Almost half a million West Australians will be infected with COVID-19 over a six-month period, long-awaited modelling on the Omicron variant reveals.
Premier Mark McGowan today tabled in parliament a five-page document detailing findings of the modelling conducted by WA Health and the Chief Health Officer Dr Andy Robertson.
The modelling predicts 463,932 people in WA would be infected with COVID-19 in the space of 180 days.
Over those six months, 5,685 people are likely to end up in hospital, 715 are expected to be put into ICU, and 129 West Australians are forecast to ultimately die from COVID-19.
As foreshadowed by the health minister on Friday, the peak of WA's Omicron outbreak is due to hit in late March, with 10,363 new cases in one day.
The peak is expected to see 443 COVID-patients in WA hospitals at one time, and 56 of those people are likely to require intensive care.
Health Minister Amber-Jade Sanderson has said between the public and private hospital systems, WA can cope with this patient load, but it will not be easy.
About three deaths a day are expected to be recorded.
There are expected to be 40 days when more than 200 WA hospital beds are taken up with COVID-patients.
Vaccination rates offer hope
The estimates are described as conservative because WA is significantly more vaccinated than other jurisdictions where Omicron has arrived.
"The actual effect may be lower cases and bed requirements," the document stated.
It is predicated that by March 2, 65 per cent of the WA population aged 16 or over will be triple- dose vaccinated against COVID-19.
The predicted level of tripe-dose vaccination is even higher in more vulnerable age brackets, expected to be over 79 per cent of the population for those aged 50 years and older.
The 70-years-old and above cohort is forecast to be 90 per cent triple vaccinated by March 2.
WA's immunity, taking into account potential waning, is projected to be at its highest in March and coincides with the expected uptrend in case numbers.
'Little to no effect' from border opening
By the time the borders open on March 3, the arrival of interstate and international travellers is predicted to have "little or no effect on the trajectory of the current outbreak".
The number of cases seeded into the community from arriving travellers is expected to be "very low in comparison to the local outbreak".
This is partly attributed to the testing and vaccination requirements on all domestic and international arrivals, as well as the mandatory quarantine for any unvaccinated international arrivals, capped at 70 per week.
WA Health predicts travel into WA will result in 13 daily cases leaking into the community despite RAT testing requirements on arrival, almost half of them asymptomatic.
Interstate travel is forecast to only contribute two daily cases to the community.
The modelling document does not detail what point Level Two social restrictions would be introduced.
Mark McGowan said this morning he would hope to avoid introducing Level Two measures altogether.
But the modelling document warns that removing restrictions too early "will increase the risk of a resurgence in epidemic growth."
Omicron less severe
The modelling assumes "a full reopening of interstate and international borders", and "high numbers of the Omicron strain in the local community".
Based on the experience of other jurisdictions, it is assumed to be unlikely WA Health can maintain "high or medium-level" contact tracing throughout the outbreak.
"Accordingly, the WA Department of Health model projections assume a deterioration in contact tracing efficacy and compliance," the document says.
It says evidence has shown Omicron to be "substantially less severe than the Delta strain, albeit far more transmissible."
Statistical analysis has shown people with the Omicron strain of COVID-19 are 70 per cent less likely to be hospitalised than people with the Delta strain.
It also demonstrates that unvaccinated people are "far more likely to be hospitalised".
The average length of stay for those who are hospitalised is about three to four days with Omicron, compared with eight days for previous strains.
WA in unique position
Studies of household contacts becoming infected suggest that "the intrinsic transmissibility of the virus has increased".
The modelling confirmed multiple studies showed when it comes to Omicron compared with previous strains, vaccines are less effective at preventing infection or the likelihood someone will pass the virus on.
But it also confirmed that vaccines, even with Omicron, continue to be effective in limiting the severity of illness and limiting the likelihood of someone ending up in hospital or ICU.
"Therefore, the susceptibility of the WA population varies significantly depending on the timing of second and third dose vaccinations."
The modelling makes use of estimated waning immunity and actual immunisation data to project the "vaccine-induced immunity" of West Australians over time.
"The WA Health modelling is a highly complex and useful guide to what may happen, taking into account the current outbreak and easing borders on 3 March 2022; however, it is important to note the model is based on a simulation of epidemic growth using a set of scenarios.
"Due to the hard work of all Western Australians, the state is in a unique position and as such there are few (if no) real-world examples from which we can accurately forecast what will occur."
The publishing of the modelling today follows several weeks of intense pressure on the government and WA Health, which insisted repeatedly it was not ready to release it until now.
