Three of the region's hospitals are now treating more coronavirus patients than at the height of the first wave - and the numbers have trebled in a month.
People needing hospital treatment with Covid-19 has gone up rapidly in December and health chiefs and MPs fear worse is to come with rules relaxed from next Wednesday for the five-day Christmas break.
The rise has led to NHS bosses to write an open letter to the people of Norfolk and Waveney in which they say: "We have a monumental challenge on our hands. A challenge that can only be won by each of us making further sacrifice.
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"Sadly, we no longer have the capacity to lower our guard or lessen our resolve over the festive period. We must continue to live with caution and follow guidance fully.
"We therefore ask that you think carefully about your Christmas plans."
Norwich South Labour MP Clive Lewis attacked the government's easing of the rules next week as a "car crash".
Director of Norfolk public health, Dr Louise Smith, said there were 300 people currently in hospital in Norfolk with Covid. That number has trebled since November 10 when there were just 100.
If that trend continues to increase by 200 patients a month, then by February there would be 700 Covid patients needing beds in the county - that is more than the entire capacity of the James Paget University Hospital.
Dr Smith urged people not to meet indoors over Christmas and said on Thursday alone there were another 283 Covid cases recorded in the county.
Latest NHS figures show that this week there were almost 90 coronavirus patients in beds at the Norfolk and Norwich University Hospital (NNUH), surpassing the peak in April of 80.
Norwich North MP Chloe Smith said: "Every in-patient we treat for Covid-19 is a bed and staff taken away from providing all the normal services that the NHS would provide.
"To avoid the very dark situation of not being able to care properly for people with all serious conditions, we have to reduce transmission of coronavirus.”
The situation at the Queen Elizabeth Hospital (QEH) in King's Lynn is similar with 112 Covid patients in beds - again more than the first wave.
Numbers there have risen rapidly this month. On December 1 there were 42 Covid patients in beds at the QEH, but as of Tuesday there were 112.
The rise at the NNUH has been less stark, going from 75 to 87 between the start of the month and Tuesday, but in all the region's hospitals numbers are increasing.
West Suffolk Hospital, in Bury St Edmunds, now has slightly more Covid patients than the first wave, with 44 as of this week.
At the James Paget University Hospital in Gorleston, numbers have not yet hit the peak of April, but it also has around 40 coronavirus patients in beds.
Mr Lewis said: "Health workers, public health experts and academics predicted this outcome several weeks ago.
"What we're seeing now in our hospital is the grisly consequence of the government enabled free-for-all at the end of the first lockdown.
"It is deeply worrying that we're yet to even experience the consequences of the botched ending of second lockdown."
However, fewer patients so far are needing intensive care compared to the first wave. The latest figures show 11 patients on mechanical ventilator beds at Norfolk’s three emergency hospitals, compared to 30 at the height of the first wave.
In October, the NNUH unveiled its plans to cope with a Covid surge over winter.
It said it had enough oxygen to ventilate 300 patients if needed and an “army of reservists”.
The NNUH has also built a unit called a negative pressure isolation unit (NPIU) to take the region’s sickest patients.
A hospital spokesman said: "We are better prepared than the first wave of Covid-19 following our experiences this year and research that has found more effective treatments.
"Our teams are continuing to go above and beyond to maintain services across the Trust during the pandemic."
Across east England, the number of people in hospital beds with Covid is up 70pc in December so far at 1,700.
Of those, 108 are on mechanical ventilator beds, the highest number since May.
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