Australian Reports of the Virus Spread

[lovetravellingoz]

Sutton gave an illustrative example yesterday.

"I talk about the R-0 for this virus. It might be 5. That means if you are not altering your behaviour, if are you not doing contact tracing, every person passes it on to five others.​

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"Clearly that is not happening here. We are chasing down every case, we are chasing down their primary contacts but we have seen a growth of probably a dozen primary close contacts for that first case to thousands upon thousands.​

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If someone panicked, it is because they are reacting to what he gave an example of what might be if absolutely nothing was being done (ie this is not the current situation), which as he stated at the time "Clearly that is not happening here"


Cheng has clarified today that the current theoretical Ro being used for the current outbreak and strain is 3.75. This is more than the 2.53 value used at the time of the second wave in Victoria relevant to the strains in circulation then..

 

[Lynda2475]

"We've got to run this thing to ground otherwise people will die," Victoria's acting state Premier James Merlino said, describing this strain of the virus as "quicker and more contagious than we have ever seen before"

** Not quicker than we have ever seen before and not more contagious than (actually the same) varieties which have escaped HQ in other states

 

[dajop]

Honestly 3 cases a day is something we should be able to easily manage.

Agree totally on this. We’re surviving* here in Singapore on 20 cases a day, usually 5 or so initially unlinked.

And it seems that if the 3 cases a day happen in most of Australia (including most of Victoria), they seem to be managed well (snap lockdowns based on single cases in WA notwithstanding) Get into the outer north or outer west of Melbourne, for some reason 3 can turn into a bigger number much quicker. This was even predicted at the outset of the pandemic. Various reasons why I guess

* although some businesses are really suffering, particularly higher end restaurants , poor quality hawkers and alcohol related venues. And of course the tourism sector.

 

[jakeseven7]

Wouldn't be any partisan politics creeping into this thread (yet again) would there be?

They don't fearmonger ... they're not doing enough... people don't get tested and move about the community spreading the virus.

They fearmonger, and OMG it's lying governments, they're misleading the people

Too fast to lock down, too slow to lock down

Too fast to lift restrictions, tool slow to lift restrictions.

Not cautious enough, too cautious.

Victorian government can never do anything right. Ever.

Didn’t the Victorian government also invent the AZ vaccine and isn’t everyone in Victoria also a GP

 

[SydneySwan]

Didn’t the Victorian government also invent the AZ vaccine and isn’t everyone in Victoria also a GP

And AFF is home to many of Australia's top epidemiologists!

 

[Must...Fly!]

And AFF is home to many of Australia's top epidemiologists!

Got no problem with them (except the ones that shop around quotes to any paper that will take them). But when what the best (i.e. on advisory panels) say & what the government says doesn't match up, I think one is right to ask why.

 

[SydneySwan]

Todays ABC blog says PM is now saying "three cases per day, averaged over three days" Why this now increased intolerance? When did that change ?

Honestly 3 cases a day is something we should be able to easily manage.

I think Scotty was having dinner with Jenny at the Lodge one night when Jenny said 'You know this definition of a hostpot as 30 cases in 3 days. How would you feel if one of our girls caught Covid in this scenario? Don't you think it should be 3 cases?'

And Scotty quietly updated the definition to 3.

 

[lovetravellingoz]

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Got no problem with them (except the ones that shop around quotes to any paper that will take them). But when what the best (i.e. on advisory panels) say & what the government says doesn't match up, I think one is right to ask why.

I think that is one reason why they had Prof Cheng at the Vic Presser today to explain things as he is in that category: "what the best (i.e. on advisory panels) "

 

[Lynda2475]

So ABC has either misquoted the PM or the PM quoted the regional hotspot definition. The official definition is below, what is new is the blue text and what have been leveraged for the current outbreak (even though the risk of higher transmissibility is not agreed):

Triggers for consideration of a hotspot include:

Any area where; There is the occurrence of a case of infection in the community1 with a more transmissible variant of SARS-CoV-2 and opportunities for wide community exposure.

In a metropolitan area where; The rolling 3 day average (average over 3 days) is 10 locally acquired cases per day. This equates to over 30 cases in 3 consecutive days.

A rural or regional area where; The rolling 3 day average (average over 3 days) is 3 locally acquired cases per day. This equates to 9 cases over 3 consecutive days.

https://www.health.gov.au/sites/default/files/documents/2021/02/listing-areas-of-covid-19-local-transmission-as-hotspots.pdf

 

[bcworld]

Next HQ debacle waiting to happen?

Cops probe possible breach after shock photo of inside quarantine hotel

EXCLUSIVE

www.news.com.au

 

[lovetravellingoz]

Update of the Victorian Outbreak Graphic.

 

[bcworld]

Might need another update!

https://twitter.com/i/web/status/1400360441243738115

 

[lovetravellingoz]

Might need another update!

https://twitter.com/i/web/status/1400360441243738115

Amended version. The Metricon home Case (Botanical Display Homes) already had a note on it as this was flagged as a possible false positive a couple of days ago.

 

[Lynda2475]

Interesting that the two reclassified cases were the ones being used as "proof" (now disproved) evidence of fleeting contact transmission.

 

[lovetravellingoz]

Interesting that the two reclassified cases were the ones being used as "proof" (now disproved) evidence of fleeting contact transmission.

Incorrect as there are other fleeting cases.

The cases had been cited by health officials as two examples of at least half a dozen where the virus was transmitted through "fleeting contact" between strangers.​

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Plus the Metricon case was previously reported (and before Sutton spoke at the Vic Presser) as having returned a negative test after the first positive test and so was likely to have been a false positive. Further testing has now confirmed this.


Plus t

 

[nutwood]

From ABC

By Simon Smale

Variants are shown to be more infectious: Dr Cheng​

Dr Cheng is being asked about whether or not a particular strain is spreading faster than another.

How much more contagious is it? Dr Cheng was asked.

Dr Cheng was asked about what the R-0 number was, as opposed to giving an estimate.

Dr Cheng said the reduced number of interaction meant that pre-lockdown, "we think that the R effective was 1.1 to 1.3".

How are they deriving these figures? The sample size is simply not large enough for anything but wild guessing and that's exactly what they are trying to quantify.

 

[suze2000]

And AFF is home to many of Australia's top epidemiologists!

Certainly the most opinionated one

 

[lovetravellingoz]

How are they deriving these figures? The sample size is simply not large enough for anything but wild guessing and that's exactly what they are trying to quantify.

I agree. Reff over such a small number of cases and brief period cannot be accurate. You really need more a flu size sample. Though having said that the flu is so now that Reff's for that would not be accurate either.

Reff's are also normally calculated over a 7 day period as I mentioned up thread.

Cheng and others have been more basing it how it being more infectious based more on:

• how cases have been presenting
• that some cases seem to have been infected, and they have infected others more quickly. ie In a day. And that generations have been coughulatively quick
• that there are some cases without a direct interaction of the two people. ie Butcher club had cases from brief customer interactions of people buying meet.

Now countering that there are theories that some of this, but not all may be due to very efficient contact tracing etc.

 

[nutwood]

The logic is unsound. Person A may pass it to Person B on the street but we don't know how many people Person A did not pass it to. They may have been really close and intimate to Person C without passing it on.
The only way meaningful figures can be derived is with large numbers or very controlled experimentation where every possible variable has been eliminated. Otherwise it's the same as saying I flipped a coin ten times today and got eight heads, therefore flipping a coin has an 80% chance of heads.

 

[lovetravellingoz]

The logic is unsound. Person A may pass it to Person B on the street but we don't know how many people Person A did not pass it to. They may have been really close and intimate to Person C without passing it on.

Though that is not how Reff is calculated. How many people were not infected is not part of the calculation.

What I think you are describing there is the Attack Rate.

Attack Rate​

Attack rate is the proportion of exposed people that become ill. ​

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Estimation of the effective reproduction number (Reff)​

The effective reproduction number, Reff, is representative of how many people are infected by a single person on average. It is calculated based on the ‘serial interval’, which is the time between clinical onsets, using a method developed by colleagues at the London School of Hygiene and Tropical Medicine [Abbott, S., Hellewell, J., et al Estimating the time-varying reproduction number]. This method accounts for reporting delays, to account for whether an observed drop in the number of cases is reflective of an actual drop in the number of cases.​

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As an example, if everyone was infectious for 7 days, and there was 10 cases a week ago, and 20 cases today, then we know that every person passed the infection to two other people (on average), and so Reff=2.​

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The effective reproduction number is smoothed over a 7 day window to reduce the impact of localized events that may cause large fluctuations.​

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Department of Health and Human Services Victoria | Theoretical modelling to inform Victoria’s response to coronavirus (COVID-19)

The Victorian Government has released modelling to provide greater understanding of the spread of coronavirus in Victoria.

www.dhhs.vic.gov.au

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PS Though I do agree on your point that the sample size in this case is too small to make for a statistically accurate number.