Covid-19 in Braidwood?
[Local experience, but it applies everywhere. The small town of Braidwood is between Canberra and the coast.]
I just returned from Braidwood’s bustling main street, midmorning Saturday 21 March, and it’s clear many Braidwoodians, and Canberrans, haven’t got the message about ‘social distancing’.
There are, plausibly, hundreds of infections in Canberra, and plausibly already some in Braidwood. Let me explain.
Officially there are 6 confirmed Covid-19 infections in Canberra, but there is a delay of around 9 to 15 days between infection and official confirmation. Unrestrained, the number of infections doubles about every three days, and Australia nationally is still close to that rate. It’s that combination of delay and regular doubling that is the problem.
Let’s do the numbers. Symptoms commonly don’t show until 5-7 days after infection, and evidently longer in some cases, so let’s say up to 10 days. Let’s say it takes 1-2 days for someone to consult a doctor. Then it’s 3 days until the results are known. So it’s between 9 and 15 days from infection to confirmation.
Today there are 6 confirmed cases in Canberra, but that reflects the situation 9-15 days ago. After 3 days there would be 12 infections. After 6 days 24 infections. After 9 days, 48 infections. After 12 days 96 infections. After 15 days 192 infections. So let’s say up to about 200 cases in Canberra, right now. 9 days (three doublings) from now there would be eight times as many, 1600 cases, and 18 days from now 12,800 cases in Canberra, with vastly more in the big cities.
So at the moment it seems like nothing is happening and we can carry on as usual. But the virus is spreading, you can count on that, and by the time the problem becomes obvious it is much too late to stop it. That’s how Italy got in trouble.
You can read about the small Italian town of Vo where they tested everyone and found many more infections than they expected, many without symptoms (which means it’s worse than I just estimated). They imposed strict distancing and isolation and today Vo is called the healthiest place in Italy.
Here a very good visual explanation of exponential doubling and pandemics. (The lily pads part is very clear, the buckets metaphor later less clear, but stay with it.)
And there is a deep lesson for us in this pandemic, if we can listen.
So, folks, if you want us to be like South Korea and not Italy, keep your distance, but keep social contact. As Kahlil Gribran says, in The Prophet, “Let there be spaces in your togetherness.”
Pay attention to the messages and new rules. Urge Canberrans not to travel if they don’t have to, and to be mindful and considerate if they do pass through our town. In fact, urge the government to act more quickly and strongly, we are still exposing ourselves to great danger.
Good call, Geoff. We are not used to dealing with cryptic, exponential growth. There is also a good explanatory YouTube by 3Blue1Brown.
I fear there will be many thousands of deaths before a vaccine is found or we acquire sufficient herd immunity.