More than 7000 COVID-19 patients will need hospital treatment in the next four weeks and hundreds will die if social distancing measures do not change the disease's trajectory in the Hunter New England Health district.
Nurses and doctors at John Hunter Hospital were briefed late last week to prepare for a weekly quadrupling of hospital admissions to 3840 by April 22 and more than 1000 intensive care cases.
Using the latest HNEH figures, the number of people in the district who have contracted the coronavirus could rise from 189 on Saturday night to 48,384 by Saturday, April 25.
The district had 47 confirmed cases one week ago.
Using the ratios presented to medical staff, 15 per cent, or 7257, of those who could be infected by Anzac Day would end up in hospitals and 4 per cent, or 1935, in intensive care units.
John Hunter Hospital, by far the HNEH region's largest health facility, normally has 24 beds in its adult ICU.
Based on a mortality rate of 1 per cent, 483 of the 48,300 would die of COVID-19, and there is no guarantee case numbers will not keep rising beyond April.
A report published on Saturday by the UK's Intensive Care National Audit & Research Centre showed 47.9 per cent of COVID-19 patients in British ICUs did not survive, including 37.5 per cent of women and 53.2 per cent of men. Seventy per cent of COVID-19 patients in ICU were men.
A quarter of patients aged 16 to 49 in ICU did not survive. The death rate of ICU patients aged 50 to 69 was 40 per cent, rising to 73 per cent for those aged over 70. Two-thirds of all patients placed on a ventilator died.
HNEH public health director Dr David Durrheim said the projected case numbers in the district were not a fait accompli and it was unknown what effect social distancing and better hygiene would have on transmission.
He said most cases in the Hunter were linked to cruise ships or overseas travel rather than community transmission, a factor which could delay the disease's spread.
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But the potential for the numbers to rise exponentially showed the need for the public to observe strict social distancing and hygiene.
"What we've got to do is distance now or all those numbers could get quite frightening. We don't want to be Italy," Dr Durrheim said.
"Australia's really at a critical time. We see that Australia's doubling time is in that dangerous three-and-a-half days.
"What we want to do is through these measures really slow it and make ourselves Singapore rather than an Italy or the United States.
"That's a decision that we as a community face. We all have a role to play."
NSW's Chief Health Officer, Dr Kerry Chant, said two weeks ago that the state was anticipating 1.5 million people could be infected.
Australia has more than 3800 confirmed cases and a relatively low 16 deaths, but Dr Durrheim said people had to prepare for the mortality rate to climb. He said COVID-19 patients typically died two to three weeks after developing symptoms.
"We look at the death rates and it's promising, but the death rates lag behind case numbers because those who are sick may still deteriorate," Dr Durrheim said.
"We've given the hospital system time to get ready.
"It's inevitable that there will be community spread, and we know that that will place a big burden on the health service, so the longer we can flatten that curve and rather have a trickle-in of cases, lives will be saved."
The virus was "one doubling time" ahead of the statistics because it took several days for people to feel ill and get tested, suggesting twice as many have the virus than the numbers suggest.
"Unfortunately, at the moment there are some portals of community transmission in Australia and so it's inevitable that the virus will spread," Dr Durrheim said.
HNEH medical controller Paul Craven said the hospital system was clearing ward space, training "surge" staff who do not usually work in ICU, gathering protective equipment and examining spill-over options.
"We're day 62 into this, so we've been meeting constantly all day every day," Dr Craven said.
"We know all our acute beds, all our ICU beds, all our surge beds, if we have to increase numbers of our ICU beds, where they would be.
"We've seen it where they've set up camps and taken over entertainment centres and things like that.
"We've had some very, very provisional conversations about that ... there's tents and larger facilities."
He said large orders of vital protective equipment were arriving and he was comfortable with the health service's stocks "if that all goes well".
Dr Durrheim applauded HNEH for being "very open and frank with staff".
"I don't think we should put our head in the sand. This will be a massively challenging next couple of months.
"I think the district is absolutely right to prepare for a worst-case scenario. This is going to be yours and my next-door neighbour, family, close friend who is going to need those facilities."