
We’re Testing the Wrong People - elorant
https://www.theatlantic.com/ideas/archive/2020/04/were-testing-the-wrong-people/610234/
======
polygotdomain
I think this article is getting things out of order. The question right now
shouldn't be who to test, but rather how do we increase the volume of testing.
The article states that we should be running 500k tests a day, as if we're not
simply because we choose not too. Right now we don't have the capacity and so
we can't scale up at all.

Why don't we have the capacity? Well the complete lack of coordination and
leadership at the federal level means that each individual entity, whether it
be state level government or a private entity, is having to do everything from
scratch. That means developing SOPs, procuring supplies, and validating both
the processes and reagents. This is being done on emergency orders as well, so
some of the standards are relaxed to quickly get things up and running.

There's also a shortage of reagents and kits because we didn't have or need
this testing just a few months ago. There's also international competition for
these resources, and because the US has decided it doesn't want to actually
work with or coordinate with other countries, it's a free for all.

Because everyone's frantically working on the same thing, but looking out for
themselves it also means that true high throughput solutions are slow to
develop as well.

I could go on and on, but it's a clusterfuck and no one at the federal level
either A) seems to care or B) thinks that it's their responsibility.

Source: wife is currently in charge of starting up Covid testing

~~~
makomk
There's, frankly, probably not enough reagents and consumables on the planet
for the US to achieve 500k tests a day. As far as I know no country anywhere
has managed this level of testing. Germany - who've been doing the best at
testing lately - have been stuck at about 50,000 tests a day for a few weeks
now, maybe even decreasing slightly. If you take into account the difference
in population, that's only the equivalent of the US doing 200,000 tests a day
- and of course scaling up to a larger population is harder. That doesn't stop
the American press making it sound like not achieving those 500,000 tests a
day is the result of some uniquely American political failing though.

~~~
polygotdomain
100% there is a shortage of reagents and kits. There are certain countries
that are not letting reagents and kits ship out, and we are in no position to
call them out on that.

>That doesn't stop the American press making it sound like not achieving those
500,000 tests a day is the result of some uniquely American political failing
though.

I don't think we're unique in where we are in comparison with other countries
as far as testing, but we are in a unique position in regards to being able to
put some strong leverage on getting other countries to work together to
respond to this pandemic. We're not doing that and as a result, other
countries are having to "roll their own" response to this pandemic just like
we are. The lack of coordination within our country is putting us at a unique
disadvantage, even if we had better coordination world wide.

This pandemic is a exceptional global crisis in a way we've never seen before,
and thus should've led to a addressing it at a global scale in a way we had
never seen before. Instead the global response has been crippled in numerous
ways at various different points in time.

The American political failing is in not being the true world leaders, and the
world is, IMHO, worse off for it.

------
alex_young
The only data that is somewhat reliable in this pandemic is COVID deaths.
Testing the population that is very sick / dying is crucial to understanding
the baseline for the worst part of the problem.

Once you have that under control, and we are not nearly there yet, you have to
get every first responder tested regularly so you can prevent them from
spreading the disease and give them some assurance that coming to work isn’t a
death sentence.

Next we have to focus on getting a baseline of the population regularly tested
to estimate the spread of the disease. This should be randomized and
geographically distributed so we can start to obtain reliable data about the
spread of the disease and deploy resources proactively.

~~~
yason
Deaths can lie too. What does it take for a death to be labelled as covid-19
death? That the person who died was merely tested positive, or do they do
autopsies for all those who tested positive? How about covid-19 deaths that
aren't counted as covid-19 deaths, for a reason or another? How about people
dying less of regular influenza this year because of covid-19 and lockdowns?

Even looking back at monthly 2020 deaths in comparison to earlier years might
not truly reveal the final impact of covid-19.

~~~
cm2187
In the US, if the person tested positive, it is classified as covid19 death.

Also it seems that 98% of covid19 deaths have at least one comorbidity, 75% at
least two. So I would expect that in many cases the virus may have just
accelerated something that would have happened within a few months anyway. So
you kind of need to look at how the full year death rate evolved to have an
idea of the net impact of the virus.

~~~
ajross
That's a misunderstanding of how death works. Everything is a comorbidity on
some level.

> just accelerated something that would have happened within a few months
> anyway

That's absolutely not what this means. Asthma is a comorbidity. Are asthmatics
just a few months from death? I have hypertension, am I about to kick the
bucket? Sixty percent of the US population (no doubt including many of the
posters on this very thread) are overweight, yet somehow we keep coming back.

Almost nothing kills "by itself". Everything adds up, and eventually the body
stops working. Other diseases work this way too, yet you don't complain that
yearly influenza deaths are inflated. Would you have argued that AIDS deaths
were "really" due to the final infection and not HIV?

~~~
cm2187
The study I got these numbers from doesn't seem to classify asthma or obesity
as a comorbidity. The largest ones are hypertension, diabetes, ischemic heart
disease, atrial fibrilation, active cancer in past 5y, heart failure, COPD,
dementia, stroke and chronic liver disease. Not familiar with all items in
this list but some seem pretty serious.

~~~
ajross
So you think that stroke victims and retirees with dementia are just months
from the grave? FWIW: I've personally been living with diagnosed atrial
fibrilation for almost three decades. Diabetes is, literally, a lifelong
illness for its sufferers.

In fact, please cite me _any_ of those factors which will reasonable by
expected to kill you in months. Even heart failure and cancer patients tend to
live years to decades with treatment.

~~~
cm2187
Of the people who died of this virus, yes, it is likely that a not
insignificant percentage were in pretty bad shape. We are not talking about
the whole population who have these comorbidities in the country.

------
munificent
_> Another promising pathway is to pool many tests and run them together. If a
pooled sample tests negative, everyone in the pool is negative. If it is
positive, the members of the pool can be tested individually._

Well, it took a global pandemic, but we finally found a use for bloom filters!

~~~
LolWolf
This idea is called group testing [0] and has been used by the army for quite
a while. It is also a well-studied problem in information theory as a (useful)
basic model and we know optimal solutions to it.

What is surprising is that group testing tells us that we can actually _do
better_ : the specific construction you pinpoint the people who come up
positive, without needing to have a test for each person [1] and this result
is optimal in the expected number of tests. I'm surprised that most labs
haven't already been doing this (but I would suspect some have).

Wootters has wonderful notes on the mathematical background for this—I really
recommend them. [2]

\-----

[0]
[https://en.wikipedia.org/wiki/Group_testing](https://en.wikipedia.org/wiki/Group_testing)

[1] Of course, we require an upper bound on the total prevalence, but even a
weak upper bound yields fairly good savings in testing.

[2] Page 3 on of
[http://web.stanford.edu/~marykw/classes/CS250_W18/lectureNot...](http://web.stanford.edu/~marykw/classes/CS250_W18/lectureNotes/Lecture8-compressed.pdf)

~~~
LolWolf
Gah, I've passed the editing window. If it's confusing to read, it is supposed
to say:

> the specific construction _lets_ you pinpoint the people who come up
> positive

------
RandallBrown
I've been saying this since the beginning of this whole thing.

I don't understand why we haven't focused all of our testing on people that
_aren 't_ sick so we can catch the asymptomatic cases that are out in the
world spreading it to everyone.

~~~
godtoldmetodoit
I've been wondering why there hasn't been more programs to test representative
samples of individuals, just like a political poll.

If I was in a Governor's or Mayor's shoes right now and I know there aren't
enough resources to test everyone, I'd want some data like that to work with
to make policy decisions.

While you are in the process of opening things back up, you keep a close eye
on your daily/weekly representative sample numbers to see if anything needs to
be dialed back. It gives you much closer to immediate feedback.

I suppose the immediate problem is getting a hold of a representative sample
of people willing to be tested, but that feels solvable. I'm sure I'm not the
first one to think of it, just curious why it isn't being done, as it feels
immensely useful (maybe this is just the 538 political nerd in me wanting
virus polls?).

~~~
scott00
The confidence intervals are wide enough it wouldn't be very useful. If you
sample 1000 people and get 0 positives, the 95% confidence interval is 0% -
0.36%. If you're the governor of Illinois, with a population of 12.67 million
people, that upper bound equates to 45,612 people: far, far too many to handle
with contact tracing and isolation. So you need to look to other metrics to
make the decision about whether to issue or revoke a stay at home order.

So what are they looking at? Basically, if they have any evidence of community
transmission, they need to issue the order or keep it in place. That means
that if there are too many symptomatic people to even attempt contact tracing,
you're not even close. Once you're low enough you can do contact tracing, you
wait until you have a handful at most of symptomatic people you can't trace
back to a known case. Until then, all you can do is keep the stay at home
order in place, buy/beg/borrow/steal ventilators and PPE, and build testing
and contact tracing capacity.

------
losvedir
I appreciate the HN title ("We're Testing the Wrong People") in contrast to
the article title ("Without More Tests, America Can't Reopen"), even though
it's usually against policy to have them be different.

But the HN title is actionable: if we can change our testing policy and deploy
our tests more usefully, that's great to know and eminently achievable.

But "not testing enough" isn't really actionable. There's a shortage of tests
because there's a shortage of the raw materials that goes into making the
tests. The U.S. already has tested far and away more people than anyone else,
and is second only behind Italy in tests per capita, and has a "positive test
to test" rate roughly in line with (as low of a rate as) any other country's
rate. See [0] and related charts.

"Just test more" isn't really useful at this point.

[0] [https://ourworldindata.org/grapher/full-list-total-tests-
for...](https://ourworldindata.org/grapher/full-list-total-tests-for-covid-19)

~~~
ajross
> The U.S. [...] is second only behind Italy in tests per capita

Where are you getting those numbers? I don't think that's correct. The
Worldometer data may not be the best, but they have the US well down in the
middle of the pack at ~13k tests/Mpop.

Lots of large developed nations have the US beat by quite a bit, in fact. And
Iceland is literally a full order of magnitude higher!

In fact US testing policy has been largely a disaster. It's not the only
disaster, but this is an area (large scale PCR laboratory work) where the US
is _supposed_ to be good at stuff. And yet there's been almost no attention
paid to the problem at the highest levels of government.

~~~
losvedir
Oh, wow, that was my mistake. Thanks. I was getting the data from here [0],
which for me had a lot of countries selected but not all of them. I didn't
realize that it did not include by default a number of countries. When I
include them all I see that the U.S. is in the middle of the pack.

[0] [https://ourworldindata.org/grapher/full-list-cumulative-
tota...](https://ourworldindata.org/grapher/full-list-cumulative-total-tests-
per-thousand)

------
pmoriarty
This was covered about a month ago in episode 595 of _This Week in Virology_
[1], in answer to a listener question:

Rich Condit: _Garrett writes: The CDC guidelines are to test hospitalized
patients and symptomatic health care workers first, and the symptomatic
general public last. This seems backwards to me._

Alan Dove: _Yeah. I just had this conversation with my wife after she had
some, I mentioned this before, she had some coughing and shortness of breath,
got immediately sent to the ER in the hospital where she works, and they did a
chest x-ray, it was clear, and they said, "Ok, you don't meet criteria for
testing. Go back to work." And she's been fine since then, and she, we were
talking about it and she said, "Well, isn't that exactly who they should test,
because then I could go and infect patients?" and I said, "Well, if they had
enough tests, yes. But if you expand the testing to the people who are less
sick, you don't have enough tests. Whereas if you restrict the testing to the
people who are sickest, you do have enough tests." So it's a.. it's not the
right way to do it, but it's the way that you actually can do it._

Vincent Racaniello: _Yeah, we 're in this position because we don't have
enough tests. We didn't ramp up..._

Dove: _Because we don 't have enough tests. We didn't prepare fast enough._

Racaniello: _If we had, we could test a lot of people and get an idea of how
many actual infections there were, which would be very useful. But... we can
't. So we're stuck with this current policy._

[1]-
[http://www.microbe.tv/twiv/twiv-595/](http://www.microbe.tv/twiv/twiv-595/)
about 1 hour and 19 minutes in to the program

~~~
RandallBrown
But why test the people with the worst symptoms?

People with bad symptoms aren't the one's going out into the world spreading
the virus and the difference in treatment between a Covid and non-Covid
patient (from what I've heard) is minimal.

~~~
rovolo
A) You'll know which communities have infections. Many places are saying:
"it's not bad here, why should we isolate?"

B) If you know that someone with bad symptoms has the virus, then you can go
test everyone they contacted. You'll find more people who currently have mild
or no symptoms.

------
lokar
This seems to ignore the importance of testing symptomatic people to rule out
COVID (the most common outcome) so care givers can stop wasting PPE (which is
is short supply).

~~~
empath75
During a pandemic, it's more likely than not that any negative test on a
symptomatic person is false.

It's also quite likely that a positive test on an asymptomatic person is also
false -- depending on how prevalent it is in the general population.

~~~
dragonwriter
> During a pandemic, it's more likely than not that any negative test on a
> symptomatic person is false.

I don't think we've reached the point where COVID-19 is the leading cause of
fever, much less GI symptoms, so unless you define “symptomatic” extremely
narrowly (like, “in need of a ventilator”) that's probably not true in this
pandemic at this time in the US.

------
awinter-py
sampling bias debate reminds me of this stats legend from ww2:

the USAF wanted to armor planes where the bullet holes were. statistician abe
wald recommended armoring where the bullet holes _weren 't_ on the theory that
those were the non-survivable hits

can't interpret a statistic until you think about what's excluded from the
sample

~~~
pirocks
When I first heard this story it was the RAF not the USAF. I somewhat doubt
how true it was.

~~~
awinter-py
yup, 'stats legend', not history

there's an american math society article about this -- it evaluates the fun
version of the story in the context of wald's actual paper and a journal entry
by another scientist named wallis

------
vikramkr
The article mentioned using bar-coding to run pooled tests - that sounds
really interesting. Anyone know if there's a link to a paper on that? The
article doesn't link to anything on that unfortunately but that sounds really
interesting. I'm trying to visualize how that works with qpcr, where the
barcode is attached and where the primers bind (and presuambly after
amplification you sanger them to read the barcode?).

~~~
jamessb
Here's one preprint:
[https://docs.google.com/document/d/1kP2w_uTMSep2UxTCOnUhh1TM...](https://docs.google.com/document/d/1kP2w_uTMSep2UxTCOnUhh1TMCjWvHEY0sUUpkJHPYV4/edit)

("A Massively Parallel COVID-19 Diagnostic Assay for Simultaneous Testing of
19200 Patient Samples")

I think Figure 1b is the diagram you want.

~~~
vikramkr
Awesome! Thanks for finding that. So they do give up the extra specificity
from the reverse primer by having it be a constant region in the barcode, I
guess having a sanger step makes up for that a bit though since you can read
what it ligated to past the barcode and see if it's a SARS-COV-2 fragment, but
that does slow down getting the results. Like a truck of hard drives barreling
down a street versus sending data over fiber. Get a lot of reads in giant
batches or get less reads but with less latency.

------
dragonwriter
No, we need to test everybody, so we can't be testing the wrong people (the
reason we need to test sick people is different than the reasons we need to
test other people, but they all need tested.)

But we don't have nearly enough testing capacity (either tests or the
organized infrastructure to administer them, though both problems are being
worked on) to meaningfully test the general population, whether or not we
focussed our entire effort on the most important subset for reopening, so it
would be extraordinarily stupidly premature to shift our current testing
priority in that direction. This also means that general reopening is, _a
fortiori_ , extraordinarily stupidly premature.

~~~
jeremyjh
The article explained its reasoning. Maybe you could explain yours.
Specifically what is the value of testing very sick people when it cannot
affect the treatment plan ?

------
ctoth
Maybe someone here can explain to me how this is supposed to work. Let's
assume we have enough tests in the US to test every single person in the
country every 3 days, and are contact tracing everyone with a smartphone, and
providing smartphones to everyone without.

Now, with all this in place, isn't the best we can do to alert people _after_
they have already been exposed to the virus?

It feels a bit like the safe sex crusaders switching to say everybody can have
unprotected sex now, we'll let you know if you catch something, hopefully
before you infect your next partner. Which I suppose is more reasonable for
the group, but ... as the individual who is expected to actually go out in the
world to consume or whatever, this doesn't feel like a viable solution. What
am I missing?

~~~
heraclius
The target is to ensure that each case infects no more than one additional
person (‘R<1’).

Each infected person will come into contact with some other people. Testing
allows three things—

\- first, we can tell this person to stay at home and so stop them from
infecting more people;

\- second, we can tell the people they have seen to stay at home with good
contact-tracing, so that even if they get it they don’t spread it further; and

\- third, with enough tests and contact tracing, those who were exposed but
not infected don’t have to stay at home.

We are winning so long as R<1, even if there is some chance the infection
spreads; we do not need R=0.

The other way of reducing R requiring much less testing and contact tracing is
a lockdown. This has obvious downsides. The point of a programme of testing
and conyact tracing is that we can turn the cost of avoiding disaster from a
lockdown to sticking some things up people’s noses.

edit: typo in first para

~~~
ctoth
So I guess I'm still not seeing this. Can you give me a concrete idea of what
this looks like? Let's assume that it is the middle of August and the food
situation is still somehow stable, I install my contact tracing app, I get a
clean test. Then what? If we miss one person, that one person can still infect
an entire office building by coughing in an elevator. Because of the two week
incubation period, those people will not know they're infected until at least
a couple of days in, even assuming testing daily. We don't yet know how long a
person can infect before testing positive, but this amount of time is most
likely not 0. If this amount of time is less than 24 hours the person can
still make it anywhere in the US by air. If any longer they can make it
anywhere in the world. How do we not have constant low-level infection
everywhere?

~~~
jellicle
Since this is infectious before symptoms show up, it's basically impossible to
eliminate it entirely.

But suppose A starts showing symptoms, tests positive. We can immediately
notify B1, B2 and B3 that they need to quarantine, immediately. Before they
start showing symptoms. And therefore we're cutting down on the time that they
were infectious and spreading. Therefore generation C is only a couple of
people instead of dozens. We can notify C generation as well, immediately if
we wish. This causes a large quarantine - there are a lot of false positives
who are quarantining without being infected - but it would massively reduce
the spread. If you can immediately test all of generation B and C, you can
perhaps avoid some of the quarantining (assuming a negative is reliable).

Maybe contact tracing misses some, maybe some new infected come from other
countries, maybe some people don't quarantine when told. All these things keep
the infection going. But it can be held down to a manageable level.

~~~
user_50123890
Why would it be? China, South Korea, Hong Kong have all pretty much managed to
lower their amounts of new cases down to basically zero, and their society is
open for business albeit with social distancing and mandatory mask usage.

The trick is to NOT stop testing once your case count starts going down,
instead give the test to everybody that wants one.

A few million spent on 99.9% negative tests daily > a few billion spent on the
economy being shut off daily

------
bo1024
But the tests aren't perfect, so how to get actionable data from them isn't
clear. We saw this with the flawed west coast studies. If a test has false
positive or false negative rates even as high as 1%, and we run hundreds of
thousands to millions of tests per day...that's thousands or tens of thousands
wrongly quarantined for 14 days, and the same number who are contagious but
told it's okay to go out.

~~~
munificent
We are currently quarantining about 300 million here in the US, so tens of
thousands would be a massive improvement.

The way to think about this is: who do we need to test so we can start _un_
-quarantining people.

The goal is not to find out who has it because right now, we are essentially
behaving as if the entire US population is infected. The goal is to
efficiently determine who is very unlikely to have it so that those people can
start incrementally returning to normal life.

It's not worth testing symptomatic people: they've already "failed" one test
in that we at least know they have symptoms. Simply continue to treat them as
infected.

~~~
kd0amg
I'm pretty sure GP means actual quarantine. We are not quarantining hundreds
of millions. We are advising hundreds of millions to practice social
distancing.

~~~
Marsymars
Depends on the circumstances. I live alone and work from home, so there's very
little difference for me between the current situation and an indefinite
quarantine.

~~~
bo1024
For anyone who exercises daily, there's a really big difference!

~~~
Marsymars
On a continuum from my usual daily activities (gym for lifting, climbing,
ultimate, soccer) and my current activities (bodyweight exercises in my home
and runs around my neighbourhood), I’m much closer to indefinite quarantine
than I am to a normal state of affairs.

------
rapjr9
If the goal is to stop deaths and prevent economic damage, then what is the
alternative to testing (both for antibodies and for active presence of the
virus), assuming that testing everyone in the US multiple times in the near
term is not possible? Without testing a lot of people will not willingly
return to work, which is already hurting the economy. Without testing we don't
know the new places where the virus is spreading until a week or two later, so
reactionary measures like contact tracing don't work as well. Total lockdown
reduces deaths, but destroys the economy and reduces the scope of life.

Maybe we need to use the tools we already have, such as flu surveillance and
data from hospitals, to detect excess non-flu infections. We seem to be able
to do flu tests, are they more scalable so that at least flu can be ruled out
in many cases?

If widespread testing can not happen because we can't build factories to make
reagents/swabs/tubes/PCR array machines/etc. fast enough, we need to start
thinking of alternatives. We don't actually seem to understand yet how the
virus spreads, too many clinicians trained in handling infectious disease are
getting sick despite PPE. If the new small antibody test results are right,
then the virus is spreading much faster than can be accounted for via droplet
spread as the main mechanism; we may have to consider birds, mosquitoes,
surfaces, skin touching, and other methods as possible common spreading
mechanisms. If we understood transmission better then it might be possible to
tell people how to truly protect themselves, and then they could go back to
work. So understanding transmission better is something that could be used in
addition to whatever testing is available in order to prevent deaths and
economic damage. But people may not follow the new rules based on that
understanding, so get the social scientists involved to get the message
across. Get OSHA involved to set best practices for workplaces. It seems like
there is probably a lot that can be done, even without testing, and at present
we may have to assume testing will not be sufficient in the near term (3-6
months).

But someone has to start thinking about these things and doing them, and I'm
not seeing any evidence of this in the news. Given that contact tracing is not
already ramping up (I've seen only Massachusetts as having a plan to scale it
up but I tend to only see East Coast news) I have to wonder if anyone is even
thinking about alternatives to testing if testing at scale is not possible.

------
corny
Everyone has an opinion. The only opinions I am taking seriously right now are
from professional epidemiologists - not doctors, nurses, oncologists,
bioethicists, or economists. This article is just noise to me.

------
PeterStuer
"This type of voluntary contact tracing is labor-intensive and requires some
training, but it does not require highly specialized skills. Technology can
speed it up without risking a permanent erosion of privacy or the further
intrusion of for-profit firms into our personal lives."

This requires a huge leap of faith, which frankly, under surveillance
capitalism you would be a fool to accept at face value.

Austria developed such an app, but only 3% of people could be convinced to
install it which makes it completely useless even if it would have worked
(which I believe it would not for technical reasons).

