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Old 04-05-2020, 03:17 PM
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Asymptomatic infection rates


Over the next few weeks we should getting some data that in aggregate will give us a better sense of how many have actually been infected but never even sick enough to think of it, let alone officially diagnosed, in areas that are beginning to approach their peaks. It is a subject that deserves its own thread as the data comes in, both to share the data and to discuss its implications.

The CDC is starting to do some seroprevalence studies.
Quote:
Joe Bresee, deputy incident manager for the CDC’s pandemic response, said the agency hopes to flesh out the portion of cases that have evaded detection using three related studies.

The first, which has already begun, will be looking at blood samples from people never diagnosed as a case in some of the nation’s Covid-19 hot spots, to see how widely the virus circulated. Later, a national survey, using samples from different parts of the country, will be conducted. A third will look at special populations — health care workers are a top priority — to see how widely the virus has spread within them. Bresee said the CDC hopes to start the national survey in the summer; he gave no timeline for the health workers study.

“We’re just starting to do testing and we’ll report out on these very quickly,” Bresee said at a media briefing. “We think the serum studies will be very important to understand what the true amount of infection is out in the community.” ...

... Getting a sense of how many mild and asymptomatic cases there are helps authorities plan for future responses to Covid-19 activity. If it’s known that a high percentage of people in a community were likely infected when the virus moved through during its first wave of infections, the response to a reappearance later might be tailored to protect only high-risk people, for instance. ...
It will be difficult to interpret though in the context of a curve that is not yet flat. Love to see it in China or South Korea
Germany is planning to do similar widespread seroprevalence testing, but not until the end of the month.
Quote:
At the end of April, health authorities also plan to roll out a large-scale antibody study, testing random samples of 100,000 people across Germany every week to gauge where immunity is building up.
The WHO is planning global studies.
Quote:
In an effort to understand how many people have been infected with the new coronavirus, the World Health Organization (WHO) is planning a coordinated study to test blood samples for the presence of antibodies to the virus. Called Solidarity II, the program, which will involve more than half a dozen countries around the globe, will launch in the coming days, says Maria Van Kerkhove, who is helping coordinate WHO’s COVID-19 response.

Knowing the true number of cases—including mild ones—will help pin down the prevalence and mortality rate of COVID-19 in different age groups. It will also help policymakers decide how long shutdowns and quarantines should last. “These are answers we need, and we need the right answers to drive policy,” WHO’s executive director for health emergencies, Michael Ryan, told a press briefing on 27 March.

Tests that detect the virus directly have already identified nearly 1 million cases of COVID-19 around the world. But because of test shortages, many cases, especially mild ones, have been missed. Antibody tests can help give a better sense of the virus’ true spread because they can also detect whether a person has been infected in the past, leaving them with antibodies that might protect against future infection. ...

... Solidarity II could be available within a few months, Van Kerkhove says, though the study is intended to run for 1 year or longer.

Several smaller antibody surveys now getting underway could yield early results within weeks. For instance, Jay Bhattacharya, a health policy expert at Stanford University, says next week he and his colleagues hope to test 5000 people in California’s Santa Clara county for antibodies. ...

... And on Tuesday, researchers at the University of Bonn launched an antibody study of 1000 people in the western German region of Heinsberg, the site of one of Germany’s largest outbreaks. (Many residents were apparently infected at a local carnival celebration in the village of Langbroich-Harzelt in late February.) Virologist Hendrik Streeck of Bonn’s University Hospital says he and his colleagues used WHO’s protocols to help shape their study. He says initial results could be announced as early as next week. ...
Meanwhile testing everyone in one town for the virus and active infection tells us something too. Interpret the following with the knowledge that we do not know if those who have asymptomatic to very mild infections shed for as long as those who are more seriously ill or if they stop shedding in a significantly shorter period of time. The latter makes sense but would just be a guess. In the isolated Italian of village Vo’Euganeo, population 3000, apparently, they actually tested nearly everyone. Italy so still skewing older, but more of a complete sample than the Diamond Princess. The majority who were positive were asymptomatic.
Quote:
the great majority of people infected with covid-19—50-75%—were asymptomatic
I cannot verify that those who were tested and asymptomatic were followed to verify they stayed such. And again we do not know how long asymptomatic and minimally symptomatic people test positive relative to those more ill. So interpret with caution and as part of a hopefully soon to emerge aggregate of information. But it is something.
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Old 04-05-2020, 03:36 PM
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Iceland looks to be a good source of information on this also.
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Old 04-05-2020, 03:43 PM
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It's possible that people who are asymptomatic are infectious for a similar period of time, but are not sneezing, coughing, or mouth breathing, so they shed a lot less virus.
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Old 04-05-2020, 03:55 PM
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As a person who believes I had a mild case several months ago, if I hear about any antibody studies, I will be more than happy to roll up my sleeve and give them some of my blood.
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Old 04-05-2020, 04:05 PM
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Seroprevelance? Are you just making up words?
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Old 04-05-2020, 04:11 PM
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Quote:
Originally Posted by MarMac83 View Post
Seroprevelance? Are you just making up words?
Seroprevalence
Quote:
Definition of seroprevalence

: the frequency of individuals in a population that have a particular element (such as antibodies to HIV) in their blood serum
First Known Use of seroprevalence

1977, in the meaning defined above
Just so you know, DSeid is a doctor and not in the habit of making up words.
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Old 04-05-2020, 04:17 PM
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Seroprevalence

Just so you know, DSeid is a doctor and not in the habit of making up words.
Well, it sounded good when I was typing it.
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Old 04-05-2020, 04:56 PM
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https://www.sciencealert.com/here-s-...thout-symptoms

Quote:
A World Health Organisation report about the coronavirus outbreak in China, published in February, found few instances in which a person who tested positive never showed any symptoms. Instead, most people who were asymptomatic on the date of their diagnosis (a relatively small group anyway) went on to develop symptoms later.

"The proportion of truly asymptomatic infections is unclear but appears to be relatively rare," the report authors wrote.

In the WHO study, 75 percent of people in China who were first classified as asymptomatic later developed symptoms, ProPublica reported. That means, technically, "presymptomatic transmission" is what's probably common.

Other research has reaffirmed these findings. A CDC study of coronavirus patients in a nursing home in Washington state's King County found that of 23 people who tested positive, only 10 showed symptoms on the day of their diagnosis. Ten people in the other group developed symptoms a week later.
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Old 04-05-2020, 05:20 PM
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No, seroprevalence is perfectly cromulent.
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Old 04-05-2020, 05:34 PM
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For how long were the "asymptomatic" describe above followed? Until we know this it's hard to say who is pre-symptomatic and who is truly asymptomatic.
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Old 04-05-2020, 05:37 PM
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Originally Posted by Dr_Paprika View Post
No, seroprevalence is perfectly cromulent.
And the seroprevalence rate of serum porcelain titers is still essentially zero.
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Old 04-05-2020, 05:38 PM
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For how long were the "asymptomatic" describe above followed? Until we know this it's hard to say who is pre-symptomatic and who is truly asymptomatic.
If they've had time to exhibit a measurable antibody response, I'd expect any symptoms that would manifest should have manifested by then.
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Old 04-05-2020, 05:39 PM
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That nursing home study really gives me pause as to how high the true asymptomatic rate might be in the general (younger and healthier) population. Those with positive test results averaged 80.7 years old and had serious health problems. They counted 23 as positive test results but are not counting two who had been transferred to a hospital before testing for COVID-19 symptoms, so let's use 25 as the better denominator. In THAT population 3/25, 12%, were asymptomatic and stayed asymptomatic. 12% of the highest risk group, sick disabled 80 year olds, had asymptomatic infections?! Wow.

From the ProPublica article your cite cites re China and true asymptomatic infections:
Quote:
“Most of the people who were thought to be asymptomatic aren’t truly asymptomatic,” said Van Kerkhove. “When we went back and interviewed them, most of them said, actually I didn’t feel well but I didn’t think it was an important thing to mention. I had a low-grade temperature, or aches, but I didn’t think that counted.”
One, we should take information form China in February about asymptomatic cases with several grains of salt, even if they involved the WHO. Two, from a practical POV those who developed symptoms that were so mild that they completely dismissed them are functionally in the same bucket.

Last edited by DSeid; 04-05-2020 at 05:41 PM.
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Old 04-05-2020, 06:19 PM
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If the symptoms were so mild that they were completely blown off and changed nothing, then there is almost certainly confirmation bias in asking about it after the fact after diagnosing an illness that has been constantly in the news.

The asymptotic rate must be higher than reported, even leaving out the paediatric populace, perhaps, portending problematic prevalence probabilities.

I suppose the distinguished Qadgop is referring to the China coronavirus? Or maybe the Corelle virus, or the Smith-Corona? Any one of those can leave you pyrextic.
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Last edited by Dr_Paprika; 04-05-2020 at 06:20 PM.
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Old 04-05-2020, 07:27 PM
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Originally Posted by Dr_Paprika View Post
If the symptoms were so mild that they were completely blown off and changed nothing, then there is almost certainly confirmation bias in asking about it after the fact after diagnosing an illness that has been constantly in the news.

The asymptotic rate must be higher than reported, even leaving out the paediatric populace, perhaps, portending problematic prevalence probabilities.

I suppose the distinguished Qadgop is referring to the China coronavirus? Or maybe the Corelle virus, or the Smith-Corona? Any one of those can leave you pyrextic.
Nitpick: I think you mean pyrexic.
Quote:
pyrexia - a rise in the temperature of the body; frequently a symptom of infection. febricity, febrility, fever, feverishness. symptom - (medicine) any sensation or change in bodily function that is experienced by a patient and is associated with a particular disease.
Adjective (comparative more pyrexic, superlative most pyrexic)
Learned a new crossword word.
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Old 04-05-2020, 08:17 PM
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No, that’s not what I meant.

“Forget it, Jake. It’s China-town.”
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Old 04-05-2020, 09:54 PM
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Was punning on pyretic, but yours works too.
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Old 04-05-2020, 10:05 PM
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At the height of their testing in SKorea, they found 30% of those testing positive, had no symptoms.
(Testing, protocols, data, all high quality for this particular location is a plus!)
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Old 04-05-2020, 10:43 PM
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At the height of their testing in SKorea, they found 30% of those testing positive, had no symptoms.
(Testing, protocols, data, all high quality for this particular location is a plus!)
Yes but in South korea, about 3% of cases end in death and 97% end in recovery. Thats still pretty bad. Granted I"m sure they're missing a lot of less clinical cases but thats one of the best tested nations out there and 3% of people still seem to die.
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Old 04-06-2020, 07:12 AM
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Was punning on pyretic, but yours works too.
I got what you meant! China, porcelain, pyrex, it is to laugh!

Last edited by Qadgop the Mercotan; 04-06-2020 at 07:13 AM.
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Old 04-07-2020, 09:24 AM
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Seroprevalence

Just so you know, DSeid is a doctor and not in the habit of making up words.
Well, we're NOT doctors, and he might be having some fun at our expense because we wouldn't be able to tell (actually I already knew seroprevalance to be a real word...)

I'm not in a hot spot, otherwise I'd love to volunteer for it. The friend (housemate) who brought back a bad cold from Philly and shared with me, in early January, is convinced that COVID is a real possibility because she truly felt wretched for several weeks, including a brief improvement before worsening. Me, not so much: my cold, while unpleasant, did not follow typical COVID symptoms. No fever, the cough was productive which I gather is not typical (maybe in an asthmatic it behaves differently?), and I didn't feel all that ill for all that long - just my sleep was disrupted from the coughing.

Not clear from the article: does the CDC plan to do followups on those whose blood lights up, to see if they are still showing antibodies a few months later?
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Old 04-07-2020, 09:40 AM
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How difficult would it be to do the antibody tests along with, um ... say a blood drive? Donate blood, get a free rapid Covid test, and do the antibody test on those testing negative?
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Old 04-07-2020, 04:36 PM
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How difficult would it be to do the antibody tests along with, um ... say a blood drive? Donate blood, get a free rapid Covid test, and do the antibody test on those testing negative?
It would be a reasonable sample of convenience but would risk not being representative of the general population.
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Old 04-09-2020, 04:27 AM
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Nevertheless that seems how some of the first studies will collect samples.

First in a hard hit town in Italy.
Quote:
When Avis volunteers summoned them for blood donation, they were confident that they would find a high number of Covid positives19. Confirmation has come from the results of tests and swabs: out of 60 citizens of Castiglione D'Adda, one of the municipalities in the former red area of ​​Lodi, 40 tested positive without knowing it. All asymptomatic, escaped from official statistics: they came into contact with the disease, they did not develop it ...
So among a fairly small self-selected sample of apparently healthy asymptomatic blood donors in a region of Italy that is near peak COVID-19 two thirds had had asymptomatic infections. Small and self-selected appropriately emphasized, some may have had the same thought process Mama Zappa shares, but still ...

Also apparently part of the U.S. planned approach.
Quote:
The first one, which will be funded by the National Institutes of Health, is already underway in six metropolitan regions in the U.S. It was started in Seattle when that outbreak happened, then New York City, then we quickly kicked in the San Francisco Bay area, and now we’ve added Los Angeles, Boston, and Minneapolis. Colleagues at regional blood centers are each saving 1000 samples from donors each month—often it’s just a few days each month—and they’re demographically defined so we know the age, the gender, and, most important, the zip code of the donor’s residence. Those 6000 samples, collected each month starting in March and for the next 5 months, will be assessed with an antibody testing algorithm, which we’re still finalizing, that will help us monitor how many people develop SARS-CoV-2 antibodies over time. That will show us when we’re going from, say, a half a percent to 2% of the donors having antibodies.

That will evolve into a national survey. With support from the U.S. Centers for Disease Control and Prevention [CDC], we’ll conduct three national, fully representative serosurveys of the U.S. population using the blood donors. That will be 50,000 donations in September and December of 2020 and November of 2021. We’re going to be estimating overall antibody prevalence to SARS-CoV-2 within each state, but also map it down within the states to regions and metropolitan urban areas, and look at the differences. ... We want to compare the results we’re getting from our blood donor serosurveys in several geographies with colleagues who are doing different types of populations surveys. We’re collaborating closely with colleagues at UCSF and the University of Washington, and they’re doing population serosurveys by neighborhood door knocking and capturing samples from the hematology lab. ... We’re cautious because blood donors are not a representative sample. ...

This also from that article which is consistent with the hypothesis that kids get so little identifiable or significant COVID-19 (and may be minimally contagious with it) because of their relative frequency and recency of multiple infections with the variety of other human coronaviruses that cause common colds.
Quote:
Q: What happens when SARS-CoV-2 infects a person who has antibodies to the other four coronaviruses that infect humans and cause the common cold?

A: We were on a call today with the CDC about this. If we look at people who just went through a SARS-CoV-2 infection and have a burst of antibodies against the virus, they’ve also boosted their pre-existing antibodies against the classic cold coronavirus. And the earliest antibody responses that CDC researchers have seen in careful longitudinal studies to SARS-CoV-2 are actually those cross-reactive memory responses to the classic cold coronaviruses.

Q: How might these cross-reactive antibody responses matter?

A: The immune memory to previous infections may help control infection with those cold viruses and even ameliorate symptoms of SARS-CoV-2 infection. ...
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Old 04-09-2020, 10:58 AM
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Anyones ideas on the thought that California' s (current) low infection fate is due to the virus passing through as early as Nov. 2019, and giving some degree of herd immunity?
Blood antibody testing started on 3200 people.

https://www.ksbw.com/article/new-stu...id-19/32073873

Last edited by Section Maker:Jupe; 04-09-2020 at 10:58 AM. Reason: typo
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Old 04-09-2020, 11:28 AM
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I would be completely unsurprised to read of a large number of Californians with evidence of past infection, perhaps asymptomatic or even labeled clinically as influenza or pneumonia not otherwise specified. I have no idea how antibody levels now can prove if that happened in March or in December.
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Old 04-09-2020, 11:40 AM
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A slight hijack, hopefully not too off-topic -- do they do these seroprevalence surveys for the flu? Once this is flattening out, will we be able to get good, apples-to-apples comparisons between how contagious SARS-COV-2 is compared to various flus.

My layman's impression is that it's much more contagious, but I've never seen this kind of coverage for flu outbreaks, so it may be confirmation bias.
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Old 04-09-2020, 11:56 AM
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They do them for sure but I don't know how regularly. There was a bunch of follow up seroprevalence surveys for H1N1, for instance. I would hope they're doing that extensively this year so we can muddle out what was flu and what was covid-19
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Old 04-09-2020, 12:03 PM
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I would be completely unsurprised to read of a large number of Californians with evidence of past infection, perhaps asymptomatic or even labeled clinically as influenza or pneumonia not otherwise specified. I have no idea how antibody levels now can prove if that happened in March or in December.
.

I had something in Nov, Dec where I was so shortwinded I couldn't even shop. 100 steps I was ready to keel over. Dry cough, nose clear but not aware of a fever or Muscle aches.
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Old 04-09-2020, 12:42 PM
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The IEEE has a nice layperson (well, layengineer) write-up on the testing methods and tests being rolled out for COVID-19, with links to detailed information on the who, what, where.

https://connect.ieee.org/Y0a0F0MUB00BQ0033PG0lHo

I am hoping the 5/13 minute tests for the virus are going to drastically increase the rate of testing for infection (the manufacturer claims 50,000 tests a day production rate).
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Old 04-09-2020, 12:56 PM
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As a person who believes I had a mild case several months ago, if I hear about any antibody studies, I will be more than happy to roll up my sleeve and give them some of my blood.
Same here. (Posting mainly to keep track of this thread)
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Old 04-09-2020, 01:50 PM
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And the seroprevalence rate of serum porcelain titers is still essentially zero.
Does that mean that it's never palindromic fibromyalgia?
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Old 04-09-2020, 02:13 PM
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Anyones ideas on the thought that California' s (current) low infection fate is due to the virus passing through as early as Nov. 2019, and giving some degree of herd immunity?
Blood antibody testing started on 3200 people.

https://www.ksbw.com/article/new-stu...id-19/32073873
”Herd immunity” requires a significant portion of the population (30% to 50% at least, depending upon the degree of infectiousness) to be immunized, either by vaccine or prior exposure. If 30% or more of the nearly 40 million population of California were infected, even assuming an asymptomatic rate of 80% would still be 8,000,000 people. If there is even only a 5% incidence of severe illness and net case fatality rate of 0.3% (which is about the low end of credible estimates) that would still be a net number of 400,000 new patients and 24,000 additional or premature deaths. If we saw an increase of severe acute respiratory distress across a period of three months that would have flagged epidemic surveillance systems as emergency rooms and ICUs registered an enormous unattributed spike in morbidity and mortality. And it isn’t as if California is walled off from the rest of the country. Los Angeles is a major tourist destination with Disneyland and Universal Studios being dense concentrations of crowds as well as a major transit center to international flights. The San Francisco Bay Area is obviously a major tech business hub with regular travel from and to China and other nations in Asia as well as domestic travel. Even without serology (which would not be able to tell you the timing of infections) it just doesn’t pass the smell test that the SARS-CoV-2 virus could have been circulating in North America undetected for several months before a sudden spike in severe illness and death.

In reality, given the apparent infectiousness of SARS-CoV-2, you’d probably need an immunity level exceeding 50% to get a really significant attenuation of spread, especially as it appears that the virus may be spreading by aerosol routes instead of just intimate contact or fomites (droplets on surface transferred hand-to-mouth). It should be noted that San Francisco instituted “shelter-in-place” protocols a week before California implemented its “Stay At Home” order which was the most vigorous isolation direction in the US to that date. California has also been significantly deficient in getting wide scale testing available even for highly symptomatic patients for reasons largely left for another forum. So, despite a certain...political imperative to attribute the lower rates of infection and death to “herd immunity”, it seems more likely to be a combination of a lack of good testing samples and the effectiveness of isolation measures. Which, of course, argues for maintaining a lockdown until the risks of overwhelming health systems is mitigated to reduce unnecessary death.

It should be noted that we are currently on the tail end of a flu season that slightly exceeded the pneumonia & influenza mortality threshold for an epidemic so any flu-like illness that was experienced in the Northern Hemisphere flu season of 2019-2020 was likely actually be the flu or some other endemic flu-like “common cold”.

Stranger
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Old 04-09-2020, 02:53 PM
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... It should be noted that we are currently on the tail end of a flu season that slightly exceeded the pneumonia & influenza mortality threshold for an epidemic so any flu-like illness that was experienced in the Northern Hemisphere flu season of 2019-2020 was likely actually be the flu or some other endemic flu-like “common cold”.

Stranger
EXCEPT that the unusual third hump occurred while lab confirmation of influenza went DOWN. (Same cite.) This can be seen specific to California even more so. https://www.cdph.ca.gov/Programs/CID...INALReport.pdf. Lab proven influenza admissions dropped while pneumonia admissions jumped really beginning in February. Interestingly California had a worse pneumonia year than usual and more so than the rest of the country seemed to have. It really does fit with COVID19 being there for while lost in the influenza statistics noise.

No estimates of infection fatality rate can “credible” without data on the rates of undocumented and unsuspected infections in the general population, inclusive of those asymptomatic and minimally symptomatic to the degree of barely noticing it. That is the data this thread is anxiously waiting for.
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Old 04-09-2020, 03:37 PM
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Originally Posted by DSeid View Post
EXCEPT that the unusual third hump occurred while lab confirmation of influenza went DOWN. (Same cite.) This can be seen specific to California even more so. https://www.cdph.ca.gov/Programs/CID...INALReport.pdf. Lab proven influenza admissions dropped while pneumonia admissions jumped really beginning in February. Interestingly California had a worse pneumonia year than usual and more so than the rest of the country seemed to have. It really does fit with COVID19 being there for while lost in the influenza statistics noise.
But that third hump starts in early March, which I would agree corresponds with the likely contagion of SARS-CoV-2 preceding the COVID-19 outbreak. The first peak appears in November and the second one peaking in late January/early February, which is consistent with previous trends (probably some relationship with students going back to school and passing viruses around). California has had an unusually cold and wet winter which it is still "enjoying" (I'm actually personally enjoying it but we usually have sunny warm weather by mid-February) so a higher incidence of pneumonia might be somewhat explained just by the environmental conditions even with a pathogen-specific outbreak. But I'll go back to the reality that if SARS-CoV-2 were really making the rounds back in early November, we'd be seeing a very significant quantity of unexplained ARDS patients (not just typical pneumonia presentations but aggressive respiratory failures in patients without previous explicable morbidity) and it just isn't there.

New York is often cited as a special case for transmission for how dense the population is and how much the population uses public transit, but while the Bay Area is not comparable in strict density or the quantity of people on public transit, it is still dense enough with open plan workspaces and people in public spaces where people are on top of one another that you'd expect to see more flareups prior to when the epidemic was formally recognized, which is why San Francisco issued the "Shelter In Place" order so early. We don't see any of that, and in fact the Bay Area has been remarkably quiet in terms of hospitalizations. For the virus spreading/herd immunity argument to make sense, the virus would have to have suddenly turned virulent, or a second much less virulent strain would have had to circulate first to provide immunity which was an early thesis but while several minor strains have emerged there isn't any evidence that any are significantly less virulent than others.

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No estimates of infection fatality rate can “credible” without data on the rates of undocumented and unsuspected infections in the general population, inclusive of those asymptomatic and minimally symptomatic to the degree of barely noticing it. That is the data this thread is anxiously waiting for.
Agreed, and that is why I picked 0.3% as a low end for the CFR. It could in fact be lower if the rate of asymptomatic cases is higher. However, from the best samples we have (primarily South Korea, but also some testing done in Germany, Iceland, and comprehensive testing of a town in Italy) the rate seems to be somewhere slightly above 1%. My totally off-the-cuff guestimate is that it'll come in lower once we have a statistically significant sample of antibody testing, and maybe low enough to justify the more optimistic estimates of total deaths that we're seeing but I wouldn't make any plans on reducing isolation measures until there is solid data in hand.

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Old 04-09-2020, 04:00 PM
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Originally Posted by Stranger On A Train
But I'll go back to the reality that if SARS-CoV-2 were really making the rounds back in early November, we'd be seeing a very significant quantity of unexplained ARDS patients (not just typical pneumonia presentations but aggressive respiratory failures in patients without previous explicable morbidity) and it just isn't there.
So what are the unexplained November ARDS numbers in California and what number would've been significant?
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Old 04-09-2020, 05:42 PM
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Thank you all for this discussion. Stranger On a Train I would note that Feb in California is one the wettest months of the year. Even for SoCal. Systems usually swing north by March/April, but the"normal" storm track has been screwed up now going back 15 years or so?
This year Feb was one of the driest on record.
As I type this its is 55f out and been raining all day (and week) in Santa Barbara. Interesting April..(before Gray may and June gloom)

edit to add:
Questions: Is seasonal flu temperature related? My laymans understanding was that since more people were in close contact due to being indoors, that the infection rates spike because of that. So basically the flue/colds/virus's are here year round?

Mutation rate? Is it continual? A simple answer or reference link would be great!! Thank you.

Last edited by Section Maker:Jupe; 04-09-2020 at 05:43 PM. Reason: forgot to ask
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Old 04-09-2020, 08:08 PM
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Originally Posted by Section Maker:Jupe View Post
Thank you all for this discussion. Stranger On a Train I would note that Feb in California is one the wettest months of the year. Even for SoCal. Systems usually swing north by March/April, but the"normal" storm track has been screwed up now going back 15 years or so?
This year Feb was one of the driest on record.
As I type this its is 55f out and been raining all day (and week) in Santa Barbara. Interesting April..(before Gray may and June gloom)

edit to add:
Questions: Is seasonal flu temperature related? My laymans understanding was that since more people were in close contact due to being indoors, that the infection rates spike because of that. So basically the flue/colds/virus's are here year round?

Mutation rate? Is it continual? A simple answer or reference link would be great!! Thank you.
Seasonal flu considered more humidity than temperature related is my understanding.

The best mutation tracker I've seen even if I don't quite understand it! Their narrative.
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Old 04-09-2020, 11:12 PM
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The Germany study in Heinsberg has released some early results (the study is not complete).

Translation available here: https://translate.google.com/transla...Xx6t2EHkjp-ap2

Quote:
How dangerous is the new virus? And how is it? Streeck, director of the Institute of Virology at the University of Bonn, was able to answer at least some of these questions with Laschet carefully before the end of the entire study period. The most important interim result: According to Streeck, the study shows that measures to contain the epidemic can be relaxed.
...
The infection rate is around 15 percent. This is an important number and will cause the spread to slow down, says Streeck. These first, but already scientifically representative interim results are a rather conservative calculation.
...
Immunity has been demonstrated in 14 percent of the residents of Gangelt, a municipality in the Heinsberg district. So far, it was only assumed that an existing illness protects against the virus, now this assumption can be proven.
...
The mortality rate , which is derived from the study results in Gangelt, is around 0.4 percent. Data from Johns Hopkins University, which records case numbers worldwide , shows that mortality in this area is five times higher. The study also concludes that strict hygiene regulations drastically reduce the risk of mortality.
15% of the population already infected and a 0.4% mortality rate seem quite favorable for the hypothesis that coronavirus is only moderately more deadly and a lot more contagious than the flu, and that the primary risk is not the mortality rate itself but the potential to overwhelm the healthcare system with an entire season's worth of illness in the space of a a few weeks.
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Old 04-10-2020, 12:23 AM
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I just went to the worldometer site and looked up the testing and infection numbers for the last two days (8th April to 10th April)

In that time, about 400,000 coronavirus tests were done in Germany, and 10,000 new cases of coronavirus were diagnosed.

So, right now, around 2.5% of people who get tested for coronavirus in Germany, turn out to have a positive test.

This doesn't seem to be compatible with the claim that 15% of the general population are infected. I don't think the district that this study took place in can be representative of the whole country
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Old 04-10-2020, 12:52 AM
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Correction to the above: I noticed that tests are updated less frequently than cases. Still, this cite says 50,000 tests per day being done in Germany, and new cases are going up by around 5,000 a day, meaning 10% of those tested have got coronavirus. It still doesn't make sense to me that people who are tested would have less prevalence of the disease than the general population.
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Old 04-10-2020, 01:07 AM
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That district is not representative, it was the site of one of the first outbreaks in Germany.
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Old 04-10-2020, 01:14 AM
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Ah, right. I misinterpreted your last paragraph

Yes, 0.4% seems not unreasonable - I think that's compatible with the death rate from South Korea where of course they've done rather a lot of testing (last I heard was about 0.6% ... but that probably doesn't count all of the truly asymptomatic people)
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Old 04-10-2020, 07:33 AM
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Quote:
Originally Posted by Absolute View Post
The Germany study in Heinsberg has released some early results (the study is not complete).

Translation available here: https://translate.google.com/transla...Xx6t2EHkjp-ap2


15% of the population already infected and a 0.4% mortality rate seem quite favorable for the hypothesis that coronavirus is only moderately more deadly and a lot more contagious than the flu, and that the primary risk is not the mortality rate itself but the potential to overwhelm the healthcare system with an entire season's worth of illness in the space of a a few weeks.
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Originally Posted by Aspidistra View Post
Correction to the above: I noticed that tests are updated less frequently than cases. Still, this cite says 50,000 tests per day being done in Germany, and new cases are going up by around 5,000 a day, meaning 10% of those tested have got coronavirus. It still doesn't make sense to me that people who are tested would have less prevalence of the disease than the general population.
Thank you for the link and the translation Absolute. These early first numbers do have to be interpreted cautiously, remembering also antibody positivity lags by some variable amount but guessed by many to average about 2 weeks. But real numbers!!!

Apidistra antibody levels are evidence of having HAD the infection (or immunization). The swabs are evidence of actively having virus in the nose and/or throat. The two can overlap and in the first weeks more will test positive on the swab for active infection than on the antibody test having shown they are resolved or resolving, but as people resolve more will test positive for antibodies than for being infected.

Make sense?
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Old 04-10-2020, 09:48 AM
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Quote:
Originally Posted by Absolute View Post
The Germany study in Heinsberg has released some early results (the study is not complete).

Translation available here: https://translate.google.com/transla...Xx6t2EHkjp-ap2
.
From there
Quote:
daycare supervisors stay at home for over 60 years.
Supervise a daycare center from home for your entire working and retirement years? Interesting concept.
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Old 04-10-2020, 10:02 AM
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Another complication in measuring the true asymptomatic rate is that you're going to have some people who don't have symptoms from the coronavirus, but who do have them from some completely unrelated source. For instance, I've had a dry cough for my entire life, so me having one now doesn't mean anything. And in a typical winter, plenty of people will have mild respiratory problems just from the low temperatures, the low humidity, or from routine diseases like colds. So yes, when someone say "I don't have any symptoms", they might mean "I have only very mild symptoms", but they can mean "I only have the same very mild symptoms I'd be expected to have without this virus".
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Old 04-10-2020, 10:35 AM
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Originally Posted by DSeid View Post
Apidistra antibody levels are evidence of having HAD the infection (or immunization). The swabs are evidence of actively having virus in the nose and/or throat. The two can overlap and in the first weeks more will test positive on the swab for active infection than on the antibody test having shown they are resolved or resolving, but as people resolve more will test positive for antibodies than for being infected.

Make sense?
Absolute already answered that point - if nobody is trying to translate prevalence in Heinsberg to prevalence in the rest of Germany, then it actually doesn't matter what the prevalence in Heinsberg is.

In that case, the important number is the mortality rate of 0.4%. If you combine that with the German death count of about 2600 then you'ld estimate that the total number of Germans who have/have had it is about 650k rather than than the official 113k

Which, on the one hand, is a ton of missed cases, but on the other hand, not incompatible with estimates I've previously seen of undercounts between about 5x and 20x.

Still less than 1% of the population, sadly. So not very close to the point where we could reasonably expect the proportion of already exposed people to have much of an effect on the infection rate
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Old 04-10-2020, 02:49 PM
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Another complication in measuring the true asymptomatic rate is that you're going to have some people who don't have symptoms from the coronavirus, but who do have them from some completely unrelated source. For instance, I've had a dry cough for my entire life, so me having one now doesn't mean anything. And in a typical winter, plenty of people will have mild respiratory problems just from the low temperatures, the low humidity, or from routine diseases like colds. So yes, when someone say "I don't have any symptoms", they might mean "I have only very mild symptoms", but they can mean "I only have the same very mild symptoms I'd be expected to have without this virus".
From a practical perspective they really can be considered the same: no symptoms that registered as anything of note.
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Old 04-10-2020, 02:57 PM
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Yeah, “asymptomatic” really means no symptoms significant enough to seek medical care or stop normal activities such that there is no reporting or other evidence of epidemic spread and contagious people shedding virus without any preventative measures.

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Old 04-10-2020, 04:19 PM
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Apidistra,

Again, I'd take these very early numbers with great caution, but sure let's play as if we can believe the bit.

IF the true IFR for an entire population rate is 0.4% and herd immunity for the particular population (considering its age demographics and current social structures) for the particular germ occurs at 40% THEN the deaths per million expected before herd immunity kicks in is 1600 deaths per million. Italy, Spain, and New York are all running in the 300s currently.

Why to take the death numbers with such caution? Ganglet's population is just barely over 12K. If they're saying that 14% of them were infected and about 0.4% of those died then the deaths number is 6 or 7. Be very careful extrapolating from small n numbers.

The other way to read it is to simply note that in Germany with a pretty quick control response and lots of testing right away the infection rate seems to have gotten to 15% fairly quickly with 80% of those infected never having realized that they were sick.

I've found a link to the actual preliminary study report. Throwing it into Google Translate is enough to get their methods:
Quote:
A form letter was sent to approximately 600 households. Overall took approx. 1000 inhabitants from approx. 400 households took part in the study. There were questionnaires collected, throat swabs taken and blood for the presence of antibodies (IgG, IgA) tested. The intermediate results and go into this first evaluation Inferences from approx. 500 people. Preliminary result: An existing immunity of approx. 14% (antiSARS-CoV2 IgG positive, specificity of the method>, 99%) was determined. About 2% of the Individuals had a current SARS CoV-2 determined using the PCR method ...
Would love to at least see how well the 500 of the sample reflect the age and household demographics of the town.

500 is a fine first sample but not sure what confidence bounds would be reasonable to place on this. I would not take the 0.4% IFR with much confidence based on this sample, personally.
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