Most Grand Princess passengers not tested

They solved for the equilibrium:

Despite assurances from Vice President Mike Pence that all Grand Princess cruise ship passengers quarantined at Travis Air Force Base would be tested for COVID-19, The Chronicle has learned that two-thirds of them have declined, often at the encouragement of federal health officials.

As of Wednesday, 568 of the 858 passengers screened while confined turned down the test, a federal official familiar with the Travis quarantine and testing told The Chronicle. The low testing numbers align with what passengers were told by officials during a Tuesday afternoon teleconference, citing a 30% acceptance rate for the novel coronavirus test, several passengers told The Chronicle.

“These folks know they are in a 14-day quarantine, if they test positive they are further delayed until they test negative,” said the official, who The Chronicle agreed not to name because they were not authorized to speak to the media, in accordance with the paper’s ethics policy. “They don’t want to stay. They want to be released.”

Interpret the resulting data accordingly, of course.  Here is the full story, via Anecdotal.

Comments

To be fair, if they were quarantined for 14 days, then there is 0 chance that they'll have the virus afterwards. Although it would be nice if they *did* get tested; cruise ships make for effective natural experiments in determining how this virus works.

otoh
if they were "quarantined" for 14 days in contact with infected and untested cruise ship passengers they might have a bigly chance of contracting coronavirus

Exactly. Each time they withdraw a group of people due to showing symptoms/failing the test, they have to reset the 14 day clock.

The quarantine has to be 14 days with no symptoms from anyone in the remaining group, without being potentially exposed to the virus.

In fact, if the virus can survive on surfaces for 24 hours, then it is 15 days without any of the remaining passengers showing any symptoms.

Quarantined doesn’t mean all in a big room mingling freely. They’re in their cabins. On the diamond Princess only 20% ended up infected, most of them crew members.

otoh
did you see the photo accompanying the article.
they were in a big room mingling freely and the article
mentioned long meal lines

Ok, that’s not like the Diamond Princess quarantine. Not the best way.

That is, the best way to spread covid-19 as widely as possible among a group of people, many of whom will not be tested before release.

14 days catches 88% of those who are exposed. 12% don't show symptoms until after 14 days. After 21 days you'll catch 98%.

All that's assuming that NO ONE in the quarantine turns positive during that 14 days.

Just rechecked the source of the numbers above - it's from a large series of child cases, not adults. So if there are only adults on the ship, then it doesn't apply.

Leaving aside the previous comment pointing out the giant hole, there is this research to consider. annals.org/aim/fullarticle/2762808/incubation-period-coronavirus-disease-2019-covid-19-from-publicly-reported

'There were 181 confirmed cases with identifiable exposure and symptom onset windows to estimate the incubation period of COVID-19. The median incubation period was estimated to be 5.1 days (95% CI, 4.5 to 5.8 days), and 97.5% of those who develop symptoms will do so within 11.5 days (CI, 8.2 to 15.6 days) of infection. These estimates imply that, under conservative assumptions, 101 out of every 10 000 cases (99th percentile, 482) will develop symptoms after 14 days of active monitoring or quarantine.'

That is 1%. Testing is critical to ensure the proper response to infection to stop spreading.

It's higher than 1%.
Some going into quarantine were - by what the stats show - asymptomatic or low-symptom. These then infect others on day 1 or 2 or 3... or 13, who then do the same to others. They then all leave the ship with fresh cases in their midst.
The go home and seed the country - the map looks like raisins in a loaf of raisin bread. You couldn't do a better job deliberately.

Yes, the very first picture of the article shows that this is an utter failure to practice a quarantine that will have any effect at stopping any spread.

Which is what one has come to expect from the American response, sadly.

In the quarantined village, Vo, (that is not V zero, but v oh) just outside Milan, population 3300, everyone was tested. Three percent, about 90 people, were found to be infected, more than half without symptoms. Two weeks later, everyone was tested again, and 10 more cases were found, again six without symptoms. Excellent report in the FT. The tests are essential. Why weren't they done?

"To be fair, if they were quarantined for 14 days,then there is 0 chance that they'll have the virus afterwards."

How do you figure that? If 858 passengers are "quarantined" for 14 days with, say, 10 of them initially infected, and complete mixing of the uninfected and infected, isn't it quite possible that many more than 10 will be infected at the end of 14 days?

See how easy it is to keep things looking peachy keen?

Until the virus has its say, that is.

Not necessarily. It could be being passed around the ship undetected. Someone could have contracted the virus yesterday.

Evidently people do not assign a value to free goods.

OR

The reason the market did not work was that they were not able to freely assign, at a market price, their right to a test,

OR

I don't want to know and I just want to get the F--- out of here.

In this thread Bill stumbles into the concept of revealed preferences.

I prefer to use conjoint analysis.

"I like the numbers being where they are,“ Trump said during a visit to the Centers for Disease Control and Prevention on Friday. "I don’t need to have the numbers double because of one ship that wasn’t our fault.“

Hand washing is far down on the list of critical public health measures. Testing is far and away the most important data driven way to reduce spread, by forcing those with the disease to not spread it through quarantining. This would seem to be obvious, and much like the utterly flawed Europe flight ban, shows why Trump needs to be thrown out of office.

Only five more years, moron. Hang in there!

Assuming he does not die from a covid-19 infection in the next 6 months. Hang in there.

If I thought I were being quarantined from the other passengers incompetently then I'd want to be released PDQ. So was this a measure of their distrust of their jailers?

I don't want to beat a dead horse, but this is consistent with a high false positive scenario. If you go 14 days without symptoms you really are golden. Why screw that up with a low confidence extension?

No, you are not golden, you are a 1 percenter. Testing is critical to prevent spread, it really is that simple.

"The paper found that, in a specific subset of those tested in China — asymptomatic contacts of known cases — the tests wrongly found them to be positive 47 percent of the time."

You do the math.

https://www.nytimes.com/2020/03/17/health/coronavirus-tests-who.html

Note also that if you have a 50 percent false positive rate, you rely on a "negative" that may also be false as your exit condition.

The tests in Korea are 95% accurate.

Use current data.

Grand Princess is mostly a story in the past, but I would indeed love to see current numbers, especially if they specify both false positive and negative .. breaking them out separately.

Are you confusing it with the Diamond Princess? Grand Princess passengers are all still in quarantine/treatment

> The tests in Korea are 95% accurate.

Likely not. False positives among commercial PCR tests routinely exceed 10% and that is among those likely to have the affliction that is being tested. And that is also among tests that have been on the market for years.

Let me save some of you 90 seconds if you dont read the link from Anonymous... directly before their pull quote, it says, the paper in question was "...referring to a study of an early diagnostic test used in China..." And directly after pull quote, "...But there have been no suggestions that the W.H.O. test, distributed worldwide, has such significant accuracy problems"

Yeah but, that was the *second* invocation of 50%. The first was from Dr. Deborah Birx, who said "“It doesn’t help to put out a test where 50 percent or 47 percent were false positives. Imagine what that would mean to the American people. Imagine what that would mean to tell someone they were positive when they weren’t.”

Dr. Deborah Birx, the White House’s coronavirus response coordinator

1% chance of showing symptoms, assuming they had it on day 1, and a lot of these people did not have it on day 1. Lots of these people never had it in the first place.

If we catch 99% of cases, what kind of R₀ are we looking at?

What is going on at Travis is not a quarantine, it is instead a way to further spread covid-19, particularly if people are not being tested before release.

Does this mean that the true mortality rate is even lower than the age-adjusted 0.7% I've been using until now (based on 7 deaths and 700 cases)? At what point do we admit that this is just a bad flu?

When the healthcare system can handle it like a bad flu.

Uh, mate .7% is, while not civilization ending, way, way worse than 'a bad flu'. The .1% number people have thrown around for the flu only applies to bad flu seasons. A lot of them are much lower.

0.7% certainly hasn't been the experience of Italy.
Best to wait until the battle is over before counting the casualties.

Italy's case numbers are total bullshit. There are a million cases but no testing.

South Korea confirms sub 1% mortality, even without universal testing.

YOU WILL PANIC WHEN CNN TELLS YOU TO PANIC, SOLDIER!!!!!!

Wuhan Flu Over The Cuckoo's Nest.

Just like the annual flu mortality stats (20,000 to 30,000), when the dust settles (and it will) they'll have an actual, China-Virus body count. And, just like the usual, annual flu, they will not have an accurate/real count of total persons infected/sick.

If you are not afflicted by a pre-existing medical problem, your odds of dying from the Wuhan Flu is in the magnitude of one-in-1,000.

Silver lining: if one acts there will be huge stock market profits from these depressed levels.

Apocalypse No!

+1. This confirms that the mortality rate among a population of old passengers is less than 1%, maybe 0.5%. This is very reassuring.

Now I am ready to bet my money that the number of deaths due to this coronavirus this year in the US will be less than 300,000.

Is there a prediction market in coronavirus?

Not on PredictIt, nor on Betfair.
They are the only two prediction markets I know.

Too bad. There would be a lot of interesting bets to make on the coronavirus, more interesting that questions like "How many tweets will Trump write this week?" that you have on PredictIt.

Less than 300,000 is a huge range.

We don't have NCAA office pools this year. Let's have a Wuhan Flu Dead Pool @ $10 a pick.

I want 79,998.

Closest not over wins.

Deaths in the US will be less than 100,000. Probably far less.

Now I am ready to bet my money that the number of deaths due to this coronavirus this year in the US will be less than 300,000.

I've already got a public bet with David Henderson at Econlog that U.S. deaths this year will be less than 40,000:

https://www.econlib.org/my-bet-on-covid-19-and-why-i-might-lose/#comment-242729

P.S. I'm thinking about asking him to renegotiate, with terms more favorable to him (i.e., something much lower than 40,000). :-) (But I need a few more days' review of trends.)

Interesting. Less than 40,000 seems rather optimistic. What is your thinking? I would be tempted the take that bet against you, but I don't like bets in that direction: I don't want to be in a position where I wish that more people die.

I'd wait three days.

a federal official familiar with the Travis quarantine . No name, anonymous sourcing.

The Chronicle has learned that two-thirds of them have declined, often at the encouragement of federal health officials.

Why would federal health officials encourage them not to be tested?

Say it together "false positives"

(or low test confidence in general)

False positives are not a problem in any data driven health care system. since it only extends the period of isolation, no more, no less - particularly assuming more accurate testing can be brought on line promptly.

Say it together "false positives"

(or low test confidence in general)

But regardless of what the federal health officials personally think of the test, I don't understand why federal *health* officials would encourage anyone in quarantine not to be tested. Even if they have concerns about false positives (which is probably silly from a math standpoint), from a public *health* standpoint, I don't see why a *health* official would encourage someone not to get tested. A false positive is much, much, much better from a public *health* standpoint than to release an infected person from a quarantine (or more properly "quarantine") situation.

Precisely - stopping spread is the entire reason for the quarantine in the first place, and allowing infected people into the community is the very first thing to be prevented.

What rate of false positive did you imagine when you said "silly from a math standpoint?"

“It doesn’t help to put out a test where 50 percent or 47 percent were false positives. Imagine what that would mean to the American people. Imagine what that would mean to tell someone they were positive when they weren’t.”

https://www.nytimes.com/2020/03/17/health/coronavirus-tests-who.html

Telling someone they are positive when they aren't means nothing but a longer period of isolation. Letting someone who has not been tested but has been exposed to covid-19 (welcome to Travis, it appears) out without testing means an increased risk of spread.

This is starting to get weird - testing is not for the individual, it is for the community.

I am going to shut down my computer now, so that I can reorganize my office as a social distancing distraction, but please, please, think these things through.

If you have been working and circulating in your community, and you get a false positive, how many people must quarantine?

This discussion is about a covid-19 quarantine of curise ship passengers that is not only not a quarantine, but a way to increase the virus spreading.

This is an incredible blunder.

They kept the cruise passengers for 14 days. assuming reasonable precautions, with or without the test they are now safe for release.

But think again about the early bad tests. Say you test your entire population. You get 50% false positives, which is half the population. So you isolate them and then all their contacts. You just isolated the whole population.

*That's* why wide testing with high false positive is useless.

Note, not exactly "half the population." Moving too fast.

"The false positive rate is calculated as the ratio between the number of negative events wrongly categorized as positive (false positives) and the total number of actual negative events (regardless of classification)."

But as a close approximation ..

"I am going to shut down my computer now, so that I can reorganize my office as a social distancing distraction, but please, please, think these things through."

No, *you* think these through. (No wonder you post anonymously.)

These were people on the Diamond Princess cruise ship who went straight from that hell to Travis Air Force Base. The only result of them testing positive--even if it's a false positive--will be more time for them in quarantine.

If you have been working and circulating in your community, and you get a false positive, how many people must quarantine?

They haven't been "working and circulating" in the community. They were about the Diamond Princess cruise ship, and went straight to Travis Air Force Base. Try reading and thinking before you comment.

The cruise ship is a teaching moment for why the tests weren't pushed there and everywhere.

It's a complex question when you can't trust your own test.

It's a complex question when you can't trust your own test.

Nobody but you thinks the tests that could and should have been run on Grand Princess passengers at Travis Air Base would have been inaccurate.

Once again, I don't see any possible justification for why the federal *health* officials would encourage the quarantined Grand Princess passengers not to get tested. They should have been begging the passengers to get tested.

> means nothing but a longer period of isolation

No. False positives consume resources from the medical community. It consumes their time, it consumes their tests, it consumes their protective equipment. All of which are in extremely short supply in the beginning.

Note also that this is exit *after* 14 days. I think everyone is pretty sure that in that time you are recovered, or never had it.

This is starting to get really weird - without testing, you have no idea if someone was infected on day 11 of that 14 day quarantine, as the actual quarantine appears to be nothing but a giant covid-19 mixing bowl.

That is a separate separation issue.

We know that people who are infected have false negatives for long periods, likely while they are also contagious.

So again regardless of the test you have to have good procedures.

Note also-also that if you don't have high confidence and high availability in your test, you go to lockdown to achieve something like that 14 days in the general population.

Please stop spreading misinformation.

The tests as conducted are 95% accurate. They run multiple tests per sample to confirm.

How accurate is a 95% accurate test run 3 times per sample?

stop spreading misinformation

Listen nimrod, I post a story in the NY Times from 2 days ago.

You pull numbers (maybe accurate, maybe out of your ass, who knows) with no link.

Link it of go back to your cell.

do you have a reference for your claim about the testing "accuracy"?
screening tests are usually described in terms of sensitivity and specificity

"Dr. Michael Mina, an assistant professor of epidemiology at the Harvard School of Public Health, said both the W.H.O. test and the initial C.D.C. tests were “exceptional” in their accuracy."

https://www.nytimes.com/2020/03/17/health/coronavirus-tests-who.html

I think Mycroft would agree with me that "exceptional" is not a number, and certainly not "described in terms of sensitivity and specificity"

Oh that's a tough choice.

On the one hand I have the learned opinion of a professor of epidemiology from the Harvard School of Public Health calling it "exceptional"

And on the other hand, I've got anonymous the internet troll who says "exceptional" is not a number.

Well darn, that's a really tough choice. Hmmm, who's opinion should I lean towards. Dr. Michael Mina or 'anonymous'? Assistant professor of epidemiology or a retired guy who likes to take hikes? Harvard School of Public Health or guy who doesn't read his own links?

I'm sorry but I just can't decide between the Expert in the Field and the internet poster who is always claiming we should follow the advice of the Experts (unless they contradict with his opinion).

You say you aren't a troll, but you sure play a troll game there.

I did *not* assume a value for "exceptional."

I have been talking about how the early bad tests shaped strategy.

anonymous is a troll. You'd be better off not responding to him.

And I'm surprised by the number of people who cannot wrap their heads around the fact that a 50% false positive rate is possible, and what it does to your planning.

Read the darn story.

I did read the NYT article you posted at the top. It completely contradicts your assertions. This is why I think your a troll. You routinely post to links that you obviously didn't actually read yourself.

Reference:

"Dr. Michael Mina, an assistant professor of epidemiology at the Harvard School of Public Health, said both the W.H.O. test and the initial C.D.C. tests were “exceptional” in their accuracy.

The problems with the C.D.C. test have been attributed to flaws in the manufacturing of reagents for kits, not in the C.D.C.’s design."

https://www.nytimes.com/2020/03/17/health/coronavirus-tests-who.html

Now you are playing games with the timeline, and the available data.

In the early days 47% false positives happened. The link doesn't contradict that, it documents it. And it documents that US leaders knew that, and understood the significance.

It moves from there to a claim that newer tests are "exceptional."

That's great, and I hope they are, but "exceptional" is not a number.

It could be worse than that. '“exceptional” in their accuracy' could mean exceptionally bad. It's true that it would mean that only in the mouth of a politician or lawyer; or at least so I hope.

And again:

Instead of using the WHO protocol, the CDC decided to create its own test using three different genes from the German test. That’s not an entirely unusual decision — the agency also created its own test during the Ebola outbreak in West Africa in 2015. But when some state labs tried to validate the test, it appeared to cause false positive results. The agency had to redesign and remanufacture test kits, which contributed to the delays in getting widespread testing up and running.

Blame that on "reagents" if you will, but it is exactly about false positives as the reason the CDC test could not scale!

https://www.theverge.com/2020/3/17/21184015/coronavirus-testing-pcr-diagnostic-point-of-care-cdc-techonology

interesting that the newyorktimes.com previously said that not getting the test from the w.h.o. was a bigly mistake by the cdc but now the newyorktimes.com says the w.h.o. test was never available or offered to the cdc !

@#$%! Take a look at that picture at the head of the story:

It should be titled, "How not to quarantine people."

But I guess the caption does say it all: "People under quarantine at Travis Air Force Base wander through the facility. Robert Archer, who is there with his wife, said the common areas get very crowded and long lines form for meals."

I guess Gregory House would add: "Idiots!"

Yep, this is the sort of scene that also played out in American airports after the European flight ban.

Not a problem, move along seems to be a standard MR commentor response when witnessing such utter failures.

Use your handle prior_clockwork, you were adamant it wasn’t banned.

There were 360 symptomatic patients on board, accounting for 52% of al those discovered to be carrying the virus. That is, just over 11% of the passengers and crew were actually ill.

Let’s remember that for the Diamond Princess, only 20 % were infected and that’s with the passengers not initially quarantined and mingling freely. The virus doesn’t spread all that easily. The incubation period has a distribution with a mean of 5 days. 14 days is at the extreme end.
Quarantine for 14 days and test at exit should be safe.

They are not testing at exit it seems, and people are just mingling and hoping to be released. “These folks know they are in a 14-day quarantine, if they test positive they are further delayed until they test negative,” said the official, who The Chronicle agreed not to name because they were not authorized to speak to the media, in accordance with the paper’s ethics policy. “They don’t want to stay. They want to be released.”

An incredible blunder if true.

Mingling is nuts. It's like whoever is in charge of this doesn't want to be in charge of it.

One company I know that requires people on-site broke their employees into "Team A" and "Team B" and only 1 group is allowed on-site at a time, because they don't want to have all their employees sick at once if something breaks out.

"Let’s remember that for the Diamond Princess, only 20 % were infected "

Interesting that you'd know that, since the whole point of the article was to inform us that they were not tested.

This article is about the Grand Princess!
The Diamond Princess is a different ship that was docked and quarantined in Yokohama, Japan. As far as I know everyone on that ship was tested!

You are correct I'm wrong.

"Bbbbbut we knnnnow that they just didn't get it because they were quarantined....! It's not possible it's just not that virulent (because immunity or weak symptomatic cases)" - Chumps.

That's one of the things I've been noting. A high number of false positives in early test inflates the number of "asymptomatic patients." It also inflates virulence.

But it has the reverse effect on the fatality rate. If there were fewer cases, a higher percentage of them actually died.

If tests are inaccurate, some of the dead might be false positives too.

I don't understand Tyler's point.

1) What is the equilibrium to be solved?

2) What is the solution to this equilibrium?

3) Why did the federal health officials encourage the passengers to avoid the test?

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