Greater social distancing could curb COVID-19 in 13 weeks
"Infected but Feeling Fine: The Unwitting Coronavirus Spreaders "Has Australia's coronavirus response been too slow off the mark? "Childcare centres to stay open for free during coronavirus pandemic, Scott Morrison announces"" "
25 March 2020
New data reveals efficacy of social distancing
A University of Sydney data study from the Faculty of Engineering has revealed that social distancing must be adopted by at least 80 percent of the Australian population to reduce the spread of COVID-19.
If social distancing measures were adopted by at least 80 percent of the Australian population, we could expect to see a control of the spread of the COVID-19 pandemic in just over three months, new research by the University of Sydney has found.
Led by Complex Systems academic and pandemic modelling expert, Professor Mikhail Prokopenko, the study, which used a peer-reviewed method, also revealed that social distancing would be an unproductive measure if adopted by less than 70 percent of the population.
The research found that if 90 percent of the Australian population adopted social distancing, the spread of COVID-19 could be controlled by July 2020, whereas social distancing of less than 70 percent would not suppress the pandemic.
“If we want to control the spread of COVID-19 – rather than letting the disease control us –at least eighty percent of the Australian population must complywith strict social distancing measures for at least four months,” said Professor Mikhail Prokopenko.
“However, if ninety percent of the population complies, then the duration could be as short as thirteen to fourteen weeks – meaning if we began tomorrow we could expect a control of COVID-19 by July,” he said.
“Conversely, if less than seventy percent of the population is adopting social distancing measures, we cannot suppress the spread of the pandemic and any social distancing could be a fruitless effort,” he said.
“There is a clear trade off – stricter measures imposed earlier would reduce how long our lives are impacted by this disease. On the contrary, laxer protocols could mean a longer, more drawn out and ineffective struggle against COVID-19,” he said.
Study suggests tough measures early on
The research also found that for every day the stricter social distancing measures are delayed, society would need to endure several more days under a longer suppression policy.
“There’s good reason for imposing tough measures early on. The longer we delay the peak, the more time our healthcare system has to prepare for it by accessing more resources such as ICU beds, ventilators, antivirals and trained health workers,” said Professor Prokopenko.
The researchers also found that while school closures had the potential to compensate for ten percent of a lack of social distancing compliance, they only delayed the peak of the pandemic by two weeks.
They also found that school closures did not significantly reduce new cases for older adults, but slightly increased the fraction of new cases in children around the peak of the pandemic in Australia.
Fig 1. Strong compliance with social distancing (at 80% and above) effectively controls the disease during the suppression period, while lower levels of compliance (at 70% or less) do not succeed for any duration of the suppression. Credit: Professor Mikhail Prokopenko, University of Sydney
How the modelling worked
The AceMod simulator, a peer-reviewed method created by the Centre for Complex Systems, comprises over twenty-four million software agents, each with attributes of an anonymous individual, such as age, gender, occupation, susceptibility and immunity to diseases. Contact rates within different social contexts, such as households, household clusters, local neighbourhoods, schools, classrooms and workplaces are also built into the program.
The set of generated agents captures average characteristics of the real population and is calibrated to 2016 Australian Census data with respect to key demographic statistics.
The interactions result in transmission of the disease from infectious to susceptible individuals: given the contact and transmission rates, the simulation computes and updates agents’ states over time, starting from initial infections, seeded in international airports around Australia
In this scenario, 80 percent social distancing could either mean – any person in one household could go out once in five days, or, one member per family of five could go out daily, but the other four stay at home all the time.
Disclosure
The study, Modelling transmission and control of the COVID-19 pandemic in Australia, was authored by PhD students Sheryl Chang and Nathan Harding, as well as Dr Cameron Zachreson, Dr Oliver Cliff and Professor Mikhail Prokopenko from the University of Sydney’s Centre for Complex Systems, and Marie Bashir Institute for Infection Diseases and Biosecurity.
CDC Now Recommends Americans Consider Wearing Cloth Face Coverings In Public
April 3, 2020 5:49 PM ET Colin Dwyer
Updated at 6:20 p.m. ET
President Trump said Friday the Centers for Disease Control and Prevention now recommends that people wear cloth or fabric face coverings, which can be made at home, when entering public spaces such as grocery stores and public transit stations.
It is mainly to prevent those people who have the virus — and might not know it — from spreading the infection to others.
The guidelines do not give many details about coverings beyond: "cloth face coverings fashioned from household items or made at home from common materials at low cost can be used as an additional, voluntary public health measure."
Trump emphasized that wearing masks in public is voluntary and said he will not be doing so.
U.S. health authorities had discouraged healthy Americans from wearing facial coverings for weeks, saying they were likely to do more harm than good in the fight against the coronavirus — but now, as researchers have learned more about how the highly contagious virus spreads, officials have changed their recommendations.
U.S. health authorities have long maintained that face masks should be reserved only for medical professionals and patients suffering from COVID-19, the deadly disease caused by the coronavirus. The CDC had based this recommendation on the fact that such coverings offer little protection for wearers, and the need to conserve the country's alarmingly sparse supplies of personal protective equipment.
Still, as the virus spread to every state in the U.S., it has become clear that people can contract and spread the virus without showing symptoms, rendering it difficult — if not impossible — to distinguish healthy from infected individuals without a formal test. So, it may protect other people who come into contact with the unknowing individual.
And the mask need not be professional-grade to offer some benefit. In fact, officials say it probably shouldn't be: The CDC recommends constructing your own cloth mask, so as to help ensure that doctors and nurses can obtain access to medical-grade surgical or N95 masks amid a widespread shortage of supplies.
With this announcement, the U.S. is following the lead of a number of other countries that have been urging — or outright ordering — their residents to don masks in public. The expanding list includes China and South Korea, where officials have even taken the step of distributing masks.
And while the European Centre for Disease Prevention and Control continues to discourage the use of face masks, some European countries, such as Austria and the Czech Republic, have told their residents to cover up their mouths and noses before entering a store.
This week, the mayors of Los Angeles and New York City also urged residents to do the same.
BREAKING Coronavirus spreads through the air as aerosol, 230 scientists write in open letter to World Health Organization
--- "Infected but Feeling Fine: The Unwitting Coronavirus Spreaders [...] There have also been many hints, subtle and not, that the virus can be transmitted via aerosols .. https://www.nytimes.com/2020/03/17/health/coronavirus-surfaces-aerosols.html . Sixty members of a choir in Mount Vernon, Wash., north of Seattle, gathered on March 10 for a practice session for over two and a half hours. None of them felt ill, and they made no contact with one another. But by this weekend, dozens of the members had fallen ill .. https://www.latimes.com/world-nation/story/2020-03-29/coronavirus-choir-outbreak , and two had died. P - Their experience points toward airborne transmission via aerosols, which can travel farther than the large droplets the W.H.O. and the C.D.C. have emphasized. The virus is still most likely to be expelled with a cough or a sneeze, as far as eight meters .. https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/violent-expiratory-events-on-coughing-and-sneezing/475FCFCBD32C7DB6C1E49476DB7A7446 .. (about 26 feet), according to one study. But studies on influenza and other respiratory viruses, including other coronaviruses, have shown that people can release aerosols .. https://www.researchsquare.com/article/rs-16836/v1 .. containing the virus simply by breathing or talking .. https://www.pnas.org/content/115/5/1081 .. — or, presumably, by singing. P - “I think increasing evidence suggests the virus is spread not just through droplets but through aerosols,” Dr. Chowell said. “It would make a lot of sense to encourage at the very least face mask use in enclosed spaces including supermarkets.”" ---
ABC Health & Wellbeing / By health reporter Paige Cockburn
Posted 1 day ago, updated Yesterday at 11:51am
VIDEO - Health experts have urged the WHO to acknowledge aerosol transmission of COVID-19. 4m 34s
The World Health Organization (WHO) has downplayed airborne transmission of COVID-19 since the pandemic began but now more than 200 scientists are making a plea for action, warning people they aren't as protected as they may think.
The WHO's view has so far been that COVID-19 is spread predominantly through large respiratory droplets — the ones that come flying out of our mouths when we cough, sneeze and speak but then quickly fall to the ground.
But now 239 scientists from 32 different countries and many different areas of science (including virology, aerosol physics and epidemiology) have penned an open letter urging the WHO to change their advice.
"We ignore COVID-19 airborne spread indoors at our peril," the scientists say.
If their plea is heard, the ways in which the world attempts to control the virus could change dramatically.
These are the very tiny respiratory particles (of 5 microns or less in diameter) that you emit when you breathe, speak, laugh, sing and so on.
Because these particles are tiny and light, they can remain suspended in the air and then inhaled by someone else, a bit like cigarette smoke.
This is in contrast to larger, heavier respiratory droplets, which fall quickly to the ground.
There is growing evidence that small droplet (airborne) transmission is a significant route of infection indoors.(Supplied: Airborne transmission of SARS-CoV-2 By Lidia Morawska)
Professor Morawska says scientists have demonstrated "beyond any reasonable doubt" that those microdroplets pose a risk beyond 1 to 2 metres, potentially making the 1.5 metre social distancing rule inadequate.
"We are concerned that people may think they are fully protected by following the current recommendations, but in fact, additional airborne precautions are needed to further reduce the spread of the virus," Professor Morawska says.
VIDEO - Professor Lidia Morawska says viruses can potentially last in the air for hours.
What the scientists want
The signatories of the letter have recommended three key ways to mitigate the risk of airborne transmission of COVID-19.
1. Ventilation (maximise clean outdoor air, minimise recirculating air) particularly in public buildings, workplaces, schools, hospitals, and aged care homes
2. Airborne infection controls such as local exhaust, high efficiency air filtration, and germicidal ultraviolet lights
3. Avoid overcrowding, particularly in public transport and public buildings
"These are practical and can be easily implemented and many are not costly," Professor Morawska says.
What does the research say?
The scientists say that airborne transmission appears to be the only "plausible explanation" for several superspreading events.
Of particular importance was a study (yet to be peer reviewed) of a restaurant in Guangzhou, China .. https://www.medrxiv.org/content/10.1101/2020.04.16.20067728v1 , where 10 people from three different families became infected but none of the waiters or 68 other customers did.
Professor Morawska, who was not involved in the study, says the authors observed no evidence of direct or indirect contact between people, but showed how the transmission occurred through the air in a crowded and poorly ventilated space.
In that restaurant, there was no outdoor air supply apart from the brief and infrequent opening of a fire door.
The researchers found a "recirculation envelope" formed over the three families' tables, which were in the direct line of one air conditioning unit. All other tables were being serviced by four other air conditioning units.
The three families were sitting within the blue cloud of aerosols.(Supplied: medRxiv)
The study concluded that aerosol transmission had some role in this outbreak, as some customers who became infected were sitting as far as 4.6 metres apart and we know that even a cough only pushes large droplets around 2 metres away.
Many studies conducted on the spread of MERS and influenza have also proved the risk of aerosol transmission, Professor Morawska said.
For example, 72 per cent of the 54 passengers on a plane in Alaska which had no ventilation for 4.5 hours contracted influenza in 1977.
"There is every reason to expect that SARS-CoV-2 behaves similarly, and that transmission via airborne microdroplets is an important pathway," the open letter says.
-- To keep the COVID-19 outbreak under control we need to keep growth factor below 1.0 Australia's current growth factor is 1.12 May 24 Jul 7 Average 112 cases per day for the past 7 days Highest 1.28 Mar 18th Lowest 0.87 Apr 14th Find out more ? --
It also warns that transmission may occur through fomites (inanimate surfaces or objects) however experts believe that risk is quite low.
[INSERT: Which reminds us, though wiping down surfaces and other objects people may touch is a safeguard that precaution is likely not nearly as important as 'social distancing', and wearing masks in any place covid is likely to present a danger.]
The WHO says aerosol transmission may only occur during aerosol-generating procedures in healthcare settings, for example intubation (inserting a tube through a person's mouth and into their airway) or resuscitation.
The WHO says more research is required to determine the risk of airborne transmission in other environments.
"High quality research including randomised trials in multiple settings are required to address many of the acknowledged research gaps," the WHO said in their latest advice on masks.
The debate
Euan Tovey, who specialises in the role of aerosols in disease transmission, is one of the 11 Australian scientists who signed the open letter.
He says the WHO's stance on transmission is based on "old fashioned thinking about the behaviour of particles".
Professor Tovey says this was reflected by their official recommendation of 1 metre social distancing.
"One metre is pretty close, particularly indoors ... and we think a lot of transmission comes from smaller particles concentrated within about 1 metre in a room," he said.
Why does it matter
The scientists acknowledge there are still parts of the puzzle of evidence missing when it comes to airborne transmission but say we still have much to learn about large droplet transmission too.
They say until we have a vaccine, all routes of transmission must be interrupted and if the importance of ventilation isn't recognised, there will be "significant consequences".
"People may think that they are fully protected by adhering to the current recommendations, but in fact, additional airborne interventions are needed for further reduction of infection risk," the scientists say.
They also believe the matter is of "heightened significance now" as countries push ahead with re-opening measures.
'It is Time to Address Airborne Transmission of COVID-19' will be published in Clinical Infectious Diseases journal on Tuesday.
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