the next four weeks" - Middlemore Hospital head of emergency department Dr Vanessa Thornton.
"We do have people presenting with cough fever and it exacerbates their underlying condition, if that makes sense, so it makes their underlying comorbidities more obvious, though they would be sicker than you and I would be with the virus.
"There are few people that are still presenting with … pneumonia, or infection and their lungs, but that's a much, much smaller proportion than happened in the Delta outbreak.
"They are people who are very, very very short of breath, but we had a lot of those people in intensive care in the last outbreak, which was a much different virus than Omicron."
The situation for staff was challenging, Thornton said.
"It's been challenging for the last two years over this whole period for the staff, from added processes, for example, the PPE you just discussed, and it is very warm in summer … the staff have responded really well to this and had been working very, very hard but it is challenging in this environment."
As for the wider hospital's capacity to deal with Omicron, Thornton said: "We have changed all our process to adapt, but it's challenging. We already had reduced staffing … prior to this and with the illness that's affecting the community, it obviously affects our workforce as well.
"The challenges in the workforce just add to the pressures from the patients, but Middlemore has been prepared for this.
"We may have to reduce some other services in order to cope, but we have a plan in place to cope with this surge going up in the next four weeks."