(Tue, 19 Dec 2006 22:42:51 GMT) How fast will a pandemic go? Have you looked at the speed of a pandemic? Velocity denotes acceleration, which a pandemic will attain. You can use your own CFR.
I’ve put together a spreadsheet, but am unable to get it into a form that will work here, so
the two variables are:
1. Average number of people spread to “R”
2. Average number of days to spread to average number of people “D”
And Patient Zero - First h2h patient who lives work in a major urban/metro setting worldwide
The results are interesting…
with R=5 and D=2
Day #infected
0 1
2 5
4 25
6 125
8 625
10 3,125
12 15,625
14 78,125
16 390,625
18 1,953,125
20 9,765,625
22 48,828,125
24 244,140,625
26 1,220,703,125
So, after less than one month, more than a billion are infected. But, the critical OMG moment will probably come at day 10 that FW readers will realize a problem, and after day 14, it’s probably already in the US.
The numbers are worse if R is even higher…
at R=7 day 8 is 2,400 infected and day 14 is up to a million infected.
I started to think about this after the Idaho duck episode. Just how high does R get? TBTB are using R values at 2 or less. Which gives a huge sense of time.
at r=2 after 30 days only 32,000 are infected, and after 60 days you reach a billion.
If you start stretching out how long it takes to infect people, the timelines get way out too.
at r=2 and D=5 it takes 30 days to reach 64 and 90 days to reach 250,000.
How hard is it to imagine that someone infects 4 other people in an urban environment? And that it only takes 3 days from initial infection to spreading the germ to those 4 others.
Well for me it doesn’t take a lot of effort.
I’m willing to bet that initially when the pandemic happens at the start R will be really high like R=8 and the time to infect others D=4
that means that at day 12 500 are infected, and day 16 4000 are infected.
What are the practical implications of these calculations for fluwikians? We only have to watch out the jump from high double digits to triple digits to know that a pandemic is underway. And the velocity of the jump will give us an indicator of how quickly the pandemic will progress as well as blow over.
