The "vast majority" of routine operations at Norfolk's largest hospital are being cancelled because of the pressure to deal with the surging number of patients with coronavirus.
The Norfolk and Norwich University Hospital (NNUH) is currently treating more than 200 patients who have been diagnosed with Covid-19, but that means other elective surgery has had to be put on hold.
Erika Denton, NNUH medical director, said the hospital was handling an "extremely challenging" situation and that it had also transferred the vast majority of outpatient appointments to telephone or online consultations.
Speaking to BBC Radio Norfolk, she said: "It is extremely challenging. We have over 200 patients in hospital with Covid and those numbers are increasing every day."
The minor injuries unit at Cromer has been temporarily shut and staff transferred to help at the NNUH, which has also been hit by staff shortages due to them having to isolate due to Covid-19.
Prof Denton said: "We never take lightly having to change what we do, but we have, unfortunately, had to alter quite a lot of things now.
"I am afraid we are having to cancel the vast majority of routine operations at the moment. We just don't have the staff or the space in the hospital.
"We are transferring the vast majority of our outpatient appointments to telephone or online consultations in order to free up staff."
She said the hospital was still dealing with emergencies, such as strokes and heart attacks, but that elective surgery and the outpatients appointments needed to be done differently so staff could focus on the most poorly patients.
Prof Denton said around 800 members of staff had been vaccinated and more would get the jab in the months ahead "at pace".
She said people who had not been contacted to tell them appointments or surgery had been cancelled should still attend hospital.
And she urged people who might have an urgent medical need to make use of the NHS 111 telephone line or website in the first instance.
The hospital is a regional surge centre, which means it is expected to take patients from other areas of the East of England
Prof Denton said there was a small number of patients, particularly from Essex, being cared for on the critical care unit but that the majority of patients were from Norfolk.
She said: "It is extremely worrying that this spike in numbers hasn't yet started to reduce at all."
She said she hoped the new lockdown would have an effect, but that it would take a number of weeks.
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