"We've had an average of 200 staff off with Covid-19 every day for some weeks now," she said.
"This is in addition to high levels of sick leave being taken by health staff right across the system for other illnesses and to care for dependents.
"With flu now circulating in Canterbury there's another serious virus out there affecting staff and the wider community."
Christchurch Hospital's chief of surgery Greg Robertson said surgical teams are extremely disappointed at having to defer people's surgery, often at short notice.
"We don't take these decisions lightly, and each case is carefully considered before a decision to defer is made," Robertson said.
"We were just starting to gear up again after our Covid-19 surgery slowdown, and this week our hospitals are full of very unwell people with a range of medical and surgical conditions.
"We're currently sitting at 112 per cent occupancy which means we have more patients than resourced beds, so our focus is on increasing the flow of patients through our system."
Christchurch Hospital ED is seeing high numbers of people (380 people in the past 24 hours) and 30 per cent of those coming to ED are so unwell they need to be admitted to hospital. It means that available beds are filling up fast and there's no additional capacity to accommodate planned surgical patients.
"Reducing the amount of planned surgery we carry out is the only way we can continue to provide safe care to those who need it," Robertson said.
"To those whose surgery has been deferred today, and to those we will have to postpone this week please accept my sincere apologies on behalf of the team. I know how disappointing and disruptive it is to hear that news.
"Once we have passed this period of intense acute demand, we will start rebooking people when we can have greater confidence that their surgery will be able to go ahead. We are working with the private hospitals in Canterbury to increase surgical capacity wherever possible. All we can say is sorry, as right now we need to focus our efforts of people coming through the front door needing hospital level care, while preserving some capacity for acute (unplanned) surgery."
The CDHB says it's not too late for people to get their flu vaccination, Covid-19 booster or MMR immunisations.
"By having your vaccinations and staying well this winter, you'll help keep health services free for those who need urgent care," Hickmott added.
