On a more somber note, the actual death rate could be as high as 5.6 - 15%.
According to this paper to properly calculate the mortality rate you
have to account for the incubation period, which is assumed to be 14
days, so that mortality rate has to be calculated using the infection
rate 14 days prior.
https://www.thelancet.com/action/showPdf?pii=S1473-3099%2820%2930195-X
Ivan
On 21/03/2020 13:14, Henry Vanderbilt wrote:
Bill,
R0 estimates vary all over the place. And the actual value of course is going to vary with local customs and practices, as modified by local containment measures. Probably futile trying to estimate R0 now; it's something you figure out after the dust has settled.
One data point on how far this thing spreads in a given population, albeit far from a pure one: 3700 people total on Diamond Princess, all tested, current near-final positive count 712, for about 20% total infected.
Now, initially the spread on Diamond Princess was uncontained. Then, there was a disorganized incompetent attempt to contain it. Then the continuing flow of new infections scared them into getting competent. So it's definitely not any strong indication of where herd immunity would become effective in an uncontained spread.
I suspect it is, however, a decent approximation of the likely sequence in your average densely populated US city with an incompetent political-hack local government. Uncontained, then incompetently contained, then hugely scary results, then competently contained. If only because the state and/or the Feds step in.
Places that are well-enough run to skip the middle two steps will see a lot fewer overall cases, I suspect.
Places that are badly enough run that they can't reach step 4 on their own are in for a really rough ride. (NYC now is at step 3 - known infections increasing at ~70%/day - and the Mayor is apparently not taking advice.)
A place that averages the same total 20% spread as Diamond Princess and /doesn't/ run out of Respiratory ICU beds should see about 200 deaths per 100,000 population. (~5% of infectees will need a ventilator, ~4 out of 5 of those will then be saved by the ICU treatment.) A place that does run out of RICU beds - US average is about 50 such beds per 100,000 population - could see up to 1000 deaths per 100,000. (More, of course, if total spread ends up higher than 20%.)
~50 beds per 100,000 of us should make it abundantly clear why containment measures sufficient to time-spread the infections peak a LOT are very important. (Current initiatives might in time raise that to 60 or 70 beds. One of the major bottlenecks is years-trained personnel.) Entirely aside from such containment measures buying time for effective acute-case treatments (another month at best, more likely a few months) and a vaccine (likely a year or more) to arrive.
Henry
On 3/20/2020 6:30 PM, William Claybaugh wrote:
John:
After looking—again—I am not able to find the source for you assertion that R0 is between 1.5 and 3.0. From where are you getting these numbers?
Note that because some localities will not Institute quarantine, it follows—given exponential growth of infection—that w/i no more than a few months we will have natural experiments that accurately measure whether herd immunity is achieved at as little as 30% infection.
Today, I remain unaware of data indicating that R0 is not comparable to smallpox, but definitely open to new data.
Bill
On Fri, Mar 20, 2020 at 5:01 PM John Schilling <john.schilling@xxxxxxxxxxxxxx <mailto:john.schilling@xxxxxxxxxxxxxx>> wrote:
On 3/19/2020 7:32 PM, William Claybaugh wrote:
For herd immunity, you only need 1-(1/R0) of the population to
have had it, which means you'd need an R0 of 10 to infect 90% of
the population. R0 estimates for COVID-19 range from 1.5 - 3.0,
so 35-55% of the population, not 90%.
And that's for doing absolutely nothing. Long-term, public health
measures like contact tracing and behavioral changes like more
handwashing will knock R0 down from that initial 1.5-3.0 range.
If it goes below 1.0, and the virus is reduced to sporadic
outbreaks without needing herd immunity.
90% of the human population being infected is an innumerate
paranoid fantasy, and we don't need those right now.
John Schilling
Anthony:
It will undoubtedly pass but not until about 90% of the human
population has had it and survived (herd immunity) or until a
similar fraction has had some combination of having had it or
had a vaccination.
Given pressure, the usual 18 months to get a safe vaccine might
be reduced to 15 months; assuming 6 months more to vaccinate
everyone who hasn’t had it, I get an optimistic 18 months before
this is over, locally.
When the Chinese back off of their current quarantine, look for
a second wave of infections to follow: less than 1% of the
Chinese population is now immune from having had it and survived.
Bill
On Thu, Mar 19, 2020 at 7:18 PM Anthony Cesaroni
<anthony@xxxxxxxxxxx <mailto:anthony@xxxxxxxxxxx>> wrote:
Next year. This will pass.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
_http://www.cesaronitech.com/_
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