Zag for Life
NPR recently referenced a New Yorker article which found only 2 cases of child-to-parent transmission of COVID-19 in Iceland, where “extensive contact tracing” was done.
The web article is titled What Parents Can Learn From Child Care Centers That Stayed Open During Lockdowns.
Zag for Life
The number needed to achieve herd immunity depends on the reproduction number (R-value (R-naught, R-[underscore 0])
The formula is susceptible persons < 1/Ro (ie immune persons >( 1- 1/Ro ))
If the R value is 3, we need >67% of persons that are not susceptible (is are immune)
to infection to protect the rest.
If the R value is 2, we need 50%
If the R value is 1, the disease sticks around but doesn’t grow.
If R value is less than 1, we don’t need to worry about herd immunity because 1 person will infect less than one person on average and it will fizzle out on it’s own.
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The R value can be lowered by measures to slow the spread, such as avoiding other persons or wearing a mask. COVID-19-projections.com/infections-tracker has a graph of the initial R -values versus the R-values after mitigation measures. R values are different for different populations, as seen with children, who don’t transmit the disease easily. The R value currently in many places is under 1 or very close to one. It was reassuring to me to learn that R values can change because I have seen so many different estimates for the R-value.
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Any expert who throws out one number for herd immunity is oversimplifying the calculus, is not being forthcoming about assumptions, or has an agenda and is trying to mislead people.
Zag for Life
Thanks for the info JP. I should note that the physician and scientist I listened to were specifically estimating a herd immunity % for Covid based on their best estimate of the R value without precautions. Your additional info is helpful in adding context to this. The point seems to be more clearly that herd immunity without a vaccine or significant social precautions is quite unlikely with COVID-19.Originally Posted by JPtheBeasta
Zag for Life
My disclaimer is that I am learning a lot of this on the fly with the rest of the armchair epidemiologists out there and reserve the right to be wrong on the math or missing nuances of the calculations. I thought the above would be interesting to share, at least.
Banned
FWIW I’ve read and understand the same as you regarding the strong direct relationship between Rvalue and herd immunity critical levels.
Zag for Life
It was a good post. The only clarification I would make is that R0 (nought) doesn't change over time. It's the reproductive number when all people are susceptible, i.e., at the start of an outbreak. The (simplified) formula to calculate how many in the population (%) need to acquire immunity to achieve herd immunity (either by infection or immunization) is 1-1/R0 .. Edit: I just noticed you mentioned the formula. Missed it the first time around.
The effective reproductive number (Re, also written as Rt) is realtime and is what changes over time (due to the things you mentioned).
A very good site to see the state by state breakdowns of Rt is https://rt.live. Just like real time RPI, but for pandemics!
Never in my wildest thoughts did I ever think these esoteric epidemiological terms would become commonplace discussion topics. Yet here we are.
Last edited by caduceus; 06-26-2020 at 01:24 AM.
Zag for Life
https://www.theatlantic.com/health/a...ahMIBejdBBXz5o
THis is worth reading but partially explains the dissonance in data presented by different sources. CDC is often criticized as to their accuracy by me for the past several months. SOme of this explains why. Also though the CDC has become politically infested mor so since the last administration. Everything with a grain of salt......
Zag for Life
This article describes the complications for Kansas State football's team getting workouts and practices started.
https://www.nytimes.com/2020/06/25/s...rus-cases.html
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"thnk god for few" jazzdelmar(12/12/11 12:50pm)
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"When most of us couldn't buy a basket. Where do we get off anyway?!" siliconzag (11/17/06 5:45:41 pm)
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I am monitoring the price of a donut
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Zag for Life
Cad, I have gotten more solid distilled info from your posts than any other one-spot shop. Thanks, I know they take a ton of time.
In the Sun-belt, we're getting hammered. My state hit a new record yesterday and it was near double the previous record, hospital space is almost gone and our state director of public health said we could look like NYC if things don't turn very quickly. Houston is likely worse.
The newest on vaccine development is highly promising, lots of reasons for optimism. But anyone who thinks a vaccine is going to have an impact prior to the end of the year is just dreaming things away, which is how we got to this point in the first place and why the world has literally passed us by. Link:
I think that if everyone does the right thing and we all work together, we may start "getting out of this" late next spring and summer, hopefully with less than 250,000 dead. That appears to me to be "the best case scenario," given that we've blown the best chance we had.The Duke team emphasized that any expectation for a vaccine by the end of this year is overly optimistic.
"I think it's entirely possible that a vaccine will be approved this year, but not at scale," Ridley explained. "We might have some people vaccinated this year, but the average person won't be vaccinated."
Denny added, "We may have some good science by the end of the year and think we have some leading candidates. But manufacturing them to have it all administered, that's a tall order to be ready by the beginning of 2021."
Thanks, Cad.
Whenever you find yourself on the side of the majority, it is time to pause and reflect.
Mark Twain.
Bleeds GU Blue
Sylean - clearly you are unhappy about the stay-at-home orders. But, your post ignores the fact that death is not the only bad consequence of this disease. Younger people who have contracted the disease have developed lung and other problems that will plague them for the rest of their life. There is a related syndrome being found in children that causes significant health issues. I understand the economic arguments about the stay-at-home orders, but think about the economic impact of coming out of Covid-19 with a health-impaired population.
Sometimes we have to look at the greater good, not just our self-serving wants, and do something that is unselfish. In my opinion, staying home as much as possible, washing hands thoroughly, and wearing a mask when you are out are those unselfish somethings right now.
Banned
Cad,
Is the R-0 generally given as a specific number or narrow range everywhere in the world for a novel pandemic?
Or is it localized based on population density, mass transit use, weather, habits (masks tolerance) etc?
I know those things would impact the R-e, but isn’t the reproductive number when all people are susceptible (R-0) still largely a function of human behavior or natural environment? Even what month it is? Is R-0 determined via an average of some of these factors?
Zag for Life
Hi Dix (changed username?),
Sorry to hear that you are now in the eye of the storm. I see that Texas is now reversing course and implementing some (far overdue but weak sauce) measures again. Florida seems to be going for the record. I've been watching the incidence curves, and it's looking ugly for several states. It's distressing. Pandemics generally follow a logistic curve (cases go up linearly for a while, but when you reach a certain threshold, watch out because things go exponential and start doubling very quickly). Outside of mandatory masking and going back to lockdown, I don't see much else that can be done at this point. Sigh. Masks are cheap and easy. Lockdown is not.
The vaccine issue has been an interesting one. I've been amazed that there are clinical trials now in phase III (testing for efficacy with large numbers of subjects). Normally that takes years. I agree that having a safe and effective vaccine, and enough doses to make a dent, ready by the end of the year is probably a pipe dream. Oxford has been saying September for theirs. That would be herculean, but obviously welcome if true.
Ironically, I've wondered if our savior might actually come from the place where it all started -- China. They've been known to move mountains within their society (not always with good ethical standards). Coupled with their massive manufacturing capability, it wouldn't surprise me if a fast(ish)-tracked vaccine came out of there. We'll see.
Stay safe.
Zag for Life
It's regional, and yes, depends on conditions on the ground and in society in that locale. I don't know about seasonality although I would assume not, since that adds a time factor to the calculation. As far as I know, initial R0 calculations involve some modeling and pretty complex math. I'm not an expert in that department.
Zag for Life
Need mulitfactor stepwise descriminant analysis to weight the importance of each of multiple factors. That is coming from the math/statistics dept..
Zag for Life
Trusting China doesn't seem to be a very good evolutionary strategy.
They lied from the beginning. Tried to cover it up by disappearing people trying to warn the world, produced testing kits that routinely gave false readings, sent PPE around the world that was substandard, etc.
If they come up with a vaccine, I wouldn't want to be the lab rat they tested it on.
Bleeds GU Blue
Ain't gonna be no 2020-2021 season y'all. Better get used to that idea now.
"You miss 100% of the shots you don't take."
-Zach Norvell Jr.
Banned
I do think some COVID-controlled countries (Australia /NZ , China?) may see some current Zags playing professionally in lieu of sitting in domestic quarantine.
Zag for Life
Cad I also wanted to thank you for all the time and effort you have put into enlightening us about COVID19. As Dixie stated, you spend an enormous amount of time explaining your knowledge...THANKS!!!
Dixie,
I just finished listening to the Governor of South Carolina explain why he can't mandate people to where face masks/coverings and he said it isn't enforceable...
Italy and Spain had the highest death rates...around 18-20% are figures that come to mind; however, their governments came out strongly about staying home, wearing face masks/coverings and social distancing. Both of those countries have somewhat "recovered" from this contagion and are resuming normal activities.
People in this country do not want to work together to over come this common goal of curtailing this virus. We all should know there is no "I" in the word TEAM but there are just so many people here that are worried about their individual rights and not concerned about the rights of All...Our "leaders" spout how they are limiting testing and don't even want to include the wearing of face masks/coverings as a priority. Without solid leadership, how can this country unite to "fight" the virus...This isn't about politics but rather the health of our countrymen...
It is very sad but I am believing hockeyzag might be right in that we won't have a season this coming year.
People are just so selfish...How did Jesus phrase that commandment: "Love your neighbor as yourself!"
Kennel Club Alum
Cad, I would like to thank you as well. Really appreciate the info and thought processes that go into navigating such a difficult situation.
Zag for Life
I ask the question, “Am I the only one on this board that thinks like I do or is it you feel I’m a nut?
I ask because there are never any comments regarding my posts...
Zag for Life
Nor mine. I just guess that I am too radical, even though my idea would work.
It's not funny.
Zag for Life
New cases today:
USA: 47,341
Canada: 172
Unreal.
Zag for Life
Excellent, science-based article (but an easy read) from National Geographic about where we are, and what we need to do:
NatGeo: Here's How to Stop the Virus from Winning
Zag for Life
Dunno about the science based but it does give a nice overview of common sense things we knew from the beginning but have ralexed on. I get the sense from the data I see daily, that because the DX was insecure from the beginning, we may have to start over using the propertesting. Trouble is, the first test were sent to us ( we actually paid for this!!) was from China. THe testing of the test kits shows a very low sensitivity and specificity.
Soldier on we did though with masks, home, distancing.and it seemed make things better. But how did we know things were "better" when the test were suboptimal...? Nobody knows.
There is a long way to go with this disease unless America buckles down and renews its efforts. HARDCORE.
Even then we can't know where we are except we're in the middle of a storm not of our making. Cad do the newer tests have an improved verifiable increases sensitivity and specificity with an increased predicitive value? Some are still swab and some are serologic. Until our tests are much better, best therapies are hard to define. We still don't know what's best or even better.
Given the uncertainties listed in this post, I think it's hard to assign any blame to this administration.this is an infection that was smuggled in and was lied about.
In my own experience, pts who died, oftentimes were assigned a COVID diagnosis but without testing. I've told the story about one of my janitors who lost his father a few weeks about. 75 yr old ukrainian man who had heart failure with some renal failure as well. He died .and when the son asked , he was told COVID got him. But review of the chart has no testing that might confirm the DX. We now know NYC deaths in the nursing homes often did the same thing..
So for me it's remains a head scratcher. We know the pronicples of defense. But the assurity of DX is still less than certain. For all of you, Mick Mick, a longtime poster just dropped a gem on the BZ basketball board. I hope you'll read it.
Zag for Life
First off, I see that this thread had been delegated to the basement area of the forum. A sad outcome, since 1) It's the damn offseason and there's no reason to relegate threads, 2) It's a thread of significant importance, given the current conditions, and 3) posters have been overall very good about avoiding politics or other contentious issues. And I'll add 4) I think it's been a thread that's educational with a lot of attention, and has had a vibrant discussion about Covid-19. I'm disappointed, and I would plead the moderators to consider to keep this thread in the main MBB forum for the benefit of readers. Inappropriate posts can always be deleted individually. There's no need to use a heavy hand!
Abe -- The article might not be "science based" for you and me - not original articles, but the bulk of the paper was input from epidemiologists, immunologists and public health officials. The PCR tests are largely very accurate. The antibody tests...not so much. Underwhelming specificity, meaning a large number of false positives. Swab, good. Serologic, bad. No worries though, because active viral testing is far more important. Incidence is so much more important than evidence of past infection.
Oh, I blame the federal administration almost 100%. If we had a coordinated response, we would not be dealing with this. Come on, abandon your politics and look at the evidence. They blew it on the test kits. FDA put up road blocks to even see if the disease was in our country, and halted and redirected imports of PPE. The CDC choked on the mask issue.
Stop with the politics. Pay attention to the science. You know the science of stents and anticoagulation, and coronary anatomy. It's no difference with this disease, my friend and colleague.
I already read MickMick's post, and responded. I hope you see it too.
Best, =cad=
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