4 ms·

Why start today? There were 5 cases confirmed in the US as of Jan 25, 50 days ago, at least some of which appeared to be community transmission. Applying this m

by mokus 7y ago

Why start today? There were 5 cases confirmed in the US as of Jan 25, 50 days ago, at least some of which appeared to be community transmission. Applying this math for the US as a whole with the 10x initial factor gives 5 * 10 * 2^(50/3) ~= 5.2 million cases TODAY. If we don’t believe that number (or do we? Hell, I have no idea at this point), why do we believe the same math with today as initial conditions?

jessriedel 7y ago
I don't think the OP math is sensible. (At the absolute most basic, if you're trying to be "conservative" about modeling the effects of social distancing on exponential growth, you should cut the growth rate rather than cutting the absolute number by some percentage.) However, that said: it makes more sense to model growth as exponential once you've documented community transmission as the primary driver. When the US had 5 cases, they were all imported from China and basically contained.
- mokus 7y ago
  I had recently seen a claim that among the first 5 US cases, some had been apparent community spread, but searching back now I can’t find any substantiation for that claim. So yeah, looks like my assumptions here were wrong. Sorry. Using the same math from feb 26 instead, which is the date I saw a CDC article published about first suspected community transmission, the figures are instead 15 * 10 * 2^(18/3) = 9600, which is more plausible. In any case, the calculations are extremely sensitive to the growth rate which, as you say, is also a thing we can control by modulating behavior. The extent to which we will actually do so is debatable, of course. As far as I’m aware I’m still expected to show up on site for work tomorrow.
  - Izkata 7y ago
    Using the "Total Cases" graph (logarithmic view) here [0], it looks like Mar 1 is when the US's reported cases became exponential, and is probably a better baseline. [0] https://www.worldometers.info/coronavirus/country/us/ https://www.worldometers.info/coronavirus/country/us/

by mokus 7y ago

jessriedel 7y ago

I don't think the OP math is sensible. (At the absolute most basic, if you're trying to be "conservative" about modeling the effects of social distancing on exponential growth, you should cut the growth rate rather than cutting the absolute number by some percentage.) However, that said: it makes more sense to model growth as exponential once you've documented community transmission as the primary driver. When the US had 5 cases, they were all imported from China and basically contained.

mokus 7y ago
I had recently seen a claim that among the first 5 US cases, some had been apparent community spread, but searching back now I can’t find any substantiation for that claim. So yeah, looks like my assumptions here were wrong. Sorry. Using the same math from feb 26 instead, which is the date I saw a CDC article published about first suspected community transmission, the figures are instead 15 * 10 * 2^(18/3) = 9600, which is more plausible. In any case, the calculations are extremely sensitive to the growth rate which, as you say, is also a thing we can control by modulating behavior. The extent to which we will actually do so is debatable, of course. As far as I’m aware I’m still expected to show up on site for work tomorrow.
- Izkata 7y ago
  Using the "Total Cases" graph (logarithmic view) here [0], it looks like Mar 1 is when the US's reported cases became exponential, and is probably a better baseline. [0] https://www.worldometers.info/coronavirus/country/us/ https://www.worldometers.info/coronavirus/country/us/