How contagious is Delta? How long are you infectious? Is it more deadly? A quick guide to the latest science


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Lara Herrero, Griffith UniversityDelta was recognised as a SARS-CoV-2 variant of concern in May 2021 and has proved extremely difficult to control in unvaccinated populations.

Delta has managed to out-compete other variants, including Alpha. Variants are classified as “of concern” because they’re either more contagious than the original, cause more hospitalisations and deaths, or are better at evading vaccines and therapies. Or all of the above.

So how does Delta fare on these measures? And what have we learnt since Delta was first listed as a variant of concern?




Read more:
Is Delta defeating us? Here’s why the variant makes contact tracing so much harder


How contagious is Delta?

The R0 tells us how many other people, on average, one infected person will pass the virus on to.

Delta has an R0 of 5-8, meaning one infected person passes it onto five to eight others, on average.

This compares with an R0 of 1.5-3 for the original strain.

So Delta is twice to five times as contagious as the virus that circulated in 2020.



The Conversation, CC BY-ND

What happens when you’re exposed to Delta?

SARS-CoV-2 is the virus that causes COVID-19. SARS-CoV-2 is transmitted through droplets an infected person releases when they breathe, cough or sneeze.

In some circumstances, transmission also occurs when a person touches a contaminated object, then touches their face.

Four Turkish men walk across an open town space.
One person infected with Delta infects, on average, five to eight others.
Shutterstock

Once SARS-CoV-2 enters your body – usually through your nose or mouth – it starts to replicate.

The period from exposure to the virus being detectable by a PCR test is called the latent period. For Delta, one study suggests this is an average of four days (with a range of three to five days).

That’s two days faster than the original strain, which took roughly six days (with a range of five to eight days).



The Conversation, CC BY-ND

The virus then continues to replicate. Although often there are no symptoms yet, the person has become infectious.

People with COVID-19 appear to be most infectious two days before to three days after symptoms start, though it’s unclear whether this differs with Delta.

The time from virus exposure to symptoms is called the incubation period. But there is often a gap between when a person becomes infectious to others to when they show symptoms.

As the virus replicates, the viral load increases. For Delta, the viral load is up to roughly 1,200 times higher than the original strain.

With faster replication and higher viral loads it is easy to see why Delta is challenging contact tracers and spreading so rapidly.

What are the possible complications?

Like the original strain, the Delta variant can affect many of the body’s organs including the lungs, heart and kidneys.

Complications include blood clots, which at their most severe can result in strokes or heart attacks.

Around 10-30% of people with COVID-19 will experience prolonged symptoms, known as long COVID, which can last for months and cause significant impairment, including in people who were previously well.

Woman in a mask waits in hospital waiting room.
Even previously well people can get long COVID.
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Longer-lasting symptoms can include fatigue, shortness of breath, chest pain, heart palpitations, headaches, brain fog, muscle aches, sleep disturbance, depression and the loss of smell and taste.

Is it more deadly?

Evidence the Delta variant makes people sicker than the original virus is growing.

Preliminary studies from Canada and Singapore found people infected with Delta were more likely to require hospitalisation and were at greater risk of dying than those with the original virus.

In the Canadian study, Delta resulted in a 6.1% chance of hospitalisation and a 1.6% chance of ICU admission. This compared with other variants of concern which landed 5.4% of people in hospital and 1.2% in intensive care.

In the Singapore study, patients with Delta had a 49% chance of developing pneumonia and a 28% chance of needing extra oxygen. This compared with a 38% chance of developing pneumonia and 11% needing oxygen with the original strain.

Similarly, a published study from Scotland found Delta doubled the risk of hospitalisation compared to the Alpha variant.

Older man with cold symptoms lays down, wrapped in a blanket, cradling his head, holding a tissue to his nose.
Emerging evidence suggests Delta is more likely to cause severe disease than the original strain.
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How do the vaccines stack up against Delta?

So far, the data show a complete course of the Pfizer, AstraZeneca or Moderna vaccine reduces your chance of severe disease (requiring hospitalisation) by more than 85%.

While protection is lower for Delta than the original strain, studies show good coverage for all vaccines after two doses.

Can you still get COVID after being vaccinated?

Yes. Breakthrough infection occurs when a vaccinated person tests positive for SARS-Cov-2, regardless of whether they have symptoms.

Breakthrough infection appears more common with Delta than the original strains.

Most symptoms of breakthrough infection are mild and don’t last as long.

It’s also possible to get COVID twice, though this isn’t common.

How likely are you to die from COVID-19?

In Australia, over the life of the pandemic, 1.4% of people with COVID-19 have died from it, compared with 1.6% in the United States and 1.8% in the United Kingdom.

Data from the United States shows people who were vaccinated were ten times less likely than those who weren’t to die from the virus.

The Delta variant is currently proving to be a challenge to control on a global scale, but with full vaccination and maintaining our social distancing practices, we reduce the spread.




Read more:
Why is Delta such a worry? It’s more infectious, probably causes more severe disease, and challenges our vaccines


The Conversation


Lara Herrero, Research Leader in Virology and Infectious Disease, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Vital Signs: we’re doing well despite Delta, but 3 major economic challenges loom


Richard Holden, UNSWThis week the Organisation for Economic Co-operation and Development published its first “Economic Survey of Australia” since 2018.

It gives Australia good marks for a remarkably good economic response to the COVID pandemic, but warns of the importance of not shirking reforms needed for long-term prosperity.

The Reserve Bank of Australia’s governor, Philip Lowe, also addressed Australia’s recovery this week, in a speech to the Anika Foundation, which funds research into adolescent depression and suicide. Lowe has made a speech annually since 2017 to help raise funds for the foundation, as his predecessor Glenn Stevens also did.

Lowe was upbeat about Australia’s recovery from the pandemic, and also had important observations about Australia’s economic outlook.




Read more:
Four GDP graphs that show how well Australia was doing – before Delta hit


He emphasised the central bank would not be lifting interest rates to curtail the latest spike in house prices. The OECD report warns the Australian government relies too much on income taxes for revenue. It also argues forcefully for the significant economic benefits in Australia doing more to reduce carbon emissions.

Taken together, these two assessments point to the outstanding job done in managing the economic recovery.

But they also tell us we will have economic problems down the road if three big, structural reform areas — housing affordability, the tax mix, and decarbonisation — are not addressed.

Recovery signposts

In his speech on Tuesday, Lowe painted a helpful picture of the path of Australia’s recovery before the Delta outbreak — with the unemployment rate hitting a 20-year low and GDP growth recouping all its 2020 losses.

At the end of the June quarter, domestic final demand was more than 3% above its pre-pandemic level. GDP was up close to 10% for the previous 12 months.


Australia’s gross domestic product, seasonally adjusted

Australia's gross domestic product, seasonally adjusted

ABS, Australian National Accounts: National Income, Expenditure and Product, June 2021

The recovery of the labour market was even more impressive. As Lowe put it:

In June, the employment-to-population ratio reached a record high of 63% and the unemployment rate fell to 4.9%, the lowest it had been in more than a decade.

The momentum in the labour market was so strong that in July the unemployment rate dropped to 4.6%, despite Delta-related lockdowns in greater Sydney.


Australia’s unemployment rate, seasonally adjusted

Australia's unemployment rate, seasonally adjusted
Australia’s unemployment rate, seasonally adjusted.
ABS, Labour Force Survey, August 2021

Delta thoughts

Lowe went on to discuss the economic hit of Delta.

Of course, how big that hit is depends on vaccination rates and how safely NSW and Victoria reopen. At a time when there’s a fair bit of discussion of best-case scenarios, Lowe warned of grimmer possibilities, warning of the possibility of:

further significant restrictions on activity […] in response to new outbreaks of Delta, the emergence of a new strain of COVID-19 or a decline in the potency of the current vaccines.

What Lowe hinted at, but didn’t say, was that, absent the Delta outbreak in Australia, the recovery would have continued to drive GDP up and unemployment down.




Read more:
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“On the economy,” Lowe said, “our central message is that the Delta outbreak has delayed – but not derailed – the recovery of the Australian economy. If that turns out to be correct then unemployment could fall below 4% by early 2023 — though how far below remains to be seen.

It’s worth remembering that had the federal government not bungled its vaccine buying and roll-out strategy, Australia might have avoided the current economic pain.

Finally, Lowe was emphatic the central bank would not be raising interest rates to “cool the property market”:

I want to be clear that this is not on our agenda. While it is true that higher interest rates would, all else equal, see lower housing prices, they would also mean fewer jobs and lower wages growth. This is a poor trade-off in the current circumstances.

That’s Lowe-speak for: “Read my lips — no interest rate hikes until 2024.”




Read more:
Vital signs: to fix Australia’s housing affordability crisis, negative gearing must go


OECD’s report card

The hefty OECD report (about 130 pages) concurs with Lowe’s view on strength of Australia’s pandemic recovery. It essentially congratulates the government for its response, noting “fiscal policy has responded with unprecedented force”.

OECD Economic Surveys: Australia, 2021 report cover
OECD Economic Surveys: Australia, 2021.
OECD

But it also notes the low rate of Australia’s goods and services tax (GST) compared to consumption taxes in other countries, leaving the federal government (and thereby state and territory governments) reliant on personal income taxes.

The report observes that GST revenue as a share of total taxation has been falling — from 15.4% in 2003-04 to 14.1% in 2020-21. It suggests increasing the rate of GST would lead to a more efficient tax mix.

This puts both side of politics squarely on notice that serious tax reform needs to be on the agenda soon.

The OECD report also emphasises the importance of the Australian economy decarbonising more rapidly. This is another big policy reform on which the government has show little inclination to take stronger steps.

Common threads

So the RBA and OECD both point to Australia’s strong pandemic recovery, driven in large part by the fiscal force of programs such as JobKeeper and JobSeeker.

The Delta outbreaks have put a serious dent in this recovery. But there is reason to believe the recovery will be back on track by early 2022. In the longer term, though, there will have to be a reckoning about major structural reforms.

By 2050 we will need to have a largely decarbonised economy. We are also going to need to have an improved tax mix to drive innovation. And sooner rather than later the housing affordability crisis must be addressed.The Conversation

Richard Holden, Professor of Economics, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Languishing, burnout and stigma are all among the possible psychological impacts as Delta lingers in the community


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Dougal Sutherland, Te Herenga Waka — Victoria University of WellingtonAs New Zealand remains under different levels of restriction, the psychological toll of the Delta outbreak may start to show, even as lockdown eases for everyone outside Auckland.

We know that stress and isolation associated with a lockdown can exacerbate underlying mental illnesses. But even for people with no existing concerns, the impact can show in more subtle ways, on a continuum between flourishing and languishing.

Imagine a t-shaped cross with symptoms of mental illness on the horizontal axis ranging from severe to none, and mental health on the vertical axis, ranging from high (flourishing) to low (languishing). Under this model, it’s quite possible to experience a mental illness but still be flourishing or to have no symptoms of a mental illness, yet be in a state where life feels dull and meaningless.

Increased levels of languishing were reported in the UK as extended lockdowns continued. New Zealanders, especially in Auckland, are at risk of experiencing a similar decline in their mental health as the groundhog days of an extended lockdown continue.

Essential workers at risk of burnout

For health workers, extended lockdowns come with a risk of professional burnout. Health Minister Andrew Little recently noted the high levels of stress experienced by nurses and doctors as they continue to provide care in trying circumstances.

The World Health Organization defines burnout as mental and physical exhaustion, feelings of cynicism and detachment from work, and a loss of productivity.

Prior to lockdown, nurses were on the verge of strike action, spurred on by high levels of reported burnout. The ongoing demand due to COVID-19 is unlikely to alleviate this.




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Six evidenced-based ways to look after your mental health during another lockdown


Recent media comments regarding the well-being of Prime Minister Jacinda Ardern and Director-General of Health Ashley Bloomfield remind us that public servants are not immune either. Nor are essential workers such as truck drivers and supermarket workers. The latter in particular are at increased risk because of abuse they suffer from irritated shoppers and the shock linked to the recent supermarket terror attack.

Vaccination may ease anxiety

As more people become fully vaccinated, people’s perception of threat linked to an outbreak is likely to diminish. So, too, are our levels of anxiety, if overseas experience is anything to go by.

This shift in the public mindset is logical and would signal a step towards us learning to live with COVID-19 in the same way perhaps as we have learnt to live with other diseases. But experience to date suggests this transition is likely to have some ups and downs, with the ongoing potential emergence of new COVID-19 variants.

As vaccination rates rise, there is also a risk that media and the public begin to stigmatise identifiable groups who haven’t been vaccinated, blaming them for the spread of the virus and a loss of liberty. New Zealand had a taste of this recently when one cluster of the Delta outbreak was linked to a Samoan church, triggering online racist comments blaming them for the lockdown.

These types of comments increase the suffering of those already affected by the virus. They also overlook the evidence for substantial inequities in access to healthcare.

But languishing, burnout and stigmatisation are not inevitable consequences of an ongoing lockdown. Noticing changes in your own mental health is the first step to preventing a slide into languishing.




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Sir Mason Durie’s Te Whare Tapa Wha model is an excellent framework to guide this self-reflection. It provides a holistic model of well-being covering mental, physical, social and spiritual domains.

To help combat burnout, a simple step we can all take is to show appreciation to essential workers. In 2020, public displays of support for healthcare workers were widespread in other parts of the world, but less common in New Zealand.

Now is the time to thank our supermarket workers, truck drivers, public servants, doctors and nurses who continue to serve us. Demonstrating that these workers are valued can help buffer against professional burnout as they feel more engaged and satisfied with their work.

Understanding more about disparities in our health system — and reminding ourselves that COVID-19, not specific groups of people, is the problem — is another step towards reducing stigma. Taking these small steps can help all of us us flourish, regardless of what the virus throws at us.The Conversation

Dougal Sutherland, Clinical Psychologist, Te Herenga Waka — Victoria University of Wellington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

There’s no need to panic about the new C.1.2 variant found in South Africa, according to a virologist


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Ian M. Mackay, The University of QueenslandScientists in South Africa have discovered a new viral variant of SARS-CoV-2, the virus that causes COVID-19.

It’s not a single virus but a clustering of genetically similar viruses, known as C.1.2.

The researchers, in a pre-print study released last week but yet to be peer reviewed, found this cluster has picked up a lot of mutations in a short period of time.

Indeed, this is what viruses do. They continually evolve and mutate due to selective pressures but also because of opportunity, luck and chance.

C.1.2 has some concerning individual mutations. But we don’t really know how they’ll work together as a package. And it’s too early to tell how these variants will affect humans compared with other variants.

There’s no need to panic. It’s not spreading widely, and it’s not at Australia’s doorstep. The tools we have in place work against SARS-CoV-2, whatever the variant.

Will it be more infectious or severe?

C.1.2 is distinct from but on a genetic branch near the Lambda variant, which is common in Peru.

It has some concerning individual mutations. But we don’t know how these mutations will work altogether, and we can’t predict how bad a variant will be based on mutations alone.

We need to see how a certain variant works in humans to give us an idea of whether it’s more transmissible, causes more severe disease or escapes the immunity we get from vaccines more than other variants.

At this stage we don’t know enough about how C.1.2 behaves in humans because it hasn’t spread enough yet. It represents less than 5% of new cases in South Africa, and has only been found in around 100 COVID cases worldwide since May.

It’s not yet listed by the World Health Organization as a variant of interest or a variant of concern.




Read more:
The Lambda variant: is it more infectious, and can it escape vaccines? A virologist explains


Will it overtake other variants?

It’s early days, so it’s impossible to predict what will happen to C.1.2.

It could expand and overtake other variants, or it could fizzle and disappear.

Again, just because this virus has a bunch of mutations, it doesn’t necessarily mean the mutations will work together to out-compete other variants.

Delta is the kingpin variant at the moment, so we need to keep an eye on C.1.2 to see if it starts to push out Delta.

So, it’s important to keep watching it in case it starts transmitting widely. One group in Australia, the Communicable Diseases Genomics Network, monitors these developments closely.




Read more:
Why is Delta such a worry? It’s more infectious, probably causes more severe disease, and challenges our vaccines


There’s no need to panic

At this point, there’s no need for concern.

Australia still has its border restrictions in place, so the odds of this rarely occurring virus coming into the country and spreading are very low.

There’s no evidence our vaccines don’t work against it. Our vaccines provide protection from severe disease and death against all other SARS-CoV-2 variants thus far and there’s a good chance they’ll continue to do so against C.1.2 variants.




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What’s the difference between mutations, variants and strains? A guide to COVID terminology


It won’t be long until we have a better idea of how C.1.2 behaves. There’s a lot of eyes on it, and we need to have patience as the data comes in.

Sensationalism and panic in the meantime isn’t going to solve anything.

New variants, and other bits of news amid the pandemic, are often latched onto and amplified by certain people and media. There’s a real risk this causes fear when it’s not needed, and inducing fear is a form of harm.

It is a tough time for the public because it’s hard to know who to listen to and trust.

I would say it’s best to listen to the experts, particularly organisations whose job it is to track and communicate risks about these things, like the WHO and your local jurisdiction’s health department.

Don’t amplify or pay attention to obvious alarmism and extreme negativity, and make sure you’re getting your information from media sources that are trustworthy.

Vaccination remains our best single tool

The chances of new variants arising increases the more the virus spreads.

Vaccinating as many people as possible, as quickly as possible, is key to reducing the risk of new variants arising.

That’s not to say it will reduce the risk to zero and there will be no more variants. Mutations happen by chance, and happen in a single person. One way mutations can arise is in people whose immune systems are compromised — they mount an incomplete immune response and the virus adapts, escapes and is released with more mutations.

Nothing is perfect in biology. People’s immune systems respond in different ways, and a lot is based on individals’ immune history — how competent their immune system is and whether they have chronic disease.

We also won’t have every single person fully vaccinated, and vaccines aren’t 100% perfect, so there will still be some spread of the virus.

But vaccination reduces the risk a lot. We also know what else works to limit this virus, including ventilation, filtering air, masks and social distancing measures.The Conversation

Ian M. Mackay, Adjunct Associate Professor, Faculty of Medicine, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Masks, ventilation, vaccination: 3 ways to protect our kids against the Delta variant


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Katrina McLean, Bond University and Natasha Yates, Bond UniversityLast year in the COVID-19 pandemic, children were not catching or spreading the virus much. The main focus was on protecting our elderly and vulnerable.

But the Delta strain has changed things. Children around the world are contracting Delta in high numbers and some frontline doctors believe they may also be getting sicker from this strain.

Many parents and schools have concerns about how to best protect children from COVID-19. There’s also the worry children will catch the virus at school and take it back to their families and communities.

While many children are now well-accustomed to washing and sanitising their hands, this is simply not enough to tackle the spread of COVID-19, especially now we know the virus is airborne. We need a whole toolbox of strategies.

There are three key areas to focus on that we believe are evidence-based, easy to implement and will help protect our children: masks, ventilation and vaccination.

1. Masks

In certain Australian states, children aged 12 and above are currently required to wear a mask in public areas (schools included).

Meanwhile, Victoria’s chief health officer Brett Sutton has recommended children aged five and up wear masks in the face of rising Delta transmission among children.

As GPs, parents often ask us if it’s safe for children to wear masks. While we understand concern from parents, we reassure them masks have been found to cause no harm in children over the age of two. When children wear masks it doesn’t affect their breathing or reduce their oxygen levels.

Importantly, when worn properly, masks are effective at reducing the spread of COVID-19, for adults and children alike.




Read more:
Under-12s are increasingly catching COVID-19. How sick are they getting and when will we be able to vaccinate them?


A few quick tips. Fabric masks should be treated like underwear: wash them regularly, ensure they cover everything, and don’t share. These are a better option for the environment.

Label fabric masks like school hats — they will go missing!

Surgical/disposable masks are single use. Like using a tissue to blow your nose, make sure it goes in the bin once used and then wash your hands.

And masks should fit snugly — the less gaps there are the better they will work.



Like anything new, getting used to masks can take time. Children may initially be anxious, especially if their parents are too. Though most kids adapt really quickly (much quicker than adults, in our experience).

While the majority of children will adapt quickly there will be some who have specific and legitimate concerns, for example disabilities and sensory issues. GPs and paediatricians can help work out what the safest approach is for these children.

2. Ventilation

SARS-CoV-2, the virus that causes COVID-19, can float in the air like smoke. If you’re inside in a small enclosed room with other people and the ventilation is poor, it will only be a matter of time before you’re all breathing in each other’s air.

Schools have lots of children inside enclosed classrooms, often for hours, so what can be done?

Ventilation is something schools can and should address. Some simple strategies include:

  • get outside as often as is practical. Call children into the classroom only once the day has started. Hold some lessons outside the classroom. During breaks and lunch time children should be outside whenever possible too
  • open doors and windows
  • set air conditioning or heating systems to bring in as much outdoor air as possible
  • check the air with carbon dioxide monitors. This is occurring overseas.

Why do we care about CO₂? Well, we breathe in oxygen and breathe out CO₂. In confined spaces with lots of air that has been “breathed out”, monitors will detect higher levels of CO₂.

All that “breathed out” air could be full of viral particles, so if the monitor is measuring high, airflow needs to be improved immediately by opening a door or window.

In stuffy rooms, or rooms that measure high for CO₂ (indicating the ventilation is poor), a longer-term plan to clean the air should be considered. What’s encouraging is that the technology already exists to address this.

Air cleaners, also known as air purifiers, scrubbers, or HEPA filters, can actually help to “clean” the air we breathe. Lots of schools around the world are now actively improving ventilation systems and air quality monitoring.

Improving the air quality in schools may also prevent some of the other colds and flus kids pick up at school, and reduce asthma and allergy symptoms.

3. Vaccination

At this stage in Australia the Pfizer vaccine is recommended for vulnerable children aged 12-15, including those registered on the National Disability Insurance Scheme.

Vaccinations for all children 12 and over are now under way in New Zealand.

New Zealand GP Dr Sarah Hortop shared this photo of her daughters who received their first dose of the Pfizer vaccine recently.
Sarah Hortop, Author provided

Many other countries have been giving vaccines to children for several months now. For example, in the United States, more than one-third of 12 to 15-year-olds are fully vaccinated and nearly 50% have had at least one dose.

We know the vaccines work well in this age group and just like in adults, there is very close monitoring of adverse events from these vaccines in children. It’s reassuring to see very few serious reactions, and even those that are (for example myocarditis — inflammation of the heart) are treatable.

Vaccine trials are under way in children under 12 in the US (for Pfizer and Moderna), and once we have the safety and efficacy data we can start making decisions around vaccinating them too.




Read more:
We should install air purifiers with HEPA filters in every classroom. It could help with COVID, bushfire smoke and asthma


The Conversation


Katrina McLean, Assistant Professor, Medicine, Bond University and Natasha Yates, Assistant Professor, General Practice, Bond University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Grattan on Friday: As COVID’s third wave worsens, Scott Morrison pivots to the future


Michelle Grattan, University of CanberraJosh Frydenberg is Scott Morrison’s house guest at The Lodge – sharing, in Canberra’s lockdown, microwaved meals and watching “Yes, Prime Minister”.

As he recounted domestic life with Scott, the treasurer was inevitably asked whether he’d measured up the curtains.

Among the ministers, Frydenberg and Health Minister Greg Hunt have carried the frontline burdens during the pandemic. For Frydenberg – the biggest-spending federal treasurer in the nation’s history – the experience can be viewed as a test for future leadership.

Although there’ve been mistakes – JobKeeper had design flaws which led to serious waste – he has come through creditably in extraordinary circumstances.

Frydenberg, who is also deputy Liberal leader, has never hidden his ambition and is hungry for the top job. But he is also loyal. Morrison knows that, unlike prime ministerial predecessors Tony Abbott and Malcolm Turnbull, he doesn’t have to look over his shoulder, even in the bad times. Morrison marked three years as PM this week, and there has been no white-anting.

There’s more than one path to the prime ministership for Frydenberg. If Morrison loses the election, Frydenberg would be favourite to become leader of the opposition. But that’s the start of a very rocky road; hard work and high hopes can be dashed, as Bill Shorten found.

An alternative path is to be well placed vis-a-vis your internal competitors and inherit the post when it becomes available, one way or another.

If the Coalition is re-elected next year, would Morrison serve a full term, or is it possible he might leave triumphant after a couple of years, not risking the gamble on a third election “miracle”? Frydenberg knows Morrison’s moving on in a smooth transition would be his best prospect.

The prime minister this week was in full campaign mode for the March or May election and we had a glimpse of the formidable fighter we saw in 2019.

In a week when the NSW government lost control of COVID, the state’s daily new cases rising above 1,000 and hospitals under severe strain, and with Victoria on the brink, Morrison made a dramatic pivot to focus on opening the country.




Read more:
View from The Hill: Achieving vaccine targets could be followed by a (pre-election) health ‘pinch point’


Embattled NSW Premier Gladys Berejiklian was firmly in step, making it clear she’s determined to move when the 70% vaccine target is reached (meanwhile announcing some minor easings).

It seemed incongruous that as the third wave deepened and with only a third of eligible people fully vaccinated, Morrison simply left the bad news behind and headed for the ground on which he wants to stand. In his Thursday news conference, for example, he began by hailing “another day of hope”, based on the latest vaccination numbers.

Morrison, backed by research, judges most voters have had enough of lockdowns and blocked internal travel.

A poll published by Nine this week showed 54% believed Australia could not completely suppress COVID, and more than six in ten favoured opening up once the target vaccination thresholds were reached. In the second year of the pandemic, public opinion appears to have swung from preoccupation with the health response to a strong desire to return to more freedom.

While Morrison pivots when in political trouble, Anthony Albanese this week looked to be lumbering. With the PM accusing the opposition leader of undermining the national cabinet’s exit plan, Albanese knew he had to get himself out of that corner. He stressed support for the plan, but his demeanour was that of a man on the back foot.

The defiant premiers of Queensland and Western Australia are in an easier short-term position. WA’s Mark McGowan, in particular, with his stratospheric popularity, can tell Morrison to go jump, as in effect he did this week. After the PM invoked “The Croods” film to say we must emerge from the cave, McGowan played heavily to West Australians’ parochialism and angst towards the east.

“This morning the prime minister made a comment implying Western Australians were like cave people from a recent kids’ movie. It was an odd thing to say,” McGowan wrote on Facebook. “I think everyone would rather just see the Commonwealth look beyond New South Wales and actually appreciate what life is like here in WA.

“We currently have no restrictions within our State, a great quality of life, and a remarkably strong economy, which is funding the relief efforts in other parts of the country.

“West Aussies just want decisions that consider the circumstances of all States and Territories, not just Sydney.”

Regardless of the national plan to which they agreed, McGowan and Annastacia Pałaszczuk have the constitutional and political authority to handle their states’ transitions as they see fit. But they can’t get away from the fact they’ll have to make the journey, relaxing border restrictions, at some stage.




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As New Zealand is now finding, a zero-COVID position, however assiduously pursued, seems an impossible dream over the longer term.

Without the sharp motivators of big outbreaks, WA and Queensland have vaccination rates lower than the national average, and health systems that haven’t been stress-tested under maximum COVID pressure. WA, self-sheltered for so long, would be especially vulnerable if there were a big outbreak.

At the national level, one political unknown is what the public reaction will be in the difficult transition period ahead. Will sentiment change again when there are more hospitalisations and deaths as we reopen, albeit with some continuing safeguards?

With the length of the current extensive lockdowns unknown, it is not clear whether by election time we’ll have had, or have escaped, another recession. We know this September quarter will be negative but the December quarter could go either way.

Two consecutive quarters of negative economic growth (the economy shrinking) is taken in technical terms to be a recession. AMP economist Shane Oliver says there is a 45% chance of negative growth in the June-quarter figures, which will be released next Wednesday. If that happened a recession would be certain.

At the election the economy and fiscal policy will be central issues. If we are as “open” as the prime minister foreshadows, the government will need to have plans for when and how it would start fiscal repair.

For Morrison and Frydenberg, this will be another pivot point. Many will be watching carefully how much agility the treasurer can show.




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Politics with Michelle Grattan: Doherty’s Sharon Lewin on pivoting from chasing COVID zero


The Conversation


Michelle Grattan, Professorial Fellow, University of Canberra

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How will Delta evolve? Here’s what the theory tells us


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Hamish McCallum, Griffith UniversityThe COVID-19 pandemic is a dramatic demonstration of evolution in action. Evolutionary theory explains much of what has already happened, predicts what will happen in the future and suggests which management strategies are likely to be the most effective.

For instance, evolution explains why the Delta variant spreads faster than the original Wuhan strain. It explains what we might see with future variants. And it suggests how we might step up public health measures to respond.

But Delta is not the end of the story for SARS-CoV-2, the virus that causes COVID-19. Here’s what evolutionary theory tells us happens next.




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Remind me again, how do viruses evolve?

Evolution is a result of random mutations (or errors) in the viral genome when it replicates. A few of these random mutations will be good for the virus, conferring some advantage. Copies of these advantageous genes are more likely to survive into the next generation, via the process of natural selection.

New viral strains can also develop via recombination, when viruses acquire genes from other viruses or even from their hosts.




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Explainer: Theory of evolution


Generally speaking, we can expect evolution to favour virus strains that result in a steeper epidemic curve, producing more cases more quickly, leading to two predictions.

First, the virus should become more transmissible. One infected person will be likely to infect more people; future versions of the virus will have a higher reproductive or R number.

Second, we can also expect evolution will shorten the time it takes between someone becoming infected and infecting others (a shorter “serial interval”).

Both these predicted changes are clearly good news for the virus, but not for its host.

Aha, so that explains Delta

This theory explains why Delta is now sweeping the world and replacing the original Wuhan strain.

The original Wuhan strain had an R value of 2-3 but Delta’s R value is about 5-6 (some researchers say this figure is even higher). So someone infected with Delta is likely to infect at least twice as many people as the original Wuhan strain.

Delta variant coronavirus
The Delta variant is an example of how quickly the virus can evolve.
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There’s also evidence Delta has a much shorter serial interval compared with the original Wuhan strain.

This may be related to a higher viral load (more copies of the virus) in someone infected with Delta compared with earlier strains. This may allow Delta to transmit sooner after infection.

A higher viral load may also make Delta transmit more easily in the open air and after “fleeting contact”.




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Why is Delta such a worry? It’s more infectious, probably causes more severe disease, and challenges our vaccines


Do vaccines affect how the virus evolves?

We know COVID-19 vaccines designed to protect against the original Wuhan strain work against Delta but are less effective. Evolutionary theory predicts this; viral variants that can evade vaccines have an evolutionary advantage.

So we can expect an arms race between vaccine developers and the virus, with vaccines trying to play catch up with viral evolution. This is why we’re likely to see us having regular booster shots, designed to overcome these new variants, just like we see with flu booster shots.

COVID-19 vaccines reduce your chance of transmitting the virus to others, but they don’t totally block transmission. And evolutionary theory gives us a cautionary tale.

There’s a trade-off between transmissibility and how sick a person gets (virulence) with most disease-causing microorganisms. This is because you need a certain viral load to be able to transmit.

If vaccines are not 100% effective in blocking transmission, we can expect a shift in the trade-off towards higher virulence. In other words, a side-effect of the virus being able to transmit from vaccinated people is, over time, the theory predicts it will become more harmful to unvaccinated people.

How about future variants?

In the short term, it’s highly likely evolution will continue to “fine tune” the virus:

  • its R value will continue to increase (more people will be infected in one generation)
  • the serial interval will decrease (people will become infectious sooner)
  • variants will make vaccines less effective (vaccine evasion).

But we don’t know how far these changes might go and how fast this might happen.

Some scientists think the virus may already be approaching “peak fitness”. Nevertheless, it may still have some tricks up its sleeve.




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SARS-CoV-2 mutations: why the virus might still have some tricks to pull


The UK government’s Scientific Advisory Group for Emergencies (SAGE) has recently explored scenarios for long-term evolution of the virus.

It says it is almost certain there will be “antigenic drift”, accumulation of small mutations leading to the current vaccines becoming less effective, so boosters with modified vaccines will be essential.

It then says more dramatic changes in the virus (“antigenic shift”), which might occur through recombination with other human coronaviruses, is a “realistic possibility”. This would require more substantial re-engineering of the vaccines.

SAGE also thinks there is a realistic possibility of a “reverse zoonosis”, leading to a virus that may be more pathogenic (harmful) to humans or able to evade existing vaccines. This would be a scenario where SARS-CoV-2 infects animals, before crossing back into humans. We’ve already seen SARS-CoV-2 infect mink, felines and rodents.

Will the virus become more deadly?

Versions of the virus that make their host very sick (are highly virulent) are generally selected against. This is because people would be more likely to die or be isolated, lowering the chance of the virus transmitting to others.

SAGE thinks this process is unlikely to cause the virus to become less virulent in the short term, but this is a realistic possibility in the long-term. Yet SAGE says there is a realistic possibility more virulent strains might develop via recombination (which other coronaviruses are known to do).

So the answer to this critical question is we really don’t know if the virus will become more deadly over time. But we can’t expect the virus to magically become harmless.

Will humans evolve to catch up?

Sadly, the answer is “no”. Humans do not reproduce fast enough, and accumulate enough favourable mutations quickly enough, for us to stay ahead of the virus.

The virus also does not kill most people it infects. And in countries with well-resourced health-care systems, it doesn’t kill many people of reproductive age. So there’s no “selection pressure” for humans to mutate favourably to stay ahead of the virus.




Read more:
We found traces of humanity’s age-old arms race with coronaviruses written in our DNA


What about future pandemics?

Finally, evolutionary theory has a warning about future pandemics.

A gene mutation that allows a virus in an obscure and relatively rare species (such as a bat) to gain access to the most common and widely distributed species of large animal on the planet — humans — will be strongly selected for.

So we can expect future pandemics when animal viruses spill over into humans, just as they have done in the past.




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How do viruses mutate and jump species? And why are ‘spillovers’ becoming more common?


The Conversation


Hamish McCallum, Director, Centre for Planetary Health and Food Security, Griffith University, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Coronavirus Update: Australia


We may need to vaccinate children as young as 5 to reach herd immunity with Delta, our modelling shows


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Emma McBryde, James Cook UniversityRecently released modelling from the Doherty Institute, which the federal government used to back its roadmap out of the pandemic, misses one critical point — the importance of vaccinating children.

The Doherty modelling instead focuses on vaccinating 70-80% of the adult population as thresholds for easing various restrictions, such as lockdowns. It says vaccinating younger adults, in particular, is important to reach these thresholds.

However, our modelling shows vaccinating children is vital if we are to reach herd immunity, which would allow us to ease restrictions and safely open up.

This would mean potentially vaccinating children as young as 5 years old.

However, we are still waiting to see if this is safe and effective, with trials under way in the United States. So we need a plan that assumes we may never achieve herd immunity.

Here’s what our modelling shows and how it differs from the modelling used to advise the federal government.




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Here’s what we did

Our modelling, which we’ve uploaded as a pre-print and has yet to be peer-reviewed, considers different vaccine strategies for Australia to achieve herd immunity. That’s when we can expect no sustained transmission of the virus in the community.

We take into account the Delta variant, which is twice as infectious as the original Wuhan strain of the virus, and has a reproduction number estimated between 5 and 10. In other words, this is when one person infected with Delta is estimated to infect 5-10 others.




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We also consider different contact patterns across various age groups. This is because some age groups are more mobile and have many contacts. If infected, these people are more likely to infect many others, particularly of similar age, which can lead to reservoirs of transmission.

We combine this information with possible vaccine effects. These include the possibility of having the vaccine then becoming infected, having symptoms, and if infected, how serious the illness is and how infectious people are.

This allows us to model what’s likely, given we’re focused on the Delta variant for now, and allows us to assess the impact of strategies across different age groups, types of vaccines and percentage vaccinated.

Our interactive tool also allows rapid response to changing information, such as new variants, or new evidence about vaccine impact.

Delta is more infectious

The Wuhan strain had a basic reproduction number of 2.5. This means, at the start of the pandemic, one person infected with it was expected to infect 2.5 others.

If the Delta variant is twice as infectious, this means its basic reproduction number may be over 5 (at the lower range of international estimates). So this changes the number (and type) of people we need to vaccinate to reach herd immunity considerably.

The simplest form of the herd immunity equation would suggest we needed to fully immunise 60% of the population to achieve herd immunity for the Wuhan strain but as much as 80% for the Delta variant.

If we take into account how different age groups mingle or are in contact with others, the situation is worse.




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For the Wuhan strain, children were not as infectious or susceptible to infection and we predict that if we vaccinate 65% of the adults, transmission would not continue among children.

However, with the Delta variant, we predict children will continue to infect other children, even when most adults are vaccinated.

We also know both the AstraZeneca and Pfizer vaccines are less able to protect against the Delta variant, with a reduced efficacy after one dose and slightly reduced efficacy after two doses.

All this makes achieving herd immunity a great challenge.




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When will we reach herd immunity? Here are 3 reasons that’s a hard question to answer


We estimate if the reproduction number is 5, then vaccinating 85% of the population, including children down to age 5, will be necessary to achieve herd immunity.

If the reproduction number is as low as 3, then vaccinating children will not be necessary to achieve herd immunity and we will only need to vaccinate 60% of the population.

The Doherty modelling uses an effective reproduction number of 3.6. This explains why its modelling does not see vaccinating children as critical to reaching herd immunity. This is the major difference between our model and theirs.

What happens next?

Of course, new variants may arise pushing Delta aside, and the world post-COVID is unpredictable.

The lesson from Delta is if we don’t vaccinate children, we may need to continue some form of public health action to prevent large-scale circulation of the virus.

This would not require stringent lockdown, but may require ongoing mask use and physical distancing, including in children. The alternative is to reduce the focus on case numbers, expect transmission and focus on protecting the most vulnerable.




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Do we need to reach herd immunity?

Herd immunity is not the only possible target. Even if we don’t reach full herd immunity, we may achieve “herd protection”. This provides some reduced risk to people who can’t or won’t be vaccinated, and it will make outbreaks smaller and easier to control.

And without full herd immunity, individuals still benefit from vaccination as they are dramatically less likely to die from COVID.




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How well do COVID vaccines work in the real world?


Do we need to change our vaccination strategy?

We predict Australia’s strategy of vaccinating the elderly and vulnerable first is the best strategy for reducing deaths under most circumstances, particularly when there is insufficient vaccine available.

But once the most vulnerable groups have been covered, we should turn our attention to the highest transmitters to achieve herd protection. In Australia, this group is the late teens and young adults.

Whether we next focus on vaccinating children is controversial and many people have voiced their concerns about going down this path. This is because COVID is generally a very mild illness for most children — although long COVID and life-threatening complications can arise.

So we need to balance the risks with benefits. But included in the benefits should be the potential benefit of herd protection and the freedoms that may bring.




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National Cabinet’s plan out of COVID aims too low on vaccinations and leaves crucial questions unanswered


The Conversation


Emma McBryde, Professor of Infectious Disease and Epidemiology, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.