# Asymptomatic infection rates **URL:** \ **Category:** The Quarantine Zone\ **Tags:** covid-quarantine\ **Created:** [April 5, 2020, 8:17pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145 "2020-04-05T20:17:16Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [April 5, 2020, 8:17pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/1 "2020-04-05T20:17:16Z")
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](https://www.statnews.com/2020/04/04/cdc-launches-studies-to-get-more-precise-count-of-undetected-covid-19-cases/). > [@](#): > > 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](https://www.nytimes.com/2020/04/04/world/europe/germany-coronavirus-death-rate.html?algo=top_conversion&fellback=false&imp_id=882060058&imp_id=76515522&action=click&module=Most%20Popular&pgtype=Homepage) is planning to do similar widespread seroprevalence testing, but not until the end of the month. > [@](#): > > 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.](https://www.sciencemag.org/news/2020/04/these-are-answers-we-need-who-plans-global-study-discover-true-extent-coronavirus) > [@](#): > > 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. > [@](#): > > 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. ---
**Author:** ![Quint](https://avatars.discourse-cdn.com/v4/letter/q/76d3ee/32.png) [@Quint](https://boards.straightdope.com/u/Quint)\ **Post date:** [April 5, 2020, 8:36pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/2 "2020-04-05T20:36:02Z")
[Iceland](https://www.cnn.com/2020/04/01/europe/iceland-testing-coronavirus-intl/index.html) looks to be a good source of information on this also. ---
**Author:** ![RivkahChaya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rivkahchaya/32/8919_2.png) [@RivkahChaya](https://boards.straightdope.com/u/RivkahChaya)\ **Post date:** [April 5, 2020, 8:43pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/3 "2020-04-05T20:43:37Z")
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. ---
**Author:** ![nearwildheaven](https://avatars.discourse-cdn.com/v4/letter/n/90db22/32.png) [@nearwildheaven](https://boards.straightdope.com/u/nearwildheaven)\ **Post date:** [April 5, 2020, 8:55pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/4 "2020-04-05T20:55:21Z")
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. ---
**Author:** ![MarMac83](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@MarMac83](https://boards.straightdope.com/u/MarMac83)\ **Post date:** [April 5, 2020, 9:05pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/5 "2020-04-05T21:05:08Z")
Seroprevelance? Are you just making up words? ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [April 5, 2020, 9:11pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/6 "2020-04-05T21:11:16Z")
> [@MarMac83](#): > > Seroprevelance? Are you just making up words? [Seroprevalence](https://www.merriam-webster.com/dictionary/seroprevalence) > [@](#): > > 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. ---
**Author:** ![MarMac83](https://avatars.discourse-cdn.com/v4/letter/m/a5b964/32.png) [@MarMac83](https://boards.straightdope.com/u/MarMac83)\ **Post date:** [April 5, 2020, 9:17pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/7 "2020-04-05T21:17:28Z")
> [@running\_coach](#): > > [Seroprevalence](https://www.merriam-webster.com/dictionary/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. ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [April 5, 2020, 9:56pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/8 "2020-04-05T21:56:51Z")
> **['Between 25% and 50%' of people who get the coronavirus may show no symptoms,...](https://www.sciencealert.com/here-s-what-we-know-so-far-about-those-who-can-pass-corona-without-symptoms)** > > Experts think that at least one in four people who get the coronavirus are asymptomatic or transmit it before symptoms show up. > [@](#): > > 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. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [April 5, 2020, 10:20pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/9 "2020-04-05T22:20:14Z")
No, seroprevalence is perfectly cromulent. ---
**Author:** ![Tigers2B1](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@Tigers2B1](https://boards.straightdope.com/u/Tigers2B1)\ **Post date:** [April 5, 2020, 10:34pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/10 "2020-04-05T22:34:49Z")
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. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [April 5, 2020, 10:37pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/11 "2020-04-05T22:37:11Z")
> [@Dr\_Paprika](#): > > No, seroprevalence is perfectly cromulent. And the seroprevalence rate of serum porcelain titers is still essentially zero. 😃 ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [April 5, 2020, 10:38pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/12 "2020-04-05T22:38:35Z")
> [@Tigers2B1](#): > > 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. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [April 5, 2020, 10:39pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/13 "2020-04-05T22:39:52Z")
> [@Wesley\_Clark](#): > > [It's Estimated 1 in 4 Coronavirus Carriers Could Be Asymptomatic. Here's What We Know : ScienceAlert](https://www.sciencealert.com/here-s-what-we-know-so-far-about-those-who-can-pass-corona-without-symptoms) 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: > [@](#): > > “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. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [April 5, 2020, 11:19pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/14 "2020-04-05T23:19:30Z")
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. 🙂 ---
**Author:** ![ThelmaLou](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thelmalou/32/390_2.png) [@ThelmaLou](https://boards.straightdope.com/u/ThelmaLou)\ **Post date:** [April 6, 2020, 12:27am UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/15 "2020-04-06T00:27:58Z")
> [@Dr\_Paprika](#): > > 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_. > [@](#): > > 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. 🙂 ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [April 6, 2020, 1:17am UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/16 "2020-04-06T01:17:44Z")
No, that’s not what I meant. “Forget it, Jake. It’s China-town.” ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [April 6, 2020, 2:54am UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/17 "2020-04-06T02:54:43Z")
Was punning on pyretic, but yours works too. ---
**Author:** ![elbows](https://avatars.discourse-cdn.com/v4/letter/e/b3f665/32.png) [@elbows](https://boards.straightdope.com/u/elbows)\ **Post date:** [April 6, 2020, 3:05am UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/18 "2020-04-06T03:05:15Z")
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!) ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [April 6, 2020, 3:43am UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/19 "2020-04-06T03:43:02Z")
> [@elbows](#): > > 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. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [April 6, 2020, 12:12pm UTC](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145/20 "2020-04-06T12:12:46Z")
> [@Dr\_Paprika](#): > > Was punning on pyretic, but yours works too. I got what you meant! China, porcelain, pyrex, it is to laugh! 😉 [Next page](https://boards.straightdope.com/t/asymptomatic-infection-rates/851145.md?page=2)