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To the "Two Threads" Item.
Dr. Terry Jones is the founder of Jon Software, based in Barcelona. The company’s business is advanced information software. He e-mailed what follows in response to my “Two Threads” post from earlier this morning. It’s smart and worth reading:
Dear John —
There's nothing to object to in those posts - unlike many (almost all) things that are being written. One assumption in the Specht analysis is that people's behavior will be unchanged over time, which does not correspond to what actually happens. By this I mean that the rate of infections can/will drop dramatically as people get serious about isolation. The recent confirmed case counts in China are an example - when you have no one on the streets, at schools, traveling, etc., the numbers go way down, but that doesn't mean the potential of the outbreak has changed (it has an important impact on peak medical demand, as mentioned in the article). So it's not realistic to project into the future as though behavior will be unchanged. This is similar to people's reaction to hearing an R0 number: R0 is defined in terms of how many infections on average could be expected to take place if an infected person went into a totally naive population. The problem of course is that the population is not naive for very long, so the dynamics (and hence infection numbers) change over time. The R0 number is just part of very simplistic (broad-brush) epidemiological modeling. There are many other factors that have huge impact on infected numbers over time (as mentioned above). So while a simplistic doubling analysis will still result in some sort of exponential growth even if its basic parameters are off (as Specht says), if the overall behavior of the population radically changes, an exponential model can be exponentially wrong :-) Some comment could be made about what happens to the virus in the meantime as we try to slow its spread. No one knows the answer to that, only that there are definite (i.e., I mean very specific genetic ways) in which the virus might be able to become worse from the human POV (lab testing, in progress, is needed to assess some of these possibilities - but it's too early to know the possibilities, and they may not be knowable given finite time/resources and what can actually be done in models in the lab). It could also attenuate.
The social aspects of the posts are something that is very often overlooked, so it's good they're mentioned. Although there are very clear differences between SARS-CoV-2 and the 1918 influenza as a virus, there might be quite similar social and economic fallout. I wrote a few comments about this back in the 2009 pandemic: http://blogs.fluidinfo.com/terry/2009/04/30/ok-its-a-pandemic-now-what/.
That side of things is hugely overlooked, IMO, including by (some) people who do pandemic preparedness planning who haven't even read the obvious books (I mention a couple of them in that post, and there's also the recent Pale Rider by Laura Spinney). There's lots of chatter online about doubling and growth rates. For light math entertainment, it's possible to instantly calculate that the Specht doubling period of 6 days corresponds to a daily interest/growth rate of 12% using the very simple and also accurate Rule of 72 estimate. I wrote about it at http://blogs.fluidinfo.com/terry/2011/06/20/back-of-the-envelope-calculations-with-the-rule-of-72/ Nothing can double every 6 days for very long.
There are various things that could be said about this particular virus, but I don't want to go there. I would only trust specific things written/said about this virus coming from actual coronavirus researchers who have worked in the lab (and I mean before this current virus - i.e., on SARS or MERS or one of the other human coronaviruses), not virologists in general, not people who only do bioinformatics, etc. Suddenly there are coronavirus experts everywhere. Suffice to say, there is a ton of wholly inaccurate and too-speculative stuff out there. And some truly shocking, hypocritical, opportunistic and even (IMO) criminally negligent behavior, including (unfortunately) in the academic world. Some of it is off-the-charts ugly.