EXPERT REACTION: Coronavirus - your questions answered

• What are the considerations about development of herd immunity? Is it actually better to have young people (who are at less risk of dying/serious illness) to get COVID-19 to develop herd immunity?

"Herd immunity occurs when the number of people immune to infection in a population is sufficiently large to prevent infection of the non-immune people. For example, let’s say we have a disease for which an individual introduced into an entirely susceptible population infects two new people during their entire infectious period. Assuming recovery from infection leads to immunity, then the number of immune people in the population steadily grows. As the epidemic progresses, more of an individual’s contacts will be immune, making it harder to pass the infection on to new people. When an infected individual is only able to, on average, infect less than one individual the epidemic will die out. This occurs because as an infectious individual recovers, since they infected less than one other person, there will be fewer infectious individuals remaining. So herd immunity (often generated by vaccination, rather than infection) can lead to a disease dying out.

While the evidence seems to be supporting limited COVID-19 disease in young people, there is much uncertainty around the role that young people are playing in transmission. Young people generally have a higher number of contacts than other age groups, and so even if they were less infectious than other age groups due to fewer symptoms (but infectious to some extent), they could still spread infection. In addition, there is too little information at this stage to know whether COVID-19 produces immunity and how long that immunity might last. Herd immunity is more difficult to achieve when immunity is short-lived."

• Why is the UK pursuing herd immunity and should we be doing that here?

"Transmission of infectious diseases is different in different settings, and every government will put their own measures in place based on their priorities and the information that they have available. Rather than speculating on why the UK has introduced the measures they have introduced, I’d encourage interested parties to refer directly to the Public Health England government website (https://www.gov.uk/government/topical-events/coronavirus-covid-19-uk-government-response) for a full understanding of the measures that have been put in place."

• Is Australia heading for the same situation as Italy? What's the modelling?

"Different measures have been introduced, such as banning mass gatherings, requiring returned travellers to self-isolate and providing information for individuals on how to best protect themselves from infection in order to slow the spread of infection in the Australian population and manage the effect on our health care system (see answers to next two questions).  Modelling provides a useful framework to consider the impact of a range of interventions, particularly in the early stages of an epidemic when information is limited, as it allows the uncertainties associated with each approach to be quantified. Modelling is helping Australian states prepare for the likely demand for different health care channels, under a number of possible interventions. As the epidemic progresses, and more information is known about COVID-19, estimates can be refined."

• What is flattening the curve and why is it important? 

"Flattening the curve means slowing the spread of disease down so that the demand on healthcare channels is more evenly distributed over time, rather than being experienced as a sharp peak. If we can reduce the number of infections occurring each day, then more of the people who need hospital beds and intensive care beds will be able to access them."

• What is the best ways for individuals to do this / what are the best ways for communities to do this?

"To flatten the curve, individuals need to reduce their risk of infection. One way to do this is to practise good hygiene, including washing hands thoroughly and frequently, not touching faces, and coughing and sneezing into elbows or tissues. Another way of reducing infection is through social distancing, which includes staying at home if unwell, avoiding large non-essential gatherings and minimising physical contact. Individuals and groups should stay up to date with the latest advice for travellers and those with suspected or confirmed infection at https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert"

• Why Australia hasn't moved to general school closures?

"Paradoxically, children at home may have closer contact than they would at a school that implements social distancing measures (e.g. increased desk spacing, eliminating group activities that require closer contact). If at home, children may need to be looked after by grandparents, who are more vulnerable to serious disease. If at some stage Australia does go down the path of school closures, it will be important to ensure that children are in an environment with appropriate social distancing.

• What are the considerations about development of herd immunity?

"Herd immunity is the term generally used to refer to the prevention of the spread of an infectious illness through vaccination (to confer immunity) of a specified proportion of the population. The key issue here is that for disease to spread, an infectious agent needs to find susceptible (non-immune) people to infect. If it can’t, the chain of infection is interrupted and the amount of disease in the population falls. The key benefit of herd immunity is that those who are most vulnerable to severe disease and who cannot get the vaccination are in fact protected by the rest of the community who do get vaccinated.

How many people need to be vaccinated to achieve herd immunity varies from disease to disease, depending on its contagiousness. For example, measles, one of the most infectious diseases known to man, needs approximately 95 per cent of the population to be vaccinated. It has been suggested that we would need about 70 per cent of the population to be immune to COVID-19 to confer herd immunity to the population."

• Is it actually better to have young people (who are at less risk of dying/serious illness) to get COVID-19 to develop herd immunity?

"Sometimes herd immunity can occur in a population when enough people have contracted and recovered from an infection, and therefore developed immunity. This is in fact how epidemics die out naturally; that is, when there are not enough susceptible people to infect. The advantage of developing herd immunity through vaccination is that you can obtain immunity without developing the illness and therefore the possibility of severe consequences. It is a very risky strategy to allow a disease that is known to have severe outcomes to just run its course in a large group of the population in order to develop herd immunity and in theory protect more vulnerable groups. By doing this you are in fact putting many people at risk of severe illness."

• Is Australia heading for the same situation as Italy? What’s the modelling?

"We hope not. This is exactly why we have instated social distancing so early, before we have started to see a large amount of community transmission. The best indicator of what can happen if we don’t act decisively is what has transpired in China, Italy and South Korea. We have looked at what has happened in these countries and trying to learn the lessons to avoid this."

• What is flattening the curve and why is it important?

"By intervening early in an epidemic we are wanting to limit the spread of an infection. This reduces the number of cases that will present at any one time as the epidemic progresses and it also reduces the number of cases at the peak of the epidemic. This changes the shape of the epidemic curve and flattens it out and this is where the term flattening the curve comes from. By flattening out the epidemic curve we are aiming to reduce the load on the health system at any one time to prevent a situation where the sheer number of cases means the health system is overwhelmed."

• What is the best ways for individuals to do this / what are the best ways for communities to do this?

"The best way for us to flatten the curve is to act decisively to prevent the spread of infection. Individuals need to follow the hygiene advice from the government which includes washing hands often, covering up when sneezing and coughing and staying away from other people if unwell. In addition, the social distancing measures that we are seeing now are one of the most effective ways to limit the spread of illness in communities.

• Why Australia hasn't moved to general school closures?

"As with any action, there are unintended consequences. If all children were to be kept away from school there would be consequences for children in missing out on classes and for parents in having to organise care of their children and who may have to take time off work. This includes parents who are healthcare workers and would not be able to go to work at this important time. Thus, the call seems to have been made at this stage of the epidemic in Australia that the amount of community transmission we have does not justify this action, but you can be assured that this decision will be revisited as we see how the epidemic progresses in Australia.

• Are children likely to be major spreaders of this virus, as is the case with flu?

Very possibly.

Children and young people can certainly be infected. Data from South Korea showed that 5% of SARS CoV2+ individuals were aged 10-19 years – this is 5x higher than this age group in China. More concerning tho was the finding that ~30% of SARS CoV2+ individuals in the South Korea cohort were aged 20-29 years (see Picture 1).

We know that mortality for infected individuals in this age range is very low.

i.e. 0-9 years – no known fatalities
10-19 yrs -  death rate 0.2%
20-29 yrs -  death rate 0.2%
(see Picture 2, from https://www.worldometers.info/coronavirus/coronavirus-age-sex-demographics/)

Of the current 448 cases in Australia, 19 have been detected in individuals under 19 years of age ie. <5%. This increases to be ~10% for each increasing decade til it declines for >70 years  (see Picture 3; from https://www.covid19data.com.au/).

Which means there are likely to be many asymptomatic (ie. apparently heathy) young people in the community who are infected with SARS CoV2; they are not infectious but as they are not showing any symptoms they are probably not self-isolating.

• Are people who are infected but not showing symptoms likely to be major spreaders of this virus?

Again, this is a very real possibility. If young people are not self-isolating and are eg. going out to crowded bars or other places to socialise.

• How long after symptom onset are you infectious?

This table indicates the incubation time is 4-14 days (see Picture 4).

A recent study in the New England Journal of Medicine and Nature Medicine studied paediatric cases of COVID19; one finding was that SARS CoV2 was detectable in rectal swabs after they became undetectable in throat swabs ie. 4 weeks vs 2 weeks suggesting viral excretion can occur via the gastrointestinal as well as the respiratory tracts, with this being longer via gastrointestinal secretions.

• How long does COVID-19 survive on surfaces?

One recent study suggested this varies depending on the type of surface ie. less stable on copper surfaces (<8 hours) but persists longer on cardboard and steel (~24 hours) and even longer on plastic (2-3 days).

Immunity/immunology

• Does surviving Covid-19 give you immune protection?

"The answer is that we do not know yet. It seems likely that infection will generate protective immunity, at least in the short-term, and in the absence of virus mutation. There have been rare reported cases of reinfection, where an infected individual seems to have recovered but then tests positive for the virus later, for reasons that are unclear. However, the general consensus amongst experts is that recovery from infection is likely to result in subsequent protection; the reinfection observation is unlikely to have occurred and probably results from a testing regime that gave a false negative result at the time of recovery."
 

• Does one need to experience at least lower respiratory symptoms like bronchitis to mount a protective antibody response needed for immunity? If the virus stays in the nose, would it only illicit a mucosal response and no humoral response?

"It is too early a stage to understand exactly what is happening with the immune response to COVID19 in infected patients. However, based on experience with other infections, it is unlikely that a lower respiratory infection would be required to mount a protective immune response." 
 

• Could this be a factor influencing why kids are under-represented among more severe Covid-19 cases? (are their snotty noses protecting them?)

"One of the most interesting facets of this disease is that kids have been spared the fatal consequences of infection. This should be viewed as one of the few positives associated with the outbreak. The basis for this sparing is not understood, but we do know that children can get infected, can present with fever or remain asymptomatic. In either case, we have a limited knowledge of the degree they can transmit the virus to others."
 

• Can we please have some commentary on herd immunity + the coronavirus? It’s a big issue in the UK

"Herd immunity protects those who cannot mount an immune response or those in whom immunity will not work, usually in the context of a vaccinated population, rather than after natural infection. For some infections, 95% of the population needs to have been vaccinated to provide herd immunity.
 
In the case of COVID19 we have yet to establish what proportion of the population needs to have been infected, and recovered, to cease transmission of the virus amongst the population. However, worst case scenario estimates suggest that over 80% of the population would need to be naturally infected and recovered to cease transmission between people. The key point about herd immunity, which many have interpreted in a different manner here, is that the protected population provide a shield to reduce the transmission of the virus to the vulnerable and those who cannot clear the infection. We experience this in our day to day lives, as it helps protect us from diseases like measles. Using a conservative case fatality rate of 1%, this could result in approximately 500,000 deaths in the UK; this could be reduced if the at risk populations, the elderly and those with comorbidities, were to isolate themselves throughout the pandemic."
 
Biosecurity and Epidemiology

• Should healthy people wear a mask?  

"Respirators, which filter particulates from the air, do have demonstrable protective effects for healthcare workers in the context of respiratory disease such as influenza. Surgical masks also appear to offer some protection. This is important and the potential exposure of healthcare works to infectious agents is much higher than in the general population.
 
In contrast, there are several conflicting studies about the effectiveness of face masks in preventing community acquired infections among the general population.  Many of the studies conducted so far have been on small numbers of individuals that prevent robust evaluation of the data.  However, the general consensus is that the use of masks by non-infected individuals offers limited value in controlling the spread of infection within the community. Indeed, they may give a false sense of security, they may be worn inappropriately, they can promote touching of the face, all of which give rise to a higher risk of infection." 

• What is flattening the curve and why is it important?

"Hospital services have limited numbers of healthcare workers, such as nurses and doctors, limited numbers of beds, a limited number of specialist equipment, such as ventilators. By flattening the curve, it allows healthcare workers and the available infrastructure, time to cope with the number of patients. Modelling indicates that without intervention 50% of cases will occur within 3 weeks of sustained person to person transmission and 95% of cases will occur within 9 weeks."

• What is the current situation like for the healthcare system and will it hold up? 

"This is difficult to comment on as we are research scientists.  However, Australia has a 1st class, well-developed healthcare system and can provide a co-ordinated response.  The system is designed to flex in response to crises and there is no indication that the healthcare system could not cope.  However, the portion of the healthcare system likely to see the greatest pressure will be that with dealing with respiratory care.  There will be additional pressures across the system as healthcare workers contract the disease, resulting in high rates of absenteeism, and as other practitioners are called in to support critical care and units responding to the pandemic."
 

• Why Australia hasn't moved to general school closures? Do epidemiologists agree that children continuing to go to school minimises the risk to vulnerable groups such as the elderly?

"Closing schools works for seasonal flu, because children are susceptible to infection, but it does not necessarily work for all outbreaks. We do not know about coronavirus, which shows a relative sparing of children, in terms of serious disease.  Experience from the Spanish flu did not indicate significant benefits from closing schools. Given the longevity of the incubation period for coronavirus it may only have a marginal impact of flattening the curve. If excluded from school for a 13-week period it is likely that the children would mix anyway, and if carriers transmission would be sustained. The flow on impact to the economy and healthcare system could be significant. The answer is not always “do it now”. Certainly, older citizens and those with underlying comorbidities need to be protected from exposure to the virus, and that protection must last over the peak of cases. Those most at risk, the elderly and those with comorbidities should consider isolating themselves from potential sources of infection, this includes children." 

• Is Australia heading for the same situation as Italy? What's the modelling?

 "Australia is very different to Italy. It is geographically isolated. It is 26 times larger. It has a third of the population. It is difficult to make predictions but given these factors transmission may be slower in Australia, and therefore a flatter peak is possible."

• solutions as well as grim predictions: What works to contain the spread? Any data/research on that would be very valuable.

"Effective handwashing is essential.  The use of soap and proper handwashing for at least 20 seconds is the most effective means of removing virus particles from your hands. In the case of children, supervised hand washing may be appropriate.

Avoid touching the face.  While there is much still to learn about the route of transmission, it is possible that this virus is not only spread through inhalation of viral particles but may enter the body through other soft tissue routes such as the eyes, lips etc.  It is also possible that the virus is shed in faeces and so washing hands after visiting the bathroom is crucial.

Previous experience, such as the 1918 influenza pandemic, have revealed that social-distancing approaches were effective in past pandemics in controlling diseases. The efforts of the Chinese state in implementing and enforcing social distancing have been remarkable in suppressing the number of cases.  They have taken extraordinary steps to protect their populations and to prevent the spread of the virus.  These extreme social distancing measures have worked in the immediate term.  What does social distancing mean? It means not attending mass gatherings, maintaining approximately a distance 2 meters from others when possible, not holding face-2-face meetings, not entering enclosed spaces and avoiding physical contact.

Government interventions, like event closures, play a crucial role, however individual behaviours are even more important. Healthy people should stay 6 feet away from other people whenever possible. They should reduce unnecessary interactions; work from home where possible, have meetings via the internet, avoid physical contact etc. Those that are ill should isolate themselves to protect others, this means staying home, not welcoming visitors into your home, and avoiding sharing household items. That does not mean you cannot enjoy life.  For example, walking in the countryside or playing golf, are activities that are sufficiently distant from others to allow appropriate social distancing.
The caveat for extreme social distancing, as seen in China, is that as soon as the restrictions are lifted there is the potential for a second wave of infections as people who were naïve to the infection suddenly encounter the virus and transmission occurs again.  This may result in apparent higher mortality rates as those who are susceptible stop self-isolating and rejoin the general population."
 
Vaccine development

• Why does it take a long time to build a vaccine?

"Vaccines are the single largest contributor to increased life expectancy in the last century. However, the development of safe and effective vaccines is challenging. An effective vaccine must boost immunity to the infectious agent and must sustain protection over long periods. The vaccine must protect those groups of people most at risk such as the elderly. In addition, the vaccine must not exacerbate the infection by causing immunopathology on exposure to the infecting agent. Finally, the antigens for the vaccine must be capable of being produced in large quantities.
 
Unfortunately, it simply takes time to develop the vaccine, to ensure its safety and efficacy, and to produce sufficient quantities. Arguably, the vaccine we are most familiar with in the seasonal flu vaccine. It is produced in millions of doses every year using a well-established process. Yet, even with the pathways for production, and with safety and efficacy procedures already established, it takes 6 months to produce."

• How would a coronavirus vaccine work?

 "With the emergence of 2019-nCoV, there are now 15 potential vaccine candidates in the pipeline globally using a wide range of technology mRNA, DNA, nanoparticle, synthetic and modified virus-like particles. It will take at least six months for most of these potential vaccines to start phase 1 clinical trials; the vaccines funded by Coalition for Epidemic Preparedness Innovations (CEPI), such as the vaccine being developed by The University of Queensland, are likely to reach trials the quickest. The next challenge will be finding enough production capacity globally to produce these competing vaccines, at a scale that millions or even billions of people can be vaccinated."

• Are there examples of other coronavirus vaccines we can look to/studies showing SARS/MERS safety/efficacy?

"The majority of potential SARS or MERS vaccines have been investigated in cell or animal models and it is difficult to extrapolate results from these models to know if they would be effective in humans. Four potential SARS/MERS vaccines have entered Phase I clinical trials to test for safety. All of these formulations were found to be safe and well tolerated. In short-term experiments the vaccine candidates induced appropriate immune responses in the participants; however in the one long term experiment the ability of the immune response to neutralise the virus waned over time. Due to the genetic relatedness of the viruses, there may be some cross-protection from using a SARS/MERS vaccine while awaiting COVID19 vaccine. However, this would require close monitoring of small groups of vaccinated individuals in areas where there is active transmission of the current virus." 
 
"The emergence of another coronavirus, after SARS-CoV and MERS-CoV suggests these viruses may pose a continuing threat to human beings. This epidemic will eventually peter out, and as history demonstrates, people's memory of the scale and difficulties posed by the current outbreak will gradually blur. However, we must not forget the lessons learned from this crisis.  The lessons learned now will provide a roadmap for the response to future outbreaks. Governments must have the strength to implement drastic measures and rapidly mobilize resources to prevent the spread of the virus and to care for the sick.  However, epidemic preparedness and the ability to rapidly produce new vaccines is a critical step in preventing the next pandemic. Currently, the UK and many Western countries lack a “single source of truth” for disease control, similar to the Centre for Disease Control in the USA. The cost of building and sustaining such an entity to deal with crises such as this, is a tiny fraction of the money the government is now spending to keep the economy afloat, and is an even smaller portion of the monetary impact on the economy as a whole. Government should work to establish a national centre for vaccine development such that we can respond rapidly in the future. This should be done in conjunction with those who have experience in developing vaccines and bringing them successfully to implementation in large populations.

• On anxiety and panic

“The key to reducing unnecessary anxiety, and related social panic, is the provision of transparent, accurate and relevant public information; being delivered by those the public trusts (i.e. real experts, doctors with experience, trusted news sources).

“As well, actually modelling the best behaviour at the highest and most public levels makes a real difference - if we want the public to change behaviour, those with greatest public profile (politicians, health, sports, celebrities) need to show how through their actions.

• Does surviving Covid-19 give you immune protection?

"Infection with COVID19 certainly activates your immune system. Viruses typically do induce immune protection, and this is certainly the case for other types of coronaviruses. At this stage, we (as scientists/immunologists/clinicians) are still in the process of fully characterizing the nature of an immune response that occurs after infection with SARS CoV2. Some studies have found markers in the blood that would indicate virus-induced immune response. Notably, some of these “biomarkers” also associate with increased mortality, indicating hyper-immune activation can be damaging (which is not unique to COVID19). This actually has also indicated a possible means of treating some of the adverse effects of SARS CoV2 infection (ie targeting these biomarkers/inflammatory markers).
 
But whether this immune response will be protective in the long term is unclear." 

• Does one need to experience at least lower respiratory symptoms like bronchitis to mount a protective antibody response needed for immunity?

"No – immunity can be induced in many anatomical sites. “Immune memory” then enables the body to respond to the pathogen during subsequent exposure virtually irrespective of site of entry to the body. Eg immunity induced against tetanus by the tetanus vaccine is probably not to different to that that occurs by treading on a rusty nail." 

• Can we please have some commentary on herd immunity + the coronavirus? It’s a big issue in the UK 

“Herd immunity is something we rely on for a vaccine – not for a naturally occurring virus. This is particularly the case for a virus that is novel, and one that we have limited (but evolving) understanding of its epidemiology, and the strength of the immune response that it induces in infected individuals.
 
Herd immunity is the reliance on, and the ability of, a vaccine to induce successful immunity in a threshold level of the population – such that when natural infection, or epi/pandemic strikes, a large proportion of the population will be immune and thus protected. This will limit the spread of the infection throughout the community.

The threshold level of immunity differs for different viruses. The recent outbreaks of measles infections in various countries is often (and very likely) attributed to reductions in herd immunity, resulting from fewer people being vaccinated. In this case, the threshold for herd immunity against measles has been calculated to be 95 per cent; ie 19 out of 20 people need to be vaccinated in order to prevent unvaccinated people being infected.
 
We do not know what the level of herd immunity that is going to be required to protect the broader community against COVID19. Until this is known and until immunity is elicited more broadly by a vaccine, relying on herd immunity to prevent or slow down this pandemic is not a good strategy.

Immunity/immunology

• Does surviving Covid-19 give you immune protection?

"A recent monkey study out of China where they re-challenged a small number of monkeys two weeks after they recovered from the first infection, showed they were protected from the second infection.

This demonstrates that COVID19 induces at least short term immune protection against re-infection. There are important provisos:

1. Monkeys get a much milder COVID19 infection than most humans with no temperature rise or serious illness - hence we still don't know if this will translate directly to humans.
2. The second challenge was performed just 4 weeks after the primary infection (2 weeks post-recovery) so this still does not tell us whether COVID19 immunity may be long-lived or may wear off several months post-infection.

However, this is the first sign that COVID19 vaccines should be able to prevent COVID19 infection. Clearly, a lot more research is needed but congratulations on this group for advancing our knowledge on immunity acutely post-infection."

• Does one need to experience at least lower respiratory symptoms like bronchitis to mount a protective antibody response needed for immunity?  

"We know from influenza that you don’t need to get lower respiratory tract infection in order to get protective antibody responses – this is because the tonsils and nasopharynx contain a lot of immune cells that are able to recognise and respond to viruses."

•  If the virus stays in the nose, would it only elicit a mucosal response and no humoral response?

 "A mucosal response can comprise a humoral response with production of antibodies, and a cellular response where killer T cells are produced that then can attack virally infected cells. Both of these responses can be triggered by a nasal exposure to virus."

• Could this be a factor influencing why kids are under-represented among more severe Covid-19 cases? (are their snotty noses protecting them?)

"It is likely that children get fewer symptoms from COVID19 infection than adults because they are able to make larger amounts of interferons, molecules made by immune cells that are able to potently suppress virus replication"

• Can we please have some commentary on herd immunity + the coronavirus? It’s a big issue in the UK 

"What the UK is attempting by letting COVID19 run rampant to try and create herd immunity is in my personal view based on a false premise and constitutes a highly unethical experiment on the whole UK population that could have catastrophic consequences.

The motive by the UK is clearly an economic rather than health one as it avoids the need for a country-wide shutdown. The problem is no-one knows how many people in the UK would need to be infected first before we might see development of herd immunity but typically this takes at least 70 per cent of the population to be infected – this would represent at least 50 million people in the UK.

With an estimated case fatality rate of 1-3 per cent, this would involve the deaths of 500 thousand to 1.5 million UK residents. If this were to occur then this experiment should be considered a crime against humanity, and the responsible members of the UK government and their senior advisors should arguably be put on trial. The Chinese have proven that social isolation and contact identification and quarantine policies can dramatically reduce the death toll and the UK and other countries are thereby obliged to follow these proven methods rather than perform unproven experiments with their population's health.

The aim should be to slow down the spread of the virus sufficiently to allow us time to develop an effective vaccine, which is only a matter of time.

Immunity/immunology

• Does surviving Covid-19 give you immune protection?

"There is no evidence that one develops complete immunity against SARS-CoV-2, the virus that causes COVID-19 (the disease). In fact in some patients there seems to be a relapse or re-infection. The situation is fluid and more work need to be done to understand how the virus interacts with its host.
 

• Does one need to experience at least lower respiratory symptoms like bronchitis to mount a protective antibody response needed for immunity?

"Again, there is no strong evidence that a protect response is mounted in humans following exposure to SARS-CoV-2"
 

• If the virus stays in the nose, would it only illicit a mucosal response and no humoral response?

"A recent study conducted by Dr Jincun Zhao at the State Key Laboratory of Respiratory Diseases, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China – published in Immunity in 2020 -  showed that mouse challenged with SARS-CoV, a close relative of SARS-CoV-2  revealed that some immune cells called memory CD4+ T cells in the respiratory tract provided significant protection. However, this needs to be studied in humans."
 

• Could this be a factor influencing why kids are under-represented among more severe Covid-19 cases? (are their snotty noses protecting them?)

"It is well-established that as we get older our immune system gets weaker. For this reason, the elderly are at higher risk of infection than younger persons. As such, the growing but untested dogma is that the weaker immune system of the elderly makes them more vulnerable to SARS-CoV-2. 

Elderly people with pre-existing medical conditions such as those with diabetes and cardiovascular are at particularly higher risk of developing severe COVID-19. A high degree of inflammation is associated with poorer outcome. Finally, there is speculation whether some drugs used to treat heart disease may increase risk of infection. However, this is premature and unsubstantiated by research."
 

• Can we please have some commentary on herd immunity + the coronavirus? It’s a big issue in the UK

"We need to put more focus on finding creative and innovative ways to speed up and implement evidence-based  biomedical strategies to fight this epidemic through rigorous scientific research."

On immunity/immunology

• Can we please have some commentary on herd immunity + the coronavirus? It’s a big issue in the UK

"It (herd immunity) is a risky strategy, but may very well be the ultimate outcome. It's hard to get enough situational awareness to know when things might need to be tightened up, we don't know the duration of immunity after infection, the intensity of transmission in children isn't clear, and it would be hard to prevent mixing between less susceptible and more susceptible groups. Public health interventions are a very blunt tool - it's hard to work out how effective they are, and can't easily be turned on or off."

On Biosecurity / Epidemiology / Social distancing

• Is the 1.5 metres for social distancing accurate? Is there any scientific basis for it?

"The 1.5m level clearly isn't a sharp demarcation (you're not safe at 1.51m and at risk at 1.49m!), and some more recent studies have suggested that most droplets do fall mostly within 1m, so the 1.5 recommendation allows for some uncertainty. Here's a paper that looks at droplet spread with coughing: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0050845"

On immunity/immunology

• Does surviving Covid-19 give you immune protection?

"Yes it does. We are still not entirely clear whether it is full protection however it is much better than no protection."

• Does one need to experience at least lower respiratory symptoms like bronchitis to mount a protective antibody response needed for immunity? If the virus stays in the nose, would it only illicit a mucosal response and no humoral response?

"No that is not the case. Some people with the virus have not discernible symptoms at all, and the body still forms an immune response."

• Could this be a factor influencing why kids are under-represented among more severe Covid-19 cases? (are their snotty noses protecting them?)

"No that is not the case. The reason why children and younger people overall have not been as effected is that they are usual health and well with an immune system that is working as it should. People with comorbidities such as asthma, emphysema, bronchitis, diabetes, heart disease are at higher risk irrespective of age. As we get older, as with everything else, our immune system gets tired as well."

• Can we please have some commentary on herd immunity + the coronavirus? It’s a big issue in the UK

"The Herd Immunity concept works on the principle that if I am vaccinated or already had the virus I am protected from it, but more importantly I cannot give it some else. Furthermore if you have say have 100 people, 1 has the virus and the other 99 people have either been vaccinated or indeed had the virus, there is no where the virus can go -  ie it can’t be transmitted so it eventually dies out. So it comes down to statistics. If 1 person has the virus and the other 99 are not vaccinated or have it, the virus will spread easily. The more people that are vaccinated the better, as it makes it harder for the virus to spread.  So the UK saying let the virus spread and all will be fine, as it will eventually build up a herd immunity. That would be fine if there was no risk to having the virus. However we know that the mortality is ~1-3% which in a population of the size of the UK could mean hundreds of thousands of deaths and millions hospitalised. This is not correct approach to take."

On Biosecurity / Epidemiology / Social distancing

• Should healthy people wear a mask? It's also a big concern from the Chinese communities in Australia, who are angry at the advice from Australia health authorities saying 'ff you are well, you do not need to wear a surgical mask. There is little evidence that widespread use of surgical masks in healthy people prevents transmission in public.'

"The advice from the Australian Department of Health and Chief Medical Officer is correct. As panic buying of masks is stopping supply to the hospitals which really do need them."

• But a study in The Lancet finds wearing masks is effective in a hospital setting during SARS.

"Yes in a hospital setting where you know that the person has the virus."

• Should we be reconsidering the role of masks given that an "absence of evidence of effectiveness should not be equated to evidence of ineffectiveness”?

"We know they are effective on an individual basis if the person in front you has the virus and yes I take the point that no evidence is indeed evidence however from my previous point we don't have the supply chain for everyone to have them and the hospitals need them."

• What is flattening the curve and why is it important?

"The flattening of the curve is in relation to the number of people who have the virus. Basically we are trying to stop the increase, or rise, in the number of new cases so if you imagine the curve of number of cases versus time, if there are no new cases the curve flattens out. The reason why it is some important is that we are demonstrating that the control measures are working and the virus is not being spread and hopefully eventually dies out."

• What is the best ways for individuals to do this / what are the best ways for communities to do this?

"The best thing to do is the simple things like hand washing and hand sanitising. Social distancing. If you are sick then isolate  - staying at home is perfectly fine. Keep a distance from each other. It is very similar to having a horrible cold. If you have a horrible cold you don't want to give it to anyone and if you know someone with a horrible cold you normally don't want to catch it, so you distance yourself. Don't shake hands or kiss each other etc."

• What is the current situation like for the healthcare system and will it hold up?

At this stage all is OK, however if the virus spreads as it has done in other countries like China and Italy it will put huge pressure on the health care system. This the very thing that we are trying to avoid by placing the country into isolation. It is also bigger than COVID-19 as taking up hospital beds with COVID-19 is displacing people with the usual things people go to hospital for. Plus we are about to enter influenza season which 300,000 people had in Australia and which killed ~800 people.

• Why Australia hasn't moved to general school closures?  Do epidemiologists agree that children continuing to go to school minimises the risk to vulnerable groups such as the elderly?

"This is an interesting argument. Understandably we need to protect the most vulnerable which are the elderly and people with comorbities. So increasing their exposure is not a great idea. So if the government does close schools, which on one level makes sense, then children need to be looked after by a low risk group."

• Is Australia heading for the same situation as Italy? What's the modelling?

"Hopefully not! And is the very reason the government is correctly following the advice of the CMO and putting into place the current measures. The sooner we do this, the quicker we can stop the spread of the virus. We know from countries such as Singapore etc that have putting in isolation measures they have effectively stopped the increase in cases. Countries that didn’t do this such as Italy etc have struggled to contain the virus."

• solutions as well as grim predictions: What works to contain the spread? Any data/research on that would be very valuable.

"The basic stuff. Hand washing, hand washing and hand washing! Social isolation."

On vaccine development

• Why does it take a long time to build a vaccine?

"A vaccine is like a medicine. First it needs to be developed. For any medicine to be sold it needs to go through the standard process of clinical trials including phase 1 - 3 trials. We need to insure that the medicine is safe, will not do harm, and know how effective it is."

• How would a coronavirus vaccine work?

"Same is an influenza vaccine."

• How would a coronavirus vaccine be deployed?

"Same as the influenza vaccine."

• Are there examples of other coronavirus vaccines we can look to/studies showing SARS/MERS safety/efficacy?

"Yes they do help point us in the right direction."

On limiting panic:

"As Australia experiences the implications of the coronavirus crisis, the issue is not just a health or economic concern, but also a mental health and wellbeing crisis.
Beyond medical and public health interventions that the government is developing to combat COVID-19, it is necessary to start developing wellbeing, mental health and resilience supports for individuals and communities – including a simple 6-step strategy called STREAM that individuals can put into effect.

If wellbeing and resilience interventions are rolled out early, we prevent people turning up unnecessarily to medical services, and becoming too anxious, developing mental health problems or exacerbating any existing problems such as OCD, anxiety or trauma conditions.

South Australia is at the forefront of pre-emptive and preventative wellbeing interventions that can mitigate the development of mental health dysfunction and improve community outcomes. Therefore, existing resources can easily be upscaled and adapted for the current situation, to help people if they’re stuck at home or are beginning to feel stressed.

Flinders University’s Órama Institute of Mental Health, Wellbeing and Euroscience and SAHMI’s Wellbeing and Resilience Centre have been working to develop more effective wellbeing interventions and can easily provide upscaleable adaptations to counter the challenges of the COVID-19 crisis.

STREAM is the acronym for 6 simple strategies we can all follow if we are quarantined or working from home.

1. S is for Social networking. Social distancing or quarantining may be necessary for our general health, but it doesn’t mean we should cease all social networking. Remain in touch with people through social media or a simple phone call. Share your experiences to facilitate support, or use the best of Australian humour to lighten the situation. Dinners or dessert and coffee over Skype are always a hoot!
2. T is for Time Out. Remember to separate from each other when you’re stuck in the home for long periods. It can be particularly useful to timetable periods of Time Out to minimise the ongoing stress of being in a limited space with others for long periods.
3. R is for Relaxation, mindfulness or yoga strategies. Managing anxiety can be helped through using a variety of relaxation strategies. Breathing and muscular relation exercises, mindfulness training, dancing, yoga and playing musical instruments are a few available strategies that are effective.
4. E is for Exercise and Entertainment. Burn off some energy if you have a yard or a space where you can get some exercise. Find opportunities in the home to undertake some exercise. Alternatively, entertain yourself by catching up on some reading, streaming services, digital or board games, hobbies, or playing music.
5. A is for Alternative thinking. Uncertainty and novelty will lead to heightened tension and stress. Question yourself if you’re becoming angry (such as supermarket or car rage). Are your fears likely to eventuate? What does science tell us about the most likely outcomes? Is your response reasonable? Are there better ways to manage your underlying motivations? Think things through to find resolution, or talk to someone else, such as a friend or a counsellor.
6. M is for being Mindful of others. Remember, this is just a short-term situation that we can all get through if we work together. Resolving crisis is not new to Australians. We’ve done it before, working together and maintaining courteous and caring interpersonal relationships. Neighbours help each other and no one gets left behind after fires, floods and other times of need. Make sure it happens now. Check on your neighbours, making sure you maintain good hygiene practices. The elderly and those with previous medical conditions are particularly vulnerable and may need support. Never forget that simple acts of kindness make us feel good about ourselves, the world and the future.

Much of what we experience is based on more than objective experiences. It’s also our perception of what happens, our attitudes or beliefs, and how we regulate our emotions.

It’s no different in the current COVID-19 crisis. Many people appear to be controlling their fears and their need for certainty or control through panic buying – but the resulting pandemonium will not see us in good stead in the long run. Panic buying not only leads to many people in need missing out, but also builds further panic.

Numerous irrational behaviours that we currently see will not quell fears or increase our sense of control over perceived uncertainties. Compulsive hoarding of toilet paper, in response to COVID-19, not only doesn’t make sense but is indicative of the mental health challenges we will see at the population level if we don’t take additional actions."