1. The current test is designed for the scenario that someone shows up to medical provider with symptoms. Test answers the question: are the symptoms caused by COVID-19?, quite reliably (negligible false positives, low false negatives).
2. The current test won't produce terribly useful data in someone without symptoms (either before, or after the illness). This is why for example certain well-known political figures saying they have been tested and cleared after potential exposure is not very meaningful.
Therefore ideas like: let's randomly test the population to see how much of this is out there, and I had what I think was COVID-19, I want to be tested to confirm, are not practical.
A test that can determine if someone was infected in the past is in development still.
If you want accurate numbers for statistics, including people who never had symptoms, you can do antibody testing on a random sample of population, that will indicate people who had the disease - but that's kind of too late for that particular location and those particular patients, that's for epidemiological studies and helping other locations. I recall reading about one such study for Covid, but I don't remember which country did it.
What kind of testing they do in those situations?
I'm glad you're better. Please be careful going forward, though. You shouldn't assume you have an immunity unless you have a positive test result.
Even with the strict pre-test screening that focus strictly on high probability patients, some locations are reporting very high (90%) negative test results from assumed cases.
It's best to continue practicing safety cautions as if you did not have a COVID-19 infection
People don't talk about it much yet, but we really need an immunity test to determine if someone has antibodies.
Vaccines are all about tricking our immune system into preparing those specific antibodies before an infection occurs, so it can stop it quickly. If reinfection is true, what does that say about the nature of this virus and how difficult it is to create a vaccine? Are there other viruses that reinfect like this?
If true, it would go against all priors for how humans build immunity to viruses - especially coronavirus (common cold).
There may be a time limit to immunity, but having none at all after recovery would be rare indeed.
Without significant evidence (more than one somewhat anecdotal case of re-emergence), there's little reason to assume the body doesn't "remember" the virus after recovery with antibodies.
Seems like unnecessary FUD to spread that idea around without more evidence.
Remember, coronavirus are ~25% of colds. There are many other families (like rhinovirues), that cause what we think of as the cold.
Another possible implication is that there could be multiple strains in circulation, not that the first strain wasn’t immunized against.
You are totally right that we need more evidence and this is very unlikely to be happening. But, I am trying to convince OP to continue to be cautious even if they appear to have recovered, both for themselves and for others. It seems reasonable to be cautious. People have presented apparent recovery only to go on to appear infected again.
I will continue self-quarantine for another couple weeks, and will definitely continue social-distancing measures etc. etc. after that.
https://cmmid.github.io/topics/covid19/severity/diamond_crui...
I dunno, maybe that's an indication that the fatality rate is lower than 1%. Or that dying takes longer than 14 days.
This is considered in the article I posted.
This gives them a higher median than the general population, but a lower density of the truly old. And deaths are strongly clustered among the truly old.
In the small Italian city of Nembro in Bergamo, 0.6% of their entire population has died in the last 12 days. That's 70 people in a small town of 11,000 — typically there are fewer than 70 deaths every six months. Now we're certainly _overestimating_ the denominator and still getting a number that's larger than the flu. While the numerator is also an overestimate (because it includes deaths not related to COVID-19), their healthcare system is stretched beyond capacity due to the virus leading to difficulties treating all illnesses and traumas.
https://www.washingtonpost.com/world/europe/coronavirus-obit...
[Nembro] Age Distribution (E 2019)
0-9 years 1,018
10-19 years 1,191
20-29 years 1,179
30-39 years 1,192
40-49 years 1,640
50-59 years 1,850
60-69 years 1,465
70-79 years 1,181
80+ years 810
https://www.citypopulation.de/en/italy/lombardia/bergamo/016...
Note that Florida is similarly 28% over 60.
On top of that, this is in a region of Italy where the healthcare capacity has been completely overwhelmed. That's going to be devastating for the prognosis of an older person who needs a ventilator.
https://translate.google.com/translate?hl=en&sl=it&u=https:/...
Since Feb 25 there have been 91 deaths with positive COVID-19 diagnoses. In total there have been 330 deaths. I'd be very curious what the age breakdowns are.
Anyhow, this was just a small example that shows that we're already seeing significant mortality relative to the _total population_ and not just by confirmed positive cases.
> Given the amount of testing being done in South Korea, we can rule out that there are a lot more people currently infected than we know about. And if there were a lot more people recovered than we know about, we would have seen deaths earlier in South Korea, since South Korea started their testing earlier. I suspect there's a lot more evidence that rules out the "fast and stealthy" hypothesis.
What we do know is that it can't be quite "there were zillions of people infected so when we talk about 1% IFR really it's 0.01% so everything is fine", because there are accumulating bodies in various localized places around the world. There's nothing we know to say that pattern wouldn't repeated everywhere.
It's also pretty well established that even in symptomatic cases where testing is widespread the disease has a multi-day incubation period.
That's a very strong claim. SK has done a lot of testing relative to most places but it's still:
a) A tiny amount relative to the population
b) Not a random sample of the population
Their tests were done at testing clinics that people had to take themselves to, which in many cases had large queues and generally you'd only go there if you actually felt really sick because otherwise why would you expose yourself to lots of probably really sick and infectious people?
So far there's overwhelming evidence that either a lot of people have the disease without symptoms, or the tests have a very high FP rate. There's also a lot of people writing like the person above, who are sure they've had the disease based on symptoms but were never tested. South Korea wasn't deploying their tests on people who were asymptomatic, they are doing the same as everyone else: testing people who present for testing or who otherwise seem to need it.
Our current evidence points to there not being millions of asymptomatic people.
This is strong evidence of asymptomatic circulation.
This conclusion is not in contradiction to the evidence behind your previous comment. In mid-February with ~60k confirmed cases that would be 300-600k asymptomatic ones. Which means that China did not have millions of asymptomatic people at the time. And so it is no surprise that a broad testing regime failed to find what did not exist at that time.
However what it also means is that as the number of confirmed cases skyrockets, it WILL be true (and possibly already is) that the number of asymptomatic cases will be in the millions.
Also from the article and the same Science paper, For every confirmed case of COVID-19, there are likely another five to 10 people with undetected infections.
https://science.sciencemag.org/content/early/2020/03/13/scie...
”We estimate 86% of all infections were undocumented (95% CI: [82%–90%]) prior to 23 January 2020 travel restrictions.”
But the phrase remains a common idiom. And in an internet discussion like this, the rationale that makes it bad form in poker does not apply. I cannot see anyone's reactions until after my action is complete and I hit "reply". And therefore I cannot gain a read and final decision based on my incomplete first stage of the action.
Though the bigger reason for not allowing it, is that it can really add confusion and slow down the game when a person says call and the next person now has to wait until they’re sure the current asshole isn’t going to say ‘and raise’ before they can act.
Oh, and keep in mind that poker is full of assholes who will do all kinds of anti social behavior to gain an edge. So the fact that this is a standard rule really gives some idea as to just how annoying it is to the poker community.
There's going to be some very interesting population studies done post-pandemic to determine exactly what percentage of people had asymptomatic cases (and thus could have unknowingly been contributing to the spread).
That's the necessary data to know when we can start rolling back the extreme measures being taken to slow the spread.
We need a measure to detect herd immunity
https://www.technologyreview.com/s/615379/antibody-test-how-...
Is that really the case? I'm finding it to be pretty common knowledge that "confirmed cases" is simply just that.
Furthermore, when you see that (larger) number it has a psychological effect of "this might be serious".
After making them think about incubation times that starts changing, but it takes a conversation.
What is common knowledge depends very much on who you're common with.
It's hard to convince people to sacrifice so much when they look outside their windows and see nothing special, plus read the news and find that some bomb/earth quake/accident somewhere killed more people in a day than the corona virus in a month.
Shouldn't the test detect antibodies that your immune system has developed?
The current testing that's reported in the media is an antigen tests, that directly tests for the presence of the virus. Once your viral load comes down, you will test negative for the virus. Hence the reason people are declared recovered after having two negative tests in a row.
A test for the presence of antibodies is a serology test. The last time I looked into it (~one week ago), serology tests were under active development, but had not been deployed anywhere in a widespread way.
So, right now the testing will only tell you if you currently have the virus. Coming relatively soon are tests that will tell you if you previously had the virus.
Conversely, there are probably genotypes running around today that are completely asymptomatic to Covid. You could have whole families shedding virus wherever they go and never even know what they’ve done.
And one of the ways we learn about immunology is to study people who are immune or asymptomatic, so it’s not just about quarantining people that we need to identify infected individuals.
Quick recombination so that a beneficial gene can spread without losing genetic diversity of the population is is one of the benefits of sexual reproduction. And immune resistance to new threats is one of the top reasons why we need this capability.
In fact we broadcast signatures of our immune systems in pheromones and women are attracted to the smell of men whose immune systems are different from their own. This improves the probability that the children will be resistant to a wider range of possible diseases.
https://en.wikipedia.org/wiki/Body_odour_and_sexual_attracti... is one of many places that you can start learning more about this topic.
It's not just highly likely, it's absolutely certain. I recommend the recent Khan academy video on this if you want to understand the math and you want a healthy dose of panic:
The two best data points we have would be South Korea and the Diamond Princess cruise ship. Both of these groups have high rates of testing and both have had enough time that we can know how the most of the cases played out, and in both cases we see the death rate at about 1%. This doesn't take into account possibly different age group distributions. The cruise ship probably has less children and less 80+ people than on typical distributions.
Additionally both the Diamond Princess and South Korea cases assume ready access to medical treatment. If the medical system is overwhelmed we will see much higher CFR due to critical cases not receiving adequate care.
UK authorities presented this exact number at their press conference last week.
I know of one that’s in the works https://www.sciencemag.org/news/2020/02/singapore-claims-fir...
I have seen other talk about such tests on Twitter but it’s too difficult to find it now.
Such tests seem to be called antibody tests or serological tests/assays.
EDIT: this twitter thread discusses such tests https://twitter.com/nachristakis/status/1240689935557865472?...
There are also some commercial antibody tests, which have some error rate and as all antibody tests can identify the virus after 7-10 days after onset of symptoms.
https://www.ndr.de/nachrichten/info/15-Coronavirus-Update-In...
I wish this was reflected more in the numbers being presented by various authorities. There is just too much confidence that confirmed cases are representative of the spread of the virus.
This unknown denominator can change mortality rate, and severe case rate by orders of magnitude.
Because of the dearth of testing in the US, it seems highly likely that far more people are infected, and maybe even recovered.
I'm fairly certain I've just recovered from COVID-19 given my symptoms, but can't get tested here in Colorado. By the time I am able to get tested it seems likely that I won't be shedding the virus any longer, and will test negative.
This article captures my feelings on this very well: https://blog.longnow.org/02020/03/14/an-epidemic-of-false-co...