Objective:
With Victoria’s COVID-19 strategy shifting away from COVID-zero, protecting the health of the population will require achieving high vaccination coverage as quickly as possible, maintaining control of the epidemic to protect the vulnerable, and ensuring that the health system has capacity to provide care to all who need it. An important question is: as vaccine coverage increases, how best can restrictions be eased that prevents health system capacity from being exceeded?
The COVASIM model was used to simulate options for easing of restrictions over the October-December period. Model inputs included data on demographics, contact networks, workforce composition, contact tracing systems and age-specific vaccination rates. As well as options for easing restrictions, additional policies around vaccine allocation and testing were examined to determine potential approaches to further reduce the epidemic peak.
Findings:
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Even without any easing of restrictions, there is a moderate risk of exceeding health system capacity
- Based on the current epidemic growth rate, a peak in 7-day average daily diagnoses of 1400-2900 is estimated to occur between 19-31 October
- Corresponding peaks in hospital and ICU demand were 1200-2500 and 260-550 respectively, with 24% of simulations resulting in hospital demand exceeding 2500 beds.
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In the roadmap scenario, the significant easing of restrictions at 80% vaccine coverage led to 63% of simulations exceeding 2500 hospital demand, and resulted in a second epidemic peak over mid-December
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High rates of symptomatic testing among people who are vaccinated could reduce the impact on the health system
- In a scenario with vaccinated people testing at the same rate as unvaccinated people, the risk of >2500 hospital demand was reduced from 63% to 29%. However, this may be difficult to achieve in practice.
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If a 15% reduction in non-household risk could be achieved and sustained through a variety of additional targeted public health and testing interventions, the risk of >2500 hospital demand could be reduced to 18%
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When 80% adult vaccine coverage is reached, the case numbers, hospital and ICU numbers can provide a guide as to the likelihood of the health system capacity being exceeded and whether restrictions can be safely eased consistent with the roadmap or whether a more staggered approach may be required.
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Due to uncertainty about whether the epidemic growth rate will be sustained, seasonal impacts and vaccine efficacy parameters against the delta strain, updated projections are required as more data becomes available. Decisions to ease restrictions should be based on the latest epidemiological and health system information.
