Hospitals around the country have been flat out today, with all but a handful at close to maximum capacity.
This is despite trying to keep numbers down while nurses were on strike by cancelling routine and non-urgent appointments.
About 30,000 nurses, midwives and other health workers walked off the job at 11am this morning.
The national contingency planner for DHBs, Anne Aitcheson, told Checkpoint hospitals tried to reduce capacity to about 85 percent, but all but a handful of hospitals had still reached close to 100 percent.
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More than one hospital was about 110 percent capacity, she said.
"People have worked extremely hard to keep very busy hospitals operating," she said.
Aitcheson said the hospitals were busier than intended at the beginning of the day, so there was high acute demand.
"Our EDs have remained very busy all day."
She said no patients were at risk due to a lack of staffing.
"A number of other measures have to be taken. We've cancelled elective surgeries, we've cancelled outpatients' clinics, all routine work has been cancelled so that other people can be directed to work in our emergency departments and on the wards to try and manage the needs of the patients who must be there."
She said it would take months to catch up on the backlog.
"The recovery plans are always very challenging... it's always difficult to catch up."