Middlemore Hospital chief medical officer Andrew Connolly said that was because there were a high number of absences for Covid-related reasons.
"We called on some doctors [house surgeons] who worked on our wards assisting our nursing workforce with a range of patient care," he said.
Resident Doctor's Association secretary Deborah Powell said the doctors had also been helping in the emergency department.
There were many nursing tasks that doctors could not do, but they were helping where their skills crossed over, doing jobs like stitching wounds, she said.
That was on top of their normal duties and shifts, she said.
Some medical technicians, like cardiac physiologists, had also been helping in the ED, she said.
Emergency departments throughout the city had been very busy with Covid-19 cases in the past week, with Middlemore bringing in senior doctors normally based elsewhere to help streamline its service.
There were a total of 520 people with the coronavirus across the city's three main hospitals yesterday.
All three hospitals had dramatically cut planned, or elective, surgery to free up staff to help elsewhere and to make sure there were enough beds available.
Many of those working in health in the city said the next seven to 10 days were a critical point in the outbreak and would be tough going in the health sector. Doctors were reassuring those who needed hospital-level care that they would get it.
There were 696 people in hospital nationwide, with experts suggesting Auckland's outbreak was likely peaking earlier than the rest of the country.