[AR] Re: FW: [NASA HQ News] March 19 Administrator Statement on Agency Response to Coronavirus
- From: Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Fri, 20 Mar 2020 16:23:59 -0700
On 3/20/2020 2:06 PM, Uwe Klein wrote:
Thing I haven't really tried to get a grip on:
You do a number of tests ( with cause for testing assumed
i.e. not shotgun style testing. )
from this you get a certain number of positives : infected.
for the US from official numbers 50+k tests with ~16k infected found
or ~30% positive.
for Germany I could only find 35k in the last week for the last weeks
delta of ~9k positives. 25% ? ~ same domain.
( haven't looked anywhere else.)
When is a point of overtesting reached?
What positives rate should be aimed for to get good coverage?
( obviously testing everybody and his/her hamster is out of the
question at the moment // for ever?
I'd go for shotgun antibody testing later on to get expanded
information including (silent, unnoticed) spread )
I've been following this fairly closely since January, FWIW. Digging
into the numbers from various locales and getting a feel for them.
(Lots of time on my hands, recovering from last year's health problems
while hoping to avoid this year's...)
The thing about testing is, if available numbers of tests are low, tests
will be focused on the most likely cases as indicated by circumstances
(direct contact with known infections) and by really obvious severe
symptoms. Thus, you will see a very high fraction of total tests come
back positive. ~9K positives in ~35K total tests suggests to me that
tests may have been a relatively scarce resource in Germany to that
point. It also suggests that at that point, some significant number of
low-symptom cases existed but had not yet been tested. (The US has been
following a similar trajectory.)
Note that numerous unspotted unquarantined cases will increase the
spread rate, while after more tests are available and the testing net
cast wider, more existing-for-a-while cases will be discovered. The
combination will tend for a while to make the apparent rate of increase
in infections even worse than the real one. Which is likely already
pretty bad. The US is definitely in this phase - known new-cases
increase rate is up near 40%/day again, after dropping for several days
down to near 30% - as are many other places.
South Korea as of earlier this week had tested nearly 300,000 people,
and found about 8000 positives. That's a 2.7% detections per test rate,
and indicative of a much wider net being cast, with testing done at far
lower levels of suspicion. South Korea's current new-cases increase
rate of ~1% a day is likely related to this approach. (South Korea did
start earlier, mind - I'd estimate about 3 weeks - and as of late
February was also at around 30%/day new cases increase. From a much
smaller base, as they jumped on it hard, early - and they've been very
effective at reducing the spread since. Very much worth looking at for
how they're doing it WITHOUT resorting to Chinese-style draconian measures.)
hope this has been of some help
Henry
Other related posts: