The one COVID-19 number to watch

ABC NEWS

Story Lab

Updated 10 Apr 2020, 14:14pm
Published 10 Apr 2020, 3:03 am
 

he vast array of data on the coronavirus pandemic can feel overwhelming, as we all try to make sense of how fast COVID-19 is spreading around the world and the relentless daily count of new cases and deaths.

Helpfully, there’s one number that can tell us quickly and clearly whether the coronavirus outbreak is getting better or worse. It’s called the growth factor.

The main thing to understand is this — to be sure we’re staying on top of the outbreak, we must keep this number below one.

And here is how the growth factor for Australia’s outbreak currently looks.

Australia's current
growth factor is0.84
Mar 6
Apr 9
HIGHEST
1.39 Mar 12th
LOWEST
0.83 Apr 6th

What is ‘growth factor’ and why is it important?

Put simply, the growth factor measures how fast the number of new cases is going up or down.

And here’s the key point:

  • If the growth factor is above one, the number of new cases each day is going up. If it stays above one consistently, alarm bells should be ringing.
  • If it’s below one, we’re getting the outbreak under control.

Calculating the daily growth factor is as simple as taking today’s new reported cases and dividing it by yesterday’s new cases. Because these numbers can be a little volatile, we’re using a five-day moving average of new cases for our calculations.

Of course, the growth factor will change over time. Even though Australia’s current growth factor is below one — meaning there were fewer new cases today than there were yesterday — that could change.

But for now at least, things are headed in the right direction.

Australia looks to be successfully flattening the curve but as public health officials keep reminding us, the fight against coronavirus is likely to be a long one.

Even if the number of people sick with COVID-19 gets quite low, the virus could start spreading quickly again without ongoing vigilance.

[Want to see how Australia’s growth factor compares to the US, the UK and other countries around the world? Keep reading, or skip ahead.]

What else should I know?

A figure like this is only ever as good as the data being collected. So when reading the growth factor, there are two extra parameters to keep in mind: community transmission and testing.

The number of coronavirus cases originating overseas is starting to decrease drastically at the moment, and there’s a risk those falling numbers could hide something more worrying — a smaller but rising number of cases caused by spread by community transmission.

Experts say the rate of that local spread may be a better indicator of just how well our physical distancing measures are working.

It’s been difficult to compile data on community transmission. So far, the data we do have only starts in April.

It shows little difference in the growth factors for imported cases and local spread. However, there are about 89 cases still ‘under investigation’, meaning their origin remains unclear.

Australia (community transmission)

current daily
growth factor:0.81
Apr 1
Apr 9
HIGHEST
1.03 Apr 4th
LOWEST
0.49 Apr 1st

Australia (imported cases)

current daily
growth factor:0.82
Apr 1
Apr 9
HIGHEST
0.96 Apr 3rd
LOWEST
0.37 Apr 1st

Another question mark around the data is testing. We will only find cases where we look for them and much of Australia’s testing has been focused on people arriving from overseas and their close contacts.

Even though Australia has tested a high proportion of the population by international standards, Catherine Bennett, the chair of epidemiology at Deakin University, says our high testing rate and low positive rate are a “red herring”.

“If you’re not testing the increasing number of people with symptoms in the community, then you only see what you test for.

“If we can look at that in more detail as we do the breakdown [of community transmission] within Australia I think that’s going to be helpful, because I do think it ties to the lockdown. The lockdown is all about community acquisition, not about the boats that came in four weeks ago.”

The unknown number of undetected cases currently in the community may prove crucial to keeping Australia’s outbreak manageable.

Several states have announced they’re now expanding testing criteria to include a broader cross-section of the community. So it’s important to remember that any rise in the growth factor could be, in part, a result of more widespread testing.

“As we expand our testing we expect it to go up but that doesn’t necessarily mean community cases are going up, it means that testing is broadening to capture them,” Professor Bennett said.

Finally, it’s worth remembering that even though the growth factor is a great litmus test for how well we’re keeping Australia’s outbreak in check, other numbers are important too.

How are other countries doing?

Now that we understand what growth factor means, it can also provide a useful insight into outbreaks around the world — and how different countries are faring in their efforts to bring coronavirus under control.

The following charts focus on the countries with the largest overall coronavirus outbreaks around the world, as well as some of Australia’s nearest neighbours.

 

As you compare those global figures, it’s even more important to factor testing regimes into your thinking. If one country is testing a lot and another is testing very little, it’s going to have a major impact on how their growth factors stack up.

See charts at this website https://www.abc.net.au/news/2020-04-10/coronavirus-data-australia-growth-factor-covid-19/12132478

 

About the data

  • Australian case numbers are sourced from federal, state and territory health department media releases and press conferences and compiled by ABC News. For countries other than Australia, the number of cases comes from data compiled by Johns Hopkins University.
  • Health authorities update their figures at different times of day, so the numbers shown do not reflect the same point in time in each jurisdiction.
  • Growth factors have been calculated using a five-day moving average of new cases.
  • Where there are fewer than five cases per day on average over the past five days, no growth factor is calculated. This is represented by a grey dotted line on the charts.
  • It’s important to note that all data in this story represents confirmed cases, which includes presumptive positive cases actually identified by authorities. The actual number of cases in each country is likely to be higher, as an unknown proportion of people with the virus would not have been tested. Therefore, the numbers’ accuracy will also vary depending on how much testing each country is doing.

Credits

  • Reporter & Developer: Simon Elvery
  • Designer: Ben Spraggon
  • Additional Reporting: Matt Martino
  • Editor: Matt Liddy

You need to be a member of 1Eyed Eel to add comments!

Join 1Eyed Eel

Votes: 0
Email me when people reply –

Replies

  • Vince articles from the ABC are banned on the site . 

    • lol, I put them for my very special friend Poppa. He loves them

       

       

This reply was deleted.

Latest comments

LB replied to Prof. Daz's discussion R4 V TIGERS: FREUD SAYS ‘WORK THROUGH’ IT, DEAR EELS
"The thing about this game that is curious and worrying to me is are Wests the real deal or was last week just a mood. I tipped Wests to beat Cronulla last week for a few reasons. 1) Was not convinced on Cronulla's past 2 performances where they were…"
25 seconds ago
BEM replied to Cʜɪᴇғ -'s discussion Big News On Lomax
"Sivo is back this round"
1 minute ago
Bup replied to Poppa's discussion Players and Values and Judgements to make
"Lomax is nearly the perfect player Parra need to aquire.
The story's about his attitude and immaturity are prevalent and he's in a environment he doesn't want to be in .
The value here is you can get yourself a footballer for under market value due…"
16 minutes ago
Prof. Daz’s discussion was featured
Sigmund Freud once said that “one day, in retrospect, the years of struggle will strike you as the most beautiful”. With the Eels on-field general and kicking maestro, Mitchell Moses, out for up to 8 weeks with a fractured foot, the Eels will need…
39 minutes ago
Jake replied to Cʜɪᴇғ -'s discussion Big News On Lomax
"Could it be Maika to make way for Lomax.
Round 4 deadline. Maika suspended until round 4. Hmmm"
42 minutes ago
Poppa replied to Poppa's discussion Players and Values and Judgements to make
"Well Lomax will be a lot more expensive, Carty would have been on minimum for most of the time and probably only 350/400 now. Carty is not that marketable unless he sell himself attached to the coach LOL"
1 hour ago
Poppa replied to Poppa's discussion Players and Values and Judgements to make
"Thanks Hoe, agree with what you said.
I tried to specifically generalise about player valuations and use Lomax as an example. To answer Sluggo who was taking the piss, I can accept the premise he is making but I personally had overlooked Waqa as an…"
1 hour ago
Poppa replied to Poppa's discussion Players and Values and Judgements to make
"Well thought out and expressed Slippery.... you raise good points about circumstantial valuations."
1 hour ago
BEM replied to Cʜɪᴇғ -'s discussion Big News On Lomax
"Our dominant half is getting older and if we lose Sanders, there is no real alternative. 
Our forwards are getting older as well.
Our "premiership window" is closing fast so we need quality experienced players now instead of waiting to see if the…"
1 hour ago
Poupou Escobar replied to ParramattaLurker's discussion Round 4 Team List v Wests Tigers
"He might be but he's definitely not a better tackler."
2 hours ago
Poupou Escobar replied to Johnny Suede's discussion Clubs monitoring status of Jake Arthur
"Comparing records in different years and at different clubs is apples and oranges. At least compare their form in reserve grade in 2024. Arthur is well ahead:
Official The Knock On Effect NSW Cup profile of Jake Arthur for Bla...
Official The Knock…"
2 hours ago
Slippery. replied to Poppa's discussion Players and Values and Judgements to make

 The thing is, players values change regularly. Not only at their current club but with many clubs.  For example. Before the Eels game last Sunday,  Lomax was more valuable to the Eels than after the successful debut of Blaize. Last week the Eels…"
2 hours ago
Electric Eel 2 replied to Poppa's discussion Players and Values and Judgements to make
"One name. Bryce Cartwright! Look at the difference between when we got him until now. Lomax will be no different in my opinion."
2 hours ago
JB. Prints of Parra replied to Cʜɪᴇғ -'s discussion Big News On Lomax
"Lomax wing outside Pensini.
Russell back to Fullback in NSW Cup.
Sivo and Blaize on the other side.
Bailey and Harper can be let go next year.
Richie P as back up."
3 hours ago
LB replied to Poppa's discussion Players and Values and Judgements to make
"Yeah Lomax wont fix all our issues, but he does improve others. Those slight improvements could be enough to go over the line. If Lomax can fix some issues than he is worth bringing in as you bring players in to improve your team.BA tried to get a…"
3 hours ago
Inside Info replied to Poppa's discussion Players and Values and Judgements to make
"I actually think Lomax is good for us, he has that flair we lack, yes at times it doesnt come off, but under a stronger coach like BA he will be more selective. He is someone can use through fullback, wing & center. He would be worth 600-650k. If we…"
4 hours ago
More…

 

Big News On Lomax

The inside information and this is from a credible source,  - This Saturday will be the last game Lomax will play in the red V.  Make of this what you will.  Parramatta are odds on and have made it known through the media that we are after…

Read more…
114 Replies · Reply by BEM 1 minute ago
Views: 3100

<script src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- Sidebar -->
<p>&nbsp;</p>
<script>// <![CDATA[
(adsbygoogle = window.adsbygoogle || []).push({});
// ]]></script>