Why some people don’t want to take a COVID-19 test


Jane Williams, University of Sydney and Bridget Haire, UNSW

Last week, outgoing chief medical officer Brendan Murphy announced all returned travellers would be tested for COVID-19 before and after quarantine.

Some were surprised testing was not already required. Others were outraged some 30% of returned travellers in hotel quarantine in Victoria had declined to be tested.

This week, Victorian premier Daniel Andrews said more than 900 people in two Melbourne “hotspots” had declined door-to-door testing.

Again, there was outrage. People refusing COVID-19 tests were labelled selfish and rude.

A positive test result, together with contact tracing, gives public health authorities important information about the spread of SARS-CoV-2, the coronavirus that causes COVID-19, in a community.

So why might people at higher risk of a positive result be reluctant testers? And what can we do to improve testing rates?

The many reasons why

Reluctance to be tested for COVID-19 is not unique to returned travellers in hotel quarantine or people living in “hotspot” suburbs.

In the week ending June 28, FluTracking, a voluntary online surveillance system, reported only 46% of people with a fever and cough had gone for a COVID-19 test.

That can be for a variety of reasons.

A medical test result is not a neutral piece of information. People may refuse medical testing (if they have symptoms) or screening (if no symptoms) of any type because they want to avoid the consequences of a positive result.

Alternatively, they might want to avoid the perceived burden of the test procedure itself.

Reasons may relate to potentially losing money or work

Many reasons for avoiding testing are likely to be structural: a casualised workforce means fewer workers with sick leave and a higher burden associated with having to isolate while waiting for test results. After a COVID-19 test in NSW, for instance, this can take 24-72 hours.

Then there’s the issue of precarious work. If people can’t attend work, either waiting at home for test results or recovering from sickness, they may lose their job altogether.




Read more:
If we want workers to stay home when sick, we need paid leave for casuals


In the case of hotel quarantine, a positive result on day ten will mean a longer stay in isolation. Hotel quarantine is not an easy experience for many, particularly if quarantining alone.

An extension of time at a point where the end is in sight may be a very difficult proposition to stomach, such that avoiding testing is a preferable option.

Another structural issue is whether governments have done enough to reach linguistically diverse communities with public health advice, which Victoria’s chief health officer Brett Sutton recently admitted may be an issue.

Through no fault of their own, may people who don’t speak English as a first language, in Victoria or elsewhere, may not be getting COVID-19 health advice about symptoms, isolation or testing many of us take for granted.




Read more:
Multilingual Australia is missing out on vital COVID-19 information. No wonder local councils and businesses are stepping in


People might fear the procedure or live with past traumas

Reasons may be personal and include fear of the test procedure itself (or fear it will hurt their children), distrust in government or public health systems, and worry about the extent of public health department scrutiny a positive result will bring.

People may also feel unprepared and cautious in the case of door-knocking testing campaigns.

We can’t dismiss these concerns as paranoid. Fears of invasive procedures are associated with past trauma, such as sexual abuse.

People who have experienced discrimination and marginalisation may also be less likely to trust governments and health systems.

COVID-19 can also lead to social stigma, including blame and ostracism, even after recovery.

As with any health-related decision, people usually consider, consciously or not, whether benefits outweigh harms. If the benefit of a test is assumed to be low, particularly if symptoms are light or absent, the balance may tip to harms related to discomfort, lost income or diminished freedoms.

Should we force people to get tested?

Although federal and state laws can compel certain people to undergo testing under limited circumstances, acting chief medical officer Paul Kelly said it was “a last resort”.

Forcing a person to undergo a test contravenes that person’s right to bodily integrity. This is the right to make decisions about what happens to your own body, without outside coercion.

It also involves medical personnel having to override their professional responsibility to obtain voluntary and informed consent.

Some states have indicated they will introduce punishments for refusing testing. They include an extension of hotel quarantine and the potential for fines for people not willing to participate in community testing.




Read more:
Lockdown returns: how far can coronavirus measures go before they infringe on human rights?


Forced testing will backfire

We don’t think forced testing is the way to go. A heavy-handed approach can create an antagonistic and mistrustful relationship with public health institutions.

The current situation is not the only infectious disease emergency we will face. Removing barriers to participating in public health activities, in the immediate and long term, will enable people to comply with and help build trusted institutions. This is likely to create an enduring public good.

Victoria is trying to make testing easier. It is offering a test that takes a saliva sample rather than a nasal swab, which is widely perceived to be unpleasant.




Read more:
Explainer: what’s the new coronavirus saliva test, and how does it work?


This may encourage parents to have their children tested. The test is less sensitive, however, so the gains in increased uptake may be lost in a larger number of false negatives (people who have the virus but test negative).

Ultimately, we need to understand why people refuse testing, and to refine public health approaches to testing that support individuals to make decisions in the public interest.The Conversation

Jane Williams, Researcher at the Centre for Values, Ethics and the Law in Medicine (VELiM), University of Sydney and Bridget Haire, Postdoctoral Research Fellow, Kirby Institute, UNSW

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

The vaccine we’re testing in Australia is based on a flu shot. Here’s how it could work against coronavirus



Shutterstock

Kylie Quinn, RMIT University and Kirsty Wilson, RMIT University

A new trial has begun in Victoria this week to evaluate a potential vaccine against COVID-19.

The vaccine is called NVX-CoV2373 and is from a US biotech company, Novavax.

The trial will be carried out across Melbourne and Brisbane, and is the first human trial of a vaccine specifically for COVID-19 to take place in Australia.

This vaccine is actually based on a vaccine that was already in development for influenza. But how might it work against SARS-CoV-2, the coronavirus that causes COVID-19?




Read more:
Could BCG, a 100-year-old vaccine for tuberculosis, protect against coronavirus?


What’s in the mix?

Vaccines trigger an immune response by introducing the cells of our immune system to a virus in a safe way, without any exposure to the pathogen itself.

All vaccines have to do two things. The first is make our immune cells bind to and “eat up” the vaccine. The second is to activate these immune cells so they’re prepared to fight the current and any subsequent threats from the virus in question.

We often add molecules called adjuvants to vaccines to deliver a danger signal to the immune system, activate immune cells and trigger a strong immune response.




Read more:
Revealed: the protein ‘spike’ that lets the 2019-nCoV coronavirus pierce and invade human cells


The Novavax vaccine is what we call a “subunit” vaccine because, instead of delivering the whole virus, it delivers only part of it. The element of SARS-CoV-2 in this vaccine is the spike protein, which is found on the surface of the virus.

By targeting a particular protein, a subunit vaccine is a great way to focus the immune response.

However, protein by itself is not very good at binding to and activating the cells of our immune system. Proteins are generally soluble, which doesn’t appeal to immune cells. They like something they can chew on.

So instead of soluble protein, Novavax has assembled the SARS-CoV-2 spike protein into very small particles, called nanoparticles. To immune cells, these nanoparticles look like little viruses, so immune cells can bind to these pre-packaged chunks of protein, rapidly engulfing them and becoming activated.

The Novavax vaccine also contains an adjuvant called Matrix-M. While the nanoparticles deliver a modest danger signal, Matrix-M can be added to deliver a much stronger danger signal and really wake up the immune system.

The spike protein is formed into nanoparticles to attract immune cells, and Matrix-M is added as an adjuvant to further activate immune cells.
Author provided

Rethinking an influenza vaccine

The Novavax vaccine for SARS-CoV-2 is based on a vaccine the company was already developing for influenza, called NanoFlu.

The NanoFlu vaccine contains similar parts – nanoparticles with the Matrix-M adjuvant. But it uses a different protein in the nanoparticle (hemagglutinin, which is on the outside of the influenza virus).

In October last year, Novavax started testing NanoFlu in a phase III clinical trial, the last level of clinical testing before a vaccine can be licensed. This trial had 2,650 volunteers and researchers were comparing whether NanoFlu performed as well as Fluzone, a standard influenza vaccine.




Read more:
Where are we at with developing a vaccine for coronavirus?


An important feature of this trial is participants were over the age of 65. Older people tend to have poorer responses to vaccines, because immune cells become more difficult to activate as we age.

This trial is ongoing, with volunteers to be followed until the end of the year. However, early results suggest NanoFlu can generate significantly higher levels of antibodies than Fluzone – even given the older people in the trial.

Antibodies are small proteins made by our immune cells which bind strongly to viruses and can stop them from infecting cells in the nose and lungs. So increased antibodies with NanoFlu should result in lower rates of infection with influenza.

These results were similar to those released after the phase I trial of NanoFlu, and suggest NanoFlu would be the superior vaccine for influenza.

So the big question is – will the same strategy work for SARS-CoV-2?

The Novavax vaccine is one of several potential COVID-19 vaccines being trialled around the world.
Shutterstock

The Australian clinical trial

The new phase I/II trial will enrol around 131 healthy volunteers aged between 18 and 59 to assess the vaccine’s safety and measure how it affects the body’s immune response.

Some volunteers will not receive the vaccine, as a placebo control. The rest will receive the vaccine, in a few different forms.

The trial will test two doses of protein nanoparticles – a low (5 microgram) or a high (25 microgram) dose. Both doses will be delivered with Matrix-M adjuvant but the higher dose will also be tested without Matrix-M.

All groups will receive two shots of the vaccine 21 days apart, except one group that will just get one shot.

This design enables researchers to ask four important questions:

  1. can the vaccine induce an immune response?

  2. if so, what dose of nanoparticle is best?

  3. do you need adjuvant or are nanoparticles enough?

  4. do you need two shots or is one enough?




Read more:
Coronavirus anti-vaxxers aren’t a huge threat yet. How do we keep it that way?


While it’s not yet clear how the vaccine will perform for SARS-CoV-2, Novavax has reported it generated strong immune responses in animals.

And we know NanoFlu performed well and had a good safety profile for influenza. NanoFlu also seemed to work well in older adults, which would be essential for a vaccine for COVID-19.

We eagerly await the first set of results, expected in a couple of months – an impressive turnaround time for a clinical trial. If this initial study is successful, the phase II portion of the trial will begin, with more participants.

The Novavax vaccine joins at least nine other vaccine candidates for SARS-CoV-2 currently in clinical testing around the world.The Conversation

Kylie Quinn, Vice-Chancellor’s Research Fellow, School of Health and Biomedical Sciences, RMIT University and Kirsty Wilson, Postdoctoral Research Fellow, RMIT University

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

Keep your nose out of it: why saliva tests could offer a better alternative to nasal COVID-19 swabs



Shutterstock

Pingping Han, The University of Queensland

Saliva is one of our biggest foes in the COVID-19 pandemic, because of its role in spreading the virus. But it could be our friend too, because it potentially offers a way to diagnose the disease without using invasive nasal swabs.

Our research review, published in the journal Diagnostics, suggests saliva could offer a readily accessible diagnostic tool for detecting the presence of SARS-CoV-2, the virus that causes COVID-19, and might even be able to reveal whether someone’s immune system has already encountered it.

COVID-19 testing is a crucial part of the pandemic response, especially now countries are gradually lifting social distancing restrictions. This requires widespread, early, accurate and sensitive diagnosis of infected people, both with and without symptoms.

Our review looked at the results of three different studies, in Hong Kong, the nearby Chinese mainland city of Shenzhen, and Italy. All three studies found SARS-CoV-2 is indeed present in the saliva of COVID-19 patients (at rates of 87%, 91.6%, and 100% of patients, respectively). This suggests saliva is a potentially very useful source of specimens for detecting the virus.




Read more:
The positives and negatives of mass testing for coronavirus


Saliva spreads the SARS-CoV-2 virus via breathing, coughing, sneezing, and conversation, which is why guidelines suggest we maintain a distance of at least 1.5 metres from one another. We also know SARS-CoV-2 can survive in tiny droplets of saliva in an experimental setting.


Author provided

Saliva is an attractive option for detecting SARS-CoV-2, compared with the current tests which involve taking swabs of mucus from the upper respiratory tract. Saliva is easy to access, which potentially makes the tests cheaper and less invasive. Saliva can hold up a mirror to our health, not just of our mouth but our whole body.

For this reason, saliva has already been widely investigated as a diagnostic tool for chronic systemic diseases, as well as for oral ailments such as periodontal disease and oral cancers. But less attention has been given to its potential usefulness in acute infectious diseases such as COVID-19, perhaps because researchers and clinicians don’t yet appreciate its full potential.

What a mouthful

When we get sick, much of the evidence is present in our saliva – from the germs themselves, to the antibodies and immune system proteins we use to fight them off. Saliva also contains genetic material and other cellular components of pathogens after we have broken them down (for the full biochemical breakdown of the weird and wonderful things in our saliva, see pages 51-61 of our review).


Author provided

Saliva is also hardy. It can be stored at –80℃ for several years with little degradation.

This means it would be relatively straightforward to track the progression of COVID-19 in individual patients, by collecting saliva at various times during the disease and recovery. Saliva tests from recovered patients could also tell us if they have encountered the disease for a second time, and how strong their immune response is.

However, there is no research yet available on using saliva to monitor immune responses. This will be well worth investigating, given the pressing need for a reliable and cost-effective way to monitor the population for immunity to COVID-19 as the outbreak continues.

Could saliva testing replace nasal swabs?

An ideal saliva test would be a disposable, off-the-shelf device that could be used at home by individuals, without exposing them or others to the risk of visiting a clinic.

One drawback with the research so far is that it has involved small numbers of patients (each of the three studies we reviewed involved no more than 25 people), and there is little published detail on exactly how these studies collected the saliva – whether from the mouth or throat, whether by spitting, drooling or swabbing, and whether collected by the patient or by a clinician.

Nevertheless, based on the modest amount of research done so far, saliva looks like a promising candidate for COVID-19 testing. More research is now needed, in larger groups of people, to learn more about how to confidently test for SARS-CoV-2 in the saliva of both symptomatic and non-symptomatic people.




Read more:
Curious Kids: why do we make saliva?


Earlier this month the US Food and Drug Administration approved the sale of saliva-based COVID-19 test kits that will allow people to collect their own samples and send them to a lab for analysis.

A reliable test would offer a cheaper, less invasive and potentially even more accurate way to detect the virus, which would also reduce the risk posed by routine COVID-19 checks to both patients and front-line medical professionals.The Conversation

Pingping Han, Postdoctoral Research Fellow, The University of Queensland

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

The positives and negatives of mass testing for coronavirus



Shutterstock

Jennifer MacLachlan, The Peter Doherty Institute for Infection and Immunity and Benjamin Cowie, The Peter Doherty Institute for Infection and Immunity

Many jurisdictions around the world are now testing people without symptoms as part of efforts to manage COVID-19. In Victoria, asymptomatic health-care workers have been part of the recent “testing blitz”.

We tend to take for granted that the results of medical tests are accurate – but no test is perfect and all carry a risk of harm of some kind. Although there has been a drive to increase testing, we must recognise this is also true for coronavirus.




Read more:
What is sentinel surveillance and how might it help in the fight against coronavirus?


All tests have limitations

Among the shortfalls of diagnostic testing is the possibility of false negatives (failing to detect a condition when it’s present) and false positives (detecting a condition when it’s absent).

It’s easy to see why false negatives can be a problem – we lose the benefits of early intervention.

But false positives can also cause harm, including unnecessary treatment. This is why positive screening tests are often followed up with a second, different test to confirm a diagnosis.

Examples include further imaging and possibly biopsy following a positive mammogram for breast cancer, or colonoscopy following positive screening for colon cancer.




Read more:
As restrictions ease, here are 5 crucial ways for Australia to stay safely on top of COVID-19


Why do we get false positives?

False positives can occur for many reasons, including normal human and system errors (for example mislabelling, data entry errors or sample mishandling).

Sometimes false positive test results could be due to a cross-reaction with something else in the sample, such as a different virus.

Data entry errors can lead to false positives or false negatives.
Shutterstock

For COVID-19, the only routinely available option to confirm a positive result is to retest using the same method. This can address the false positives generated through sample contamination or human error.

Even so, some authorities recommend isolation for any person who returns a positive test, regardless of subsequent results.

Testing more widely could mean more false positives

The proportion of false positives among all positive results depends not just on the characteristics of the test, but on how common the condition being tested for is among those being tested.

This is because even a highly specific test – one that generates hardly any false positives – may still generate more false positive results than there are actual cases of the condition in those being tested (true positives).

Let’s work through an example.

Say we have a very good test which is 99.9% specific – that is, only one in 1,000 tests give a false positive. And imagine we’re testing 20,000 people for condition X. Condition X has a very low prevalence – we estimate it affects 0.01%, or one in 10,000 people in the population.

At this level we could expect two people in our sample to have condition X, so we might get two true positive results. But we would also expect around 20 false positive results, given the error rate of our test.

So the proportion of people testing positive who actually have condition X would be only two out of 22, or 9.1%.

This is called the positive predictive value of a test. The lower the prevalence of a condition in the population, the lower the positive predictive value.

What about COVID-19?

In Australia, control measures have been very successful in reducing the number of people currently infected with COVID-19. We estimate the likelihood of a positive test to be very low right now (although of course this may change as restrictions ease).

The current reported number of active COVID-19 cases in Australia is about 600. And even if we’ve only diagnosed one in every ten people currently infected, this still represents less than 0.03% of the population.




Read more:
Can you get the COVID-19 coronavirus twice?


While we’re still establishing the specificity of tests for SARS-CoV-2 (the coronavirus that causes COVID-19), early evidence suggests an estimate of 99% or greater is reasonable.

However, following the same calculations as in the example above, at a prevalence of 0.03%, even a test with 99.9% specificity would mean only 30% of people who test positive actually have the condition. This means more than two-thirds of positive results would actually be false positives if we were testing asymptomatic people with no increased risk.

This is why testing criteria are often applied. If testing is offered only to those with symptoms consistent with COVID-19, the condition is almost certainly more common in those being tested than in the general (asymptomatic) population, and therefore the rate of true positives is going to be higher.

But if we start testing more broadly, the likelihood of false positives becomes a greater concern.

Why are false positives a problem?

Clearly we need tests to be as sensitive as possible – it’s easy to see why a false negative COVID-19 result could be a serious issue. But it’s important to recognise a false positive result can also cause significant problems for an individual and the community.

Consider, for example, the impact of asymptomatic health worker screening if a false positive test result leads to isolation of the person falsely diagnosed, and quarantining of their clinical co-workers identified (incorrectly) as close contacts of a case of COVID-19.

Further, a person who has had a false positive result may feel they are not at risk of future infection as they believe they are immune, leading to potential consequences for the individual and their contacts.

Even from an epidemiologicial perspective, a high proportion of false positives could distort our understanding of the spread of COVID-19 in the community.




Read more:
More testing will give us a better picture of the coronavirus spread and its slowdown


Testing for COVID-19 in Australia is highly regulated and uses the best possible tests and highly qualified staff.

But asymptomatic screening when the prevalence of a condition is as low as that of COVID-19 in Australia currently must carefully weigh the benefits of such testing against the potential harms.The Conversation

Jennifer MacLachlan, Epidemiologist, WHO Collaborating Centre for Viral Hepatitis, The Peter Doherty Institute for Infection and Immunity and Benjamin Cowie, Director, WHO Collaborating Centre for Viral Hepatitis, The Peter Doherty Institute for Infection and Immunity

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

The coronavirus risk Australia is not talking about: testing our unlawful migrant workers



http://www.shutterstock.com

Marie Segrave, Monash University

As Australia starts to emerge from its coronavirus lockdown, authorities are on high alert for any fresh breakouts of the disease.

One of the risks we need to keep an eye on is hard to see: the tens of thousands of unlawful migrants who work here every day without a valid visa.

My research shows Australia’s unlawful migrant workers already face routine exploitation and in some cases, terrible work conditions. But the arrival of COVID-19 presents new and worrying health challenges, for them and the broader Australian population.




Read more:
This is why Singapore’s coronavirus cases are growing: a look inside the dismal living conditions of migrant workers


In recent weeks, Singapore has gone from global poster child for tackling coronavirus, to the home of more than 19,000 cases, after infections took off among its migrant workers.

Singapore’s migrant workers live in purpose-built accommodation and are officially known to the government. In Australia, our unlawful migrant workers live under the radar, so are even harder to identify and support.

Unlawful migrant workers in Australia

There is little data about the precise numbers of people working in Australia illegally. The best estimate is still a 2011 report to the Gillard government suggesting there are between 50,000 and 100,000 non-citizens working here without permission.

This group is different from temporary visa holders, who are also facing their own financial struggles during the lockdown.

Unlawful migrants workers come to Australia on valid visas and then breach their visas conditions. This includes those who overstay their visas and those who come on a visa without work rights.

In my 2017 research across NSW and Victoria, I spoke to such people who worked in industries including domestic labour, agriculture, hospitality and commercial cleaning.

It is estimated that tens of thousands of people work in Australia without a valid visa in industries such as fruit picking.
http://www.shutterstock.com

They described physical and verbal abuse, no or low pay, poor accommodation, withholding of passports and threats of being reported to immigration authorities.

The COVID-19 challenge

The arrival of COVID-19 presents new risks for unlawful workers in Australia.

They face destitution if work disappears and new opportunities fail to arrive. A key concern is that unlawful migrants will accept exploitative working conditions, with little or no pay, and no incentive to come forward for help.

In April, Prime Minister Scott Morrison told visitors to “return to their home countries” if they cannot support themselves in Australia.

However, this is not a solution for unlawful workers: it is not clear how people would leave or how they would pay for their travel. It is also likely many will be compelled to stay.




Read more:
6 countries, 6 curves: how nations that moved fast against COVID-19 avoided disaster


In my research, I spoke with people who had been in the country for a matter of days and people who had been in the country for close to 20 years – undocumented and working. Often they were sending money home to their family in their country of origin, with some setting up new homes and families in Australia.

Leaving is not a straightforward option.

The public health risks

Unlawful workers also present a public health risk for Australia during the COVID-19 pandemic.

Not only do they tend to live in overcrowded accommodation, they also tend to move around frequently, seeking work and better living conditions.

Critically, unlawful migrant workers are also reluctant to access community support – for any reason – due to fears they may be reported to immigration authorities and then detained and deported. My research found this group will actively avoid any contact with formal service providers from police to health care workers.

Unlawful migrant workers are unlikely to access healthcare services, such as COVID-19 testing, for fear of being reported to immigration authorities.
Loren Elliott/ AAP

This reluctance presents a risk to their health and that of the broader community: if an unlawful migrant has COVID-19 symptoms, they are unlikely to access testing or health care.

As Australia starts to ease some lockdown restrictions and boosts testing for any signs of COVID-19, it is critical all relevant people in the community come forward if they have symptoms.

We need to build a ‘firewall’

Before the global pandemic, there has been growing recognition, at national and international levels, of the need for a firewall between protections for migrant workers and immigration processes.




Read more:
Is slowing Australia’s population growth really the best way out of this crisis?


A firewall offers dedicated protection for undocumented workers to come forward – to seek health care, or police or other assistance in the context of workplace exploitation – with the clear understanding that their visa status will not be referred on to immigration authorities.

While my research did not find health services reporting unlawful migrants to the Australian Border Force, the role of a firewall is to ensure there is a formal commitment that this will not happen across any community service.

What we need to do now

In the short term, a formal firewall is unlikely because it would require a shift away from the Morrison government’s strong emphasis on border control.

But national and state leaders could send clear reassurances that we want all people to come forward to seek testing and health care workers will not be asking immigration-related questions.

Singapore has seen an increase in coronavirus cases after outbreaks among its migrant workers.
How Hwee Young/ AAP

This then needs to filter down to localised programs. Proactive efforts to reach undocumented individuals and groups is detailed but necessary work and requires trust between parties.

If this message does not get through, we risk a quiet spread of COVID-19 among untested, unlawful residents, who live in close quarters and are often very mobile – and who are unlikely to come forward until they are very unwell.

Singapore’s situation shows what can happen when groups of migrant workers are not prioritised.The Conversation

Marie Segrave, Associate Professor, Criminology, Monash University

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

What is sentinel surveillance and how might it help in the fight against coronavirus?


Nic Geard, University of Melbourne; Jodie McVernon, University of Melbourne, and Katherine Gibney, The Peter Doherty Institute for Infection and Immunity

By international standards, Australia has had considerable success in containing the COVID-19 outbreak. As the number of new cases continues to decline, several states have announced they will begin to ease restrictions.

But debate about when and how we can ease physical distancing measures safely remains ongoing.

Modifying restrictions too soon, or making too many changes concurrently, could easily see a resurgent second wave of COVID-19.




Read more:
6 countries, 6 curves: how nations that moved fast against COVID-19 avoided disaster


To prevent this, we need to ensure any new infections in the community are detected promptly, and their contacts traced to contain transmission as early as possible.

Sentinel surveillance – or testing randomly in the community – could help us with this.

Testing is key

Testing provides our window onto the extent of infection in a population: where we look determines what we see.

The differences in reported case numbers between different countries can be at least partially attributed to different levels of testing. For example, if testing is restricted only to patients in hospital, less severe cases won’t be counted.

To be confident transmission doesn’t increase as distancing measures are lifted, we will need to test broadly, and strategically, across the population.




Read more:
What might trigger a return to ‘normal’? Why our coronavirus exit strategy is … TBC


So who do we test?

Testing is a finite resource: health services need physical kits to conduct the tests, and laboratories need time and people to analyse samples. So testing efforts are concentrated where they’re most likely to aid control efforts.

The decision to test someone is guided by testing criteria, which in Australia are set at the state and territory level.

Testing will be particularly important as we start to ease restrictions.
Shutterstock

In the early stages of Australia’s outbreak, the greatest risk of infection was among people arriving from overseas. Testing understandably focused on this group, as well as people who had been in contact with confirmed cases.

At that time, and since, Australia has maintained one of the highest rates of testing globally.

As the number of cases imported from overseas fell, attention shifted to transmission occurring in the community. From early April, testing criteria were expanded nationally to include any health-care and aged care workers who developed respiratory symptoms.



The Conversation, CC BY-ND

Where are we now?

Last week, testing criteria were broadened even further. Anybody in Australia experiencing symptoms of respiratory infection can now get a test.

We know COVID-19 can manifest with a broad range of potentially minor symptoms, so this approach should help highlight milder cases of infection.

But even this level of testing might not be enough to provide early warning of and prevent an impending outbreak.




Read more:
More testing will give us a better picture of the coronavirus spread and its slowdown


While we still have more to learn about the virus, there is evidence that infected people may be able to transmit infection to others before they develop symptoms.

This poses a challenge when public health surveillance is based on symptoms. By the time someone realises they’re sick and presents for testing, they may already have been shedding virus and infecting others.

Meanwhile, other people may experience trivial or no symptoms. We don’t know yet whether these people can spread infection.

Physical distancing measures currently limit the number of contacts at risk from potentially infectious people without symptoms. Once we lift these measures the number of people we have contact with will increase.

So identifying infected people with no symptoms is crucial, especially now. We need to consider more active approaches to surveillance.

Enter sentinel surveillance

Sentinel surveillance involves testing people across the community, including those who are apparently well, in order to discover unseen transmission.

Often, sentinel surveillance programs involve a prearranged set of health-care providers. For example, the Victorian Sentinel Practice Influenza Network (VicSPIN) is a general practice-based program that provides information about the proportion of patients with influenza-like illness.

Government and public health agencies are still determining the appropriate design of a sentinel surveillance program for COVID-19 in Australia.

New Zealand recently established sentinel community testing centres to randomly test volunteers with no symptoms of COVID-19.

In the UK, where prevalence is much higher, there have been calls for mass testing of the entire population on a regular basis to help bring the outbreak under control. But such a resource-intensive approach would be challenging to implement.

It’s more likely a sentinel surveillance system in Australia would aim to test a geographically and demographically diverse sample of the population.

Additional emphasis may be placed on groups at higher risk should an outbreak occur, such as those in detention facilities or group residential settings.




Read more:
To get on top of the coronavirus, we also need to test people without symptoms


Sentinel testing could involve, for example, testing every fifth person a particular GP sees on one day, every tenth person leaving a shopping centre on one day, or a selected group of frontline workers without symptoms.

While we don’t yet have a national timeline, sentinel surveillance is likely to form the next step in Australia’s testing regime.

Victoria has already commenced wider scale testing, pledging to test up to 100,000 people over two weeks, including volunteers from vulnerable settings without symptoms.The Conversation

Nic Geard, Senior Lecturer, School of Computing and Information Systems, University of Melbourne; Senior Research Fellow, Doherty Institute for Infection and Immunity, University of Melbourne; Jodie McVernon, Professor and Director of Doherty Epidemiology, University of Melbourne, and Katherine Gibney, NHMRC early career fellow, The Peter Doherty Institute for Infection and Immunity

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

Latest coronavirus modelling suggests Australia on track, detecting most cases – but we must keep going


Trent Yarwood, The University of Queensland

Late yesterday, epidemiologists from the Doherty Institute released what the Chief Medical Officer described as “nowcasting”: modelling that uses data from the previous 14 days to more accurately understand the present state of the COVID-19 epidemic.

In short, the findings are reassuring and suggest the inconvenience of social isolation is helping control the spread of SARS-CoV-2 in Australia.

It also indicates the spectre of “unidentified community transmission” is very unlikely indeed. This should be especially reassuring for healthcare workers, who may worry about coming into contact with COVID-positive patients presenting with a non-COVID problem.

What I don’t think it means, however, is that our outbreak control has been so effective that we should consider loosening the restrictions now.

Overseas methods, Australian data

The important thing to know is that this latest modelling uses Australian data.

One of the earlier criticisms of the Australian government’s response to COVID-19 was that the expert advice was kept behind closed doors.

When the modelling was made public, those determined to find fault (especially on Twitter) pivoted to “But it’s based on overseas data!”

That’s not a criticism that can be levelled at this latest Doherty Institute modelling, which borrows methods developed by the London School of Tropical Medicine and Hygiene but uses really recent Australian data to build some estimates.




Read more:
This isn’t the first global pandemic, and it won’t be the last. Here’s what we’ve learned from 4 others throughout history


We are likely detecting most COVID-19 cases

First, the modelling suggests there’s probably not some huge secret cohort of COVID-19 cases out there that we are not picking up due to insufficient testing.

The researchers compared the reported case-fatality rates (the proportion of COVID-19 positive people who died) in Australian states with that from a large Chinese study (1.38%).

This is then used to infer the proportion of cases with symptoms which have been found by testing.

All states/territories have case detection rates above 80% – meaning that in each state, of all the people who have COVID-19 with symptoms, we are picking up about 80% or more.

If it wasn’t for the recent outbreaks in Tasmania, then all states would be above 90%. And in fact, the overall estimated case detection rate Australia-wide is 93%. Good news!

And as time goes on, the researchers are growing more certain about this conclusion (the technical term for this is the change in the “90% confidence interval” but in plain English that means the scientists are growing more confident these estimates are pretty accurate).

The change in the light blue shaded area means scientists are growing more confident that their estimates are accurate as more Australian data becomes available.
Doherty Institute

An effective R below 1: meaning social distancing is working

What scientists call the effective R is the way the virus spreads in a world where social distancing measures are in place. It refers to the average number of people each COVID-19 positive person is infecting. If it is below one, then it means the social distancing measures are working well.

The next model in the new Doherty Institute paper looks at the effective R ₀ in the six states over time.

The effective R ₀ is under one in all states except Tasmania, but treat the Tasmanian data with caution: they have a small number of cases and a recent uptick, so that could be blowing out the average.
Doherty Institute

In most states, the effective R has always been below one – indicating Australia has been effective at controlling spread since the beginning of the outbreak.

However, the numbers in Tasmania should be interpreted with caution. Their overall case numbers are small and they just had a big cluster, which affected their average disproportionately.

Crucially, the study team calculated the effective R based on cases identified as local transmission, rather than imported cases. That means, in real life, the effective R may be even better than this model estimates (because this estimate doesn’t account for border restrictions and quarantine of travellers).

In other words, this modelling is aiming to look at how effective our domestic control measures are. And the answer is: they’re working pretty well.

Too soon to relax social distancing rules

The social distancing measures take time to have an effect in stopping transmission.

It would also take time to become visible if we back off too early.

See-sawing our control measures would probably be far more disruptive than holding the course for just a little bit longer, and pose a risk of coronavirus rebound.The Conversation

Trent Yarwood, Infectious Diseases Physician, Senior Lecturer, James Cook University and, The University of Queensland

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

More testing will give us a better picture of the coronavirus spread and its slowdown


Haydar Demirhan, RMIT University

Many states are now ramping up the number of tests by relaxing the criteria for who can get tested for COVID-19. This should give us a better idea of whether the spread is easing or getting worse.

We get regular updates about COVID-19 with lots of data, figures and graphs with some interpretations to see if we are flattening the curve on the number of new cases.

But most of these are based on using only the total or the daily number of confirmed new cases.




Read more:
How much has Australia really flattened the curve of coronavirus? Until we keep better records, we don’t know


This does not provide enough information about whether the situation is improving, stabilising or getting worse. That is why we also need to consider the number of people tested daily for COVID-19.

For example, in percentage terms there is no actual difference between getting 20 positive cases out of 1,000 tests one day and 100 positive cases out of 5,000 tests the next. Both lead to the conclusion we have 2% reported infected people of those tested.

If we are only given the number of new cases, getting 100 in a day sounds a lot worse than getting 20. The 2% percentage figure here tells us things are pretty much the same over the two days.

Curves and trends

Take Victoria, if we look at the total number of confirmed cases we see it followed an exponential trend for a while – one that was increasingly rising – and then started to divert on April 3.



The Conversation, CC BY-ND

In the daily number of confirmed cases we see high jumps and large fluctuations going back and forth.



The Conversation, CC BY-ND

When the daily number of applied tests is considered, we can calculate the actual percentage of new cases each day. Now we have a way flatter curve (below) with different fluctuations.



The Conversation, CC BY-ND

The peak is now on March 24 when the number of tests is included. If we just look at the daily count, the highest number of confirmed cases was on March 27. When we look at the percentage, it shows a decrease rather than an increase with more than 2,300 tests.

From the daily new cases data it looks like there is a strongly decreasing trend in the number of confirmed cases between April 2 and 6.

But we do not see the same strong downward movement in the percentage data on the number of tests. Although both figures go down, then up slightly, the percentage trend downward is not as strong as the daily trend.

This is a good example of the discrepancy between the inferences from the raw and percentage data. When we consider the number of tested people, we get a different view on the progress of the pandemic.

More tests needed

In using the number of tests to get a more reliable picture of the situation, there is an important point to consider. That’s were the purple error bars in the graph (above) come in.

They show the margin of error where each percentage estimate swings for the daily number of applied tests, so the actual number could be higher or lower but within those purple bars.

When we have a larger number of applied tests, we get a reduced margin of error, and that gives us a clearer picture of what is happening.




Read more:
Even in a pandemic, continue with routine health care and don’t ignore a medical emergency


Since the peak on March 24 is backed up by only 500 tests, it has the largest margin of error. The figure on March 28 is based on 8,900 tests with a very small amount of error.

To get a more reliable picture of the situation, the number of applied tests has to be expanded, which it is what is happening in some states. This should reduce the margin of error.

Out in the community

After getting some signals of flattening the curve in Victoria and Australia as well, do we see an exponential increase in just the community transmission?

Community transmission is where someone has caught the virus locally, not an infected traveller who’s returned from a cruise or overseas. At the moment they are the minority of cases and authorities would like it to stay that way to contain the spread of the virus.

Again, we need to consider the number of tests to answer this question clearly. The raw numbers of community transmission in Victoria looked like they were increasing exponentially.



The Conversation, CC BY-ND

But the numbers as a percentage of the number tested tell a different story. Although there is some increase in the rate of community transmissions recently, it still shows a way flatter behaviour far from the exponential curve.



The Conversation, CC BY-ND

That is why it is important to understand the impact of the number of tests on the figures displaying the progress of the pandemic. Understanding this relationship could reassure people about new numbers.The Conversation

Haydar Demirhan, Senior Lecturer in Analytics, RMIT University

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

Antibody tests: to get a grip on coronavirus, we need to know who’s already had it


Larisa Labzin, The University of Queensland

With much of society now effectively in lockdown, how will we know when it’s safe to resume something like normality?

It will largely depend on being able to say who is safe from contracting the coronavirus, officially named SARS-CoV-2, which causes the disease called COVID-19, and who still needs to stay out of harm’s way. A blood test to detect who has antibodies against the virus would be a crucial aid.

An antibody test – which would identify those whose immune systems have already encountered the virus, as opposed to current tests that reveal the presence of the virus itself – will be an important part of efforts to track the true extent of the outbreak.

This is because the antibody test will be able to determine whether someone has been infected with virus, even if they haven’t shown symptoms.




Read more:
Coronavirus: how long does it take to get sick? How infectious is it? Will you always have a fever? COVID-19 basics explained


When we get infected with the novel coronavirus (SARS-CoV-2), one of the ways our immune system fights the virus is by making antibodies. These small molecules bind specifically to SARS-CoV-2 (and not other viruses or bacteria), and combat the infection, mainly by preventing the virus from entering our cells.

Even after we’ve cleared a particular virus infection, these antibodies stay in our bloodstream, ready to protect us if we encounter the same virus again. This is the principle behind vaccination.

Because antibodies are specific to a particular virus, that means if we can detect SARS-CoV-2 specific antibodies in someone’s blood, we know that person has already been infected with the coronavirus.

Scientists in the United States and Europe have already developed specific antibody tests for SARS-CoV-2. Laboratory tests show that only antibodies from SARS-CoV-2 patients will bind to SARS-CoV-2 (and not to the 2003 SARS virus, for example). This tells us the test is specific.

Testing times

Antibody tests are different from the current testing kits used at COVID-19 clinics, which reveal the presence of the virus itself (by detecting its genetic material), rather than our antibodies against it.

That is useful for determining whether someone is currently infected, but cannot spot people who have already fought off the virus. In contrast, the antibody tests won’t be able to detect if someone is newly infected with SARS-CoV-2, as it takes our immune system a week or more to make antibodies. So we still need to do the existing tests to accurately diagnose a current infection.

Many companies have developed rapid test kits for detecting anti-SARS-CoV-2 antibodies. The UK is already rolling out 3.5 million antibody tests, while Australia has ordered 1.5 million antibody tests to determine whether patients showing symptoms of fever and cough are infected.

What still needs to be tested is how specific those kits are. It’s vital that these antibody test kits are only able to detect antibodies against SARS-CoV-2, and not other coronaviruses or even viruses of other types. Otherwise, people might think they are protected against SARS-CoV-2 when in fact they aren’t.

Additionally, because the onset of symptoms may appear within 2-14 days after exposure, a person might test negative to the antibody test but actually be infected. So we really still need to use the two tests together to accurately diagnose patients with COVID-19.

A new test developed by NSW Health Pathology will also be able to determine whether the antibodies in the blood are able to kill the virus. These kinds of tests will help clinicians and scientists measure exactly how soon after infection we develop antibodies, what levels are needed to be protective, and how long these antibodies stay in our body.

This will also help scientists track the spread of the virus and know if someone is going to be immune to reinfection with SARS-CoV-2.

Rapid response

These antibody tests have been developed much more rapidly than vaccines, which are still many months away. This is because the antibody tests are done outside the body, using just a small blood sample, perhaps just a pinprick.

In contrast, a vaccine needs to be injected into the body, so it has to be tested for safety as well as effectiveness.

For a vaccine, we first need to understand how the immune response to the virus itself works, because essentially a vaccine is trying to trick the immune system into thinking it’s seen the virus before so it makes protective antibodies. Then, we need to thoroughly test any candidate vaccine to ensure it doesn’t make people ill. This means we probably won’t see any vaccines for at least 12 months.

The new antibody tests will also help guide vaccine development. By measuring antibody levels in infected and recovered patients, we’ll have a much better idea of the levels of protective antibodies a vaccine needs to elicit.




Read more:
Coronavirus vaccine: here are the steps it will need to go through during development


While we wait for a vaccine, the new antibody tests will give scientists, doctors and public health officials much more information about who gets infected, who has already been infected and recovered, and how protected we are against reinfection.

But there is still a long way to go before we can test people’s blood for antibodies against SARS-CoV-2 and confidently say it is safe for people to go back to work or into the community without getting sick.

Ultimately it is up to our community leaders and public health officials to decide when it is safe for us to resume normal life.The Conversation

Larisa Labzin, Research Fellow, Institute for Molecular Bioscience, The University of Queensland

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

Who can get tested for coronavirus?


Hassan Vally, La Trobe University

To control the spread of COVID-19 we need to identify as many people with the virus as possible. If we know who has it, we can isolate them so they can’t infect others and quarantine their close contacts in case they’ve already been infected.

But some experts are concerned we’re not testing enough. Because of restrictions on who can be tested, they argue, we’re only seeing the tip of the iceberg. Beneath the surface, the virus could be spreading much more than we think.




Read more:
To get on top of the coronavirus, we also need to test people without symptoms


The federal government recently expanded its testing guidelines and now allows states and territories to set their own rules for testing. But before we get to what they say, let’s look at the symptoms.

What are the symptoms of COVID-19?

Colds, influenza and COVID-19 are all respiratory illnesses and share many of the same symptoms.

For COVID-19, the most common symptoms are fever and a dry cough. Other symptoms might include fatigue, the production of phlegm, shortness of breath, a sore throat and a headache.

But some people experience no, or mild, symptoms.


The Conversation, CC BY-ND

What is Australia’s testing criteria?

Across Australia, if you develop a respiratory illness, with or without a fever, you can be tested for coronavirus if you:

  • have returned from overseas in the past 14 days or spent time on a cruise ship

  • have been in close contact with a confirmed COVID-19 case in the past 14 days

  • have severe community-acquired pneumonia and there is no clear cause.




Read more:
Coronavirus: how long does it take to get sick? How infectious is it? Will you always have a fever? COVID-19 basics explained


If you have a fever or a respiratory illness, you can be tested (and in some cases, must be tested), if you:

  • work in health care, aged care or other residential care sectors

  • have spent time in a location with elevated levels of community transmission

  • have spent time at a “high-risk” location where there are two or more linked cases of COVID-19. This could be an aged care facility, a remote Aboriginal community, a correctional facility, a boarding school, or a military base with live-in accommodation.

Who else can get tested?

Australians in all states and territories can get tested if they meet the criteria above, but some states have expanded their criteria.

In Western Australia, if you have fever of 38℃ and over and have signs of a respiratory infection, you may be tested.

In New South Wales, GPs have discretion to test anyone who has symptoms of COVID-19. People who identify as Aboriginal in rural and remote communities may also be tested, as can people who live in communities with local transmission.

South Australia has had a cluster of cases among airport baggage handlers. Therefore, anyone who has symptoms of COVID-19 and has been at the airport in the past 14 days, including the carpark or terminal, should also present.

Queensland will offer testing for people who have symptoms consistent with COVID-19 and live in a Aboriginal or Torres Strait Islander communities, as Indigenous Australians are more vulnerable to COVID-19.




Read more:
Coronavirus will devastate Aboriginal communities if we don’t act now


Victoria has introduced random testing at screening centres, testing every fifth person who presents. This should provide a snapshot of the spread of the virus among a broader section of the community.

The ACT, Northern Territory and Tasmania are following the national guidelines and haven’t included any other groups or situations in which someone can be tested.

So what if you think you have COVID-19?

If you think you have symptoms of COVID-19, call your your GP and advise them of your symptoms and other relevant details, such as travel or contact with a known case.

If you don’t have a usual GP or want to discuss your concerns, call the National Coronavirus Helpline on 1800 020 080. You will be given information on where the closest COVID-19 testing clinic is and detailed advice on whether you should be tested.

If you’re asked to come to a COVID-19 clinic, you’ll need to take precautions. These include driving yourself if possible, wearing a mask if you have one, staying at least 1.5 metres from other people and coughing or sneezing into your elbow.The Conversation

Hassan Vally, Associate Professor, La Trobe University

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