This is a twitter thread from Trevor Bedford on why to explosive COVID growth is expected soon.
Explosive COVID Growth Expected
I know that everyone has been (justifiably) distracted by other things, but the #COVID19 epidemic in the US is looking pretty dire with 125,552 confirmed cases reported Friday by @COVID19Tracking.
Please consider this somewhat of a follow up to the thread two weeks ago on circulation patterns across states.
Confirmed cases have continued to tick up across the US, though with the Midwest and Mountain West contributing to most of the recent increase. Data from @COVID19Tracking. If we look across states and plot confirmed cases on a log scale we can see a steady linear-on-a-log-scale trend in the past 4-8 weeks across most states. This pattern is indicative of exponential growth.
Exponential doubling of COVID-19 is proportional to the instantaneous reproductive number Rt at a particular point in time. If Rt is greater than 1 then the epidemic is growing, if less than 1 it’s shrinking. In the following I plot Rt estimates from rt.live.
Rt COVID-19Up-to-date values for Rt — the number to watch to measure COVID spread.http://rt.live/Broadly, Rt varied widely across states in May-Aug corresponding to differing societal behavior and state-level “reopening” policies, but during Sep and Oct states have largely equilibrated in terms of Rt.
Notably, 49/50 states are currently estimated to have Rt > 1 and in 40/50 cases Rt is estimated to be larger on Oct 28 than on Oct 14.
This indicates that the current surge has no evidence yet of cresting. It’s exponential “velocity” is the same or greater than two weeks ago; we’ve not yet seen signs of deceleration.
I’ve written previously about the dynamic relationship between COVID-19 cases, deaths and societal response I expect both to play a role in countering the current surge, but I won’t hazard a guess at this moment as to when this occurs and what we eventually suffer in terms of daily case load.
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