Lei Zhang, Monash University; Christopher Fairley, Monash University; Guihua Zhuang, Xi’an Jiaotong University, and Zhuoru Zou, Xi’an Jiaotong UniversityVictoria has entered a five-day lockdown to control its growing outbreak of the more infectious Delta variant.
Until midnight on Tuesday restrictions mean residents are only allowed to leave home for essential reasons, can only travel five kilometres away from home, and need to wear masks outside the home, among other measures.
We consider the lockdown essential and we strongly support this rapid action. However our modelling predicts a five-day lockdown may not be enough.
Instead we predict at least 30 days of restrictions will be needed before Victoria reaches three days without community transmission.
That’s if we take into account current and predicted case numbers, the fact we’re dealing with the more infectious Delta variant, and with current levels of vaccination.
The good news is Victoria is more likely to reach these three “donut days” sooner if vaccination rates pick up, even modestly.
How did we come up with these figures?
We built a mathematical model based on nine COVID-19 outbreaks across four Australian states (including Victoria) since the start of the pandemic. We posted details online as a pre-print. So our model has yet to be independently verified (peer reviewed).
Our model allows us to predict — given current case numbers, the particular variant in circulation and vaccination rates, among other variables — how long public health restrictions such as lockdowns need to last to achieve particular outcomes. Our model also allows us to predict how many cases an outbreak has at its peak.
Models are mathematical tools to predict the future, something of course no-one can do with 100% certainty.
However, our model differs from others because it considers the difference between mystery cases and cases linked to a known case.
It also comprehensively integrates the effects of various public health measures, such as social distancing, wearing masks, contact tracing and vaccination.
What did we find about Victoria?
When we plug data about Victoria’s current outbreak into our model, this is what we find.
Our model predicts the number of daily reported cases of community transmission will continue to climb over the next week or so. Even with the current lockdown we predict a peak of at least 30 cases a day over the next 7-14 days.
We predict the current outbreak will last for at least 30-45 days before Victoria can return to three days of zero community transmission.
However, given the fact Delta is more transmissible than the original Wuhan version of the virus, controlling Victoria’s outbreak will inevitably be more difficult and take longer than dealing with an earlier outbreak of similar size.
New South Wales knows too well how hard it is to get a Delta outbreak under control, something our model predicted.
Back to Victoria, our model supports a hard lockdown that minimises the chance of ongoing transmission.
Strict lockdown (80% reduction in social activities) and mandatory mask use in public spaces and workplaces (90% coverage) — equivalent to what’s expected in Victoria’s current lockdown — have been effective in previous outbreaks in Victoria and other states.
However, we predict the same approaches may only have a 50:50 chance to contain the current Delta outbreak in Victoria.
This means the Delta variant is likely to linger, bouncing at a level of a dozen cases for weeks. This means public health authorities will find it hard to decide how and when to lift restrictions.
Please give me good news
Our model suggests even modest rises in the vaccination coverage in Victoria, by an additional 5% for example, would dramatically increase the chance of controlling the outbreak from 50% to over 80%. If an extra 10% were vaccinated the chance of controlling the outbreak is 94%.
This is because evidence is mounting vaccinated people are less likely to transmit the virus to others. That’s in addition to the vaccines’ well known benefits in reducing your chance of severe disease.
So getting as many Victorians vaccinated as quickly as possible is critical.
What do we make of all this?
Our study conveys a simple message. The battle against the Delta variant in the latest outbreak in Victoria will likely be tough but going early has given us the best chance.
This lockdown will not be as effective as earlier ones in Victoria and coming out of this will need to be carefully managed.
So keeping to the health advice, and vaccinating more Victorians as soon as possible even over the next few weeks, are key to handling this outbreak.
Lei Zhang, Associate Professor of Public Health, Monash University; Christopher Fairley, Professor of Public Health, Monash University; Guihua Zhuang, Professor, Xi’an Jiaotong University, and Zhuoru Zou, Doctor, Xi’an Jiaotong University
Michelle Grattan, University of CanberraThe Morrison and Berejiklian governments have unveiled a joint support package for businesses and workers, as the Sydney lockdown is set to extend to and probably well beyond a fourth week.
But the assistance has set off a row between the Andrews and Morrison governments, with Victoria resentful about its earlier treatment and the federal government accusing it of taking a politicised approach compared with NSW’s constructive one.
As the level of the outbreak continues high in NSW – 89 new cases in the community announced on Tuesday – a support payment will be available for businesses, which is set to cost about $500 million a week. This cost will be equally shared between the federal and NSW governments.
For individuals, from week four of a lockdown in a hot spot declared by the Commonwealth, the COVID disaster payment will rise from $500 to $600 if a person has lost 20 or more hours of work a week. The amount will go from $325 to $375 if the hours lost are between eight and 20.
The payment will also be available to people in NSW outside Commonwealth-declared hotspots where they meet the eligibility criteria – but in these cases the NSW government will fund the cost.
Businesses eligible for assistance will be those with an annual turnover between $75,000 and $50 million, which can demonstrate a 30% decline in turnover, compared with an equivalent two week period in 2019.
Businesses will receive payments ranging from $1,500 and $10,000 a week, based on their payroll, with non-employing businesses such as sole traders receiving $1000 a week.
Up to 500,000 entities are expected to be eligible, which employ more than three million people. The assistance will be available to not-for-profit entities. Those receiving the payment will have to maintain their workforces at current levels.
Scott Morrison, speaking at a news conference with NSW premier Gladys Berejiklian and state treasurer Dominic Perrottet, said the aid would go as long as the lockdown required.
The federal government – under earlier criticism for being more anxious to help NSW than it had been to assist Victoria, when it was slow with an announcement – emphasised that the new payments would apply to other states if they were to be in similar circumstances.
But the Victorian government reacted sharply.
“Victorians are rightly sick and tired of having to beg for every scrap of support from the federal government,” a spokesperson said in a statement.
“It shouldn’t take a crisis in Sydney for the Prime Minister to take action but we are seeing the same double standard time and time again. His job is not to be the Prime Minister for NSW.
“We had to shame the federal government into doing their job and providing income support for Victorian workers when we battled the Delta strain earlier this year. Their position at the time was a disgrace.
“If they had bothered to think about this at the time and work with Victoria, they’d already have had a practical framework in place when NSW went into lockdown and more people would have got the support they need earlier,” the statement said.
The Morrison government hit back, contrasting what it described as different attitudes by Victoria and NSW.
“The NSW government has worked constructively with the Commonwealth to support their households and businesses while the Victorian government’s politicised approach has unfortunately been to issue decrees by media instead of picking up the phone to find solutions as a partnership,” a federal spokesperson said.
The spokesperson said Victorian received the same support for its two week circuit breaker lockdown as had NSW for its first two weeks.
“As the pandemic has evolved and as the situation in NSW has gone beyond those two weeks, the Commonwealth’s support has also evolved. If Victoria were to go into another extended lockdown, it would receive the same support as is being offered to NSW.”
The spokesperson said that during the recent Victorian lockdown, the Commonwealth offered to share all costs with the state. “Victoria declined, and asked for the Commonwealth to handle income support while they would support businesses.”
Treasurer Josh Frydenberg told the ABC on Tuesday night, people were sick of Victorian Premier Dan Andrews’ “whingeing”.
Under the package for NSW, the Commonwealth is providing some business tax relief and the NSW government is giving some payroll relief and protection against evictions.
The package also contains $17.35 million for mental health support. Among organisations to receive funding will be headspace and Kids Helpline.
The Australian Technical Advisory Group on Immunisation (ATAGI) on Tuesday released new advice on AstraZeneca in light of the Sydney outbreak.
It said in the context of an outbreak where the supply of Pfizer was constrained, people under 60 who don’t have immediate access to Pfizer should “reassess the benefits to them and their contacts from being vaccinated with COVID-19 Vaccine AstraZeneca, versus the rare risk of a serious side effect”.
It also said in outbreak situations those who had received a first AZ shot more than four weeks ago should get their second dose as soon as possible, rather than waiting the preferred 12 weeks.