All non-urgent elective surgery has been cancelled for Tuesday, says Canterbury District Health Board.
It says that includes all pre-arranged admissions for Christchurch Hospital and Christchurch Women's and Burwood hospitals, although scheduled caesarean sections and inductions will continue.
Outpatient clinics are still running and people are advised to come in if they can make their appointment, but it will be rescheduled if they can't.
The board says Akaroa Hospital has been closed and patients transferred.
Some residents in aged-care facilities are also being moved temporarily.
Lincoln Maternity Hospital and Burwood Birthing Unit are closed until further notice.
The health board says the flow of patients to hospital is steady and staff are coping well.
Private hospitals have deferred major surgery to help maintain capacity.
Health authorities continue to urge people to boil water and to avoid contact with sewage.
Relief health workers
Meanwhile, Health Minister Tony Ryall says nurses, community nurses and doctors may need to be sent to Canterbury to relieve those still dealing with the aftermath of the earthquake.
Mr Ryall says extra health workers have already been flown into Christchurch but others could well be needed.
He thanked the hundreds of health workers in Canterbury who spent the weekend treating and caring for those affected by the quake - ahead of tending to their own damaged homes.
He says doctors, nurses and community nurses may be needed from other areas, and he expects to hear from Canterbury District Health Board about that on Tuesday.
In the meantime, a medical officer of health and five health protection officers has arrived from Wellington to help out, along with six Defence Force experts in environmental health and a water sanitation specialist engineer.