Bill,
Agreed, absent catastrophe, ~18 months to where we have enough herd
immunity - hopefully mostly vaccine-produced - to backburner this thing
and move on.
I see the chief likely path to this becoming economically tolerable in
the meantime as being an effective antiviral treatment that reduces
severity to the point where death rate drops by a factor of ten or so
(more would be nice.) At that point, with continued "social distancing"
& improved personal sanitation customs, combined with a wide-net
testing/contact-tracing/case-quarantine regime, we might be able to
resume normal economic activity without an unacceptable level of severe
infections and deaths. (I haven't run numbers on that - the 10x
reduction was pulled out of a hat on the assumption that we're able to
tolerate other widespread respiratory bugs with that ballpark 0.1%
deaths/cases. YMMV.)
Henry
On 3/20/2020 7:26 PM, William Claybaugh wrote:
Henry:
We agree even down to your comments about competence and politicians.
My only observation is that quarantine, once it reduces local R0 below one point zero, will have to be maintained until a vaccine is available. Which—as you observe—is not likely to be widely distributed before 18 months from now, optimistically.
Bill
On Fri, Mar 20, 2020 at 8:15 PM Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx <mailto:hvanderbilt@xxxxxxxxxxxxxx>> 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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(941) 360-3100 x101 Sarasota
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