totm april 2020 Coronavirus

[mikegarrison]

4 minutes ago, StrandedonEarth said:

I have to wonder about the population density....

That was my first thought too.

[tater]

1 hour ago, StrandedonEarth said:

I know next to nothing about Sweden, aside from the fact that they produced many great hockey players. But to compare them to the US, I have to wonder about the population density....

A little research tells me that Stockholm has a pop. density of about 13k/sqmi.  The US of A has ten metropolitan regions with at least 13k/sqmi (up to 56k/sqmi for NYC), including roughly 14 million people, compared to 10 million Swedes (almost 9 million urban-dwellers). Given that a virus would spread faster in a denser population, Sweden has a significant advantage there.

Overall, the US is ~36/km², vs 25/km² for Sweden, but we can break it out how you like. Look at the link with the charts you can adjust (deaths, cases, daily cases, daily deaths, whatever). If Sweden was a US State, it would be landing day for day in the middle of the pack of States in terms of outcomes. Interestingly MN is about spot on for pop density, though it only has 1/2 the pop.

We will not know of course until this is all over, but Sweden does not yet look much worse than comparable States/countries that are enacting pretty stiff limitations on activity. The "flatten the curve" rationale is fine, but only if it's actually making the outcome substantially better than not flattening the curve at the same effort level (killing the economy has real costs, and not just as an abstract "the economy," lives are being destroyed or seriously set back). Heck, the pop of Lombardy or Wuhan are pretty much the same as Sweden (10M and 11M, they bracket it). Sweden should have a worse outcome than both of those as they are doing nothing.

US interventions:

Shutting down schools.

Stay at home requests. (various levels)

Shutting down "nonessential" businesses.

Limits on occupancy in essential businesses (stores at a max of 20% of fire marshal occupancy here in NM).

Increased hygiene. (humans actually washing their hands after using the bathroom, etc)

Generic "social distancing" (keeping ~2m from other humans when stuck in groups).

Actually staying home if sick.

 

Which of the above is doing most of the mitigation (assuming mitigation is actually happening)? My guess it's mostly hygiene and staying home if sick for the personal changes, and maybe the school closures for the gov intervention (never got sick like we started getting sick when the kids hit preschool, lol).

My fear is that the government response is a cytokine storm, and we should have closed schools, washed our hands, stayed home sick, and maybe suggested that the elderly stay home and let their families deliver them stuff, or utilize the normal delivery services available.

Unless Sweden does FAR worse than we do, so that relative density, whatever, is noise compared to the body count, then doing nothing was a reasonable option, and doing something less draconian (like washing hands, voluntary distancing, work from home if possible, and maybe closing schools) was a great option.

I'm not saying the current strategy is wrong, but it's not clear that it's right, either.

Edited April 8, 2020 by tater

[Superfluous J]

47 minutes ago, tater said:

I'm not saying the current strategy is wrong, but it's not clear that it's right, either.

If only foresight were as good as hindsight.

In addition to population density there could be cultural differences. Maybe Swedes tend to wash their hands more, generally? Maybe they don't shake hands or hug as much. I don't know I've never been there.

But saying "they're fine we would be too" is a bit too broad a statement for me. Reminds me of the "My grandpa smoked for 95 years and died in a motorcycle accident" as proof that smoking is okay.

[tater]

42 minutes ago, Superfluous J said:

If only foresight were as good as hindsight.

In addition to population density there could be cultural differences. Maybe Swedes tend to wash their hands more, generally? Maybe they don't shake hands or hug as much. I don't know I've never been there.

Maybe they know there is a pandemic, and they voluntarily wash their hands more now? My point is that any mitigation they are doing is voluntary. Stuff that people here would do without being ordered to as well. (though you are right, more Swedes might do it voluntarily than Americans)

 

Quote

But saying "they're fine we would be too" is a bit too broad a statement for me. Reminds me of the "My grandpa smoked for 95 years and died in a motorcycle accident" as proof that smoking is okay.

It's not the same as that at all. Anecdotes are anecdotes. Sample sizes of 10M are another story altogether.

I've never been to Sweden myself, though I've met some of my relatives, and my grandmother was born there. The population of Wisconsin and Minnesota (where my Swedish family is from) is not too dissimilar I'd imagine. Yeah, there are demographic differences in the US, which will play out, but even those could be for corrected for in a comparison (you could weight outcomes by societal age demos, comorbidities, etc). The point is that Sweden is a first world experimental control.

We should not see marked differences in outcomes (weighted to age demos, as age is the primary factor in mortality by far) for places doing more or less the same things to mitigate the spread. If some countries that are similar, European countries have little difference in outcome with NO efforts to mitigate, then the mitigation efforts were not that effective.

Should Sweden end up with ~32X fewer deaths (weighted to any pop age differences) than the US, or half as many as NY State, or whatever number that is similar for some EU analog country that shut everything down, then shutting down didn't stop it, it stopped itself. This is critically important to know. What's R₀? What's R_e with and without different mitigations?

When this dies down, there will be claims that in the US 2 million would have died (nonsense, that was never gonna happen) minus the shutdowns, and there will be others saying "it was just like the flu" or similar, and we should have done nothing at all if the deaths are even close to flu levels (even near 100k in either direction, 1958 flu killed 110k in the US). The way to test these counterfactuals would be a first world controls (Sweden, unless they change what they are doing), and good serological testing to see how many actually had this, and related to that last, what the actual mortality rate is (deaths over total estimated cases).

We only know the CFR because some people show up and get tested, some of those get hospitalized, and some die. For flu 2015-2016, the number tested was ~80,000. That's 0.33% of actual flu cases. If the CFR were calculated like COVID, we'd count ALL flu deaths, even minus a lab test, and divide by 80,000. 23,000 died that flu season, for a CFR of ~29%. Of course they diagnose flu in ways other than testing, so based on hospital admits, CFR would be ~8% (if flu screening was or became std at some point, this would effectively equal the tested pop), and with all medical visits, it would be 0.2%. In short we have no clue what the infection fatality rate actually is. For NY right now, the fatality rate as a function of cumulative hospitalizations is ~17% (about 2X flu using the same CFR methodology, deaths/hospital admits). Given the rough CFR is thought to be ~2% based on testing, if 10X as many people have it as get tested positive, then the real fatality rate will be... 0.2%, 2X flu. I'm not saying that's what it is, but I won't be surprised if that turns out to be the way it is.

Edited April 8, 2020 by tater

[Superfluous J]

40 minutes ago, tater said:

It's not the same as that at all. Anecdotes are anecdotes. Sample sizes of 10M are another story altogether.

So why not use the 60M sample size of Italy instead?

[tater]

7 hours ago, Superfluous J said:

So why not use the 60M sample size of Italy instead?

I was looking for regions that were more equivalent to States in terms of population. You can use Italy, too.

[tater]

Serosurvey happening:

https://www.sciencemag.org/news/2020/04/unprecedented-nationwide-blood-studies-seek-track-us-coronavirus-spread#

[tater]

 

[tater]

More on the "don't be obese" front from France:

https://news.trust.org/item/20200408103237-l2epf

Also, the chief epidemiologist of France is saying that "only" 10-15% of the population has developed antibodies for this, not near herd immunity.

10-15%. (!?)

That would be 33-50 million people in the US. A typical flu season level of infection.

Assume the IHME model is about right, and round up to 90k deaths. That's a IFR of 0.27% to 0.18%.

[tater]

That math was wrong... the IHME model now suggests 60k dead, not 80.

That puts a lower bound on IFR at 0.12% (assuming 15% got sick, 60k dead). Not saying that's the actual value, but the people saying that 0.6% was certainly an upper limit were probably right.

The very early Chinese data had the bulk of China approaching 0.3% after all, so that is probably much closer to the actual value.

Edited April 8, 2020 by tater

[sevenperforce]

9 hours ago, tater said:

When this dies down, there will be claims that in the US 2 million would have died (nonsense, that was never gonna happen) minus the shutdowns, and there will be others saying "it was just like the flu" or similar, and we should have done nothing at all if the deaths are even close to flu levels (even near 100k in either direction, 1958 flu killed 110k in the US). The way to test these counterfactuals would be a first world controls (Sweden, unless they change what they are doing), and good serological testing to see how many actually had this, and related to that last, what the actual mortality rate is (deaths over total estimated cases).

What's the basis for saying 2M deaths w/o mitigation was a nonsense projection?

Serological testing will help but what about respiratory deaths in patients not tested for the virus?

[tater]

9 minutes ago, sevenperforce said:

What's the basis for saying 2M deaths w/o mitigation was a nonsense projection?

Because there was no data to support that at all. The InfectionFR was never 3%, only the CFR, which is a measure of testing, nothing else (for flu the CFR via testing is ridiculously high). It was always true that the actual number of cases was probably 10X tested, up the thread is an early paper I posted that said that the ascertainment rate in China was probably ~5% (multiply confirmed cases by 20, divide CFR by 20). The Chinese data (again, very early) said outside Hubei the CFR was ~0.3-0.4%. if 2/3 of the US got sick, that's 600k dead. You can't even get to a million deaths with 80% of the US infected. To get 2M with 80% infected, you need a infection fatality rate of 0.75%. SK showed that 0.66 was likely an upper limit (and that was STILL based on testing, not estimated actual cases).

Edited April 8, 2020 by tater

[mikegarrison]

@tater You're a good guy, but you seem locked into this "it's no worse than the flu" thing. However, we can all see that it *is* worse than the flu.

Maybe if it were something that most humans had already been exposed to, so the new infections were not all coming in a single pandemic wave, then perhaps it wouldn't be worse than the flu. But that's not the case.

I do feel sorry for the restaurants and barber shops, etc., that were running without a lot of cash reserves and may not survive from this. But the economy will recover. Dead people, not so much.

[sevenperforce]

1 hour ago, tater said:

Because there was no data to support that at all. The InfectionFR was never 3%, only the CFR, which is a measure of testing, nothing else (for flu the CFR via testing is ridiculously high). It was always true that the actual number of cases was probably 10X tested, up the thread is an early paper I posted that said that the ascertainment rate in China was probably ~5% (multiply confirmed cases by 20, divide CFR by 20). The Chinese data (again, very early) said outside Hubei the CFR was ~0.3-0.4%. if 2/3 of the US got sick, that's 600k dead. You can't even get to a million deaths with 80% of the US infected. To get 2M with 80% infected, you need a infection fatality rate of 0.75%. SK showed that 0.66 was likely an upper limit (and that was STILL based on testing, not estimated actual cases).

No data??

The global CFR is 5.79%.

Italy's curve is finally starting to flatten thanks to their extreme (if too late) social distancing measures. The national CFR in Italy, currently, is 12.6%. Assuming conservatively that the 4% of cases currently listed "Serious or Critical" have the same 41% CFR as closed cases in Italy (this assumes hyper-conservatively that no recovered patients were ever listed as "Mild Condition"), that ticks up to a national Italian CFR of 13.8%.

If the US had not taken any mitigation measures, we likely would have been worse-off than Italy. A national CFR of 13.8%, using your numbers ("the actual number of cases was probably 10X tested"), corresponds to a national IFR of 1.4%, which gets you 2M dead with just 44% of the population infected. 

Remember that you need ~50% population infection to get passive herd immunity and bring transmission rate down to flu-like levels.

The only way to argue against these numbers is to say that it is unrealistic to think that the US would have been worse off than Italy without mitigation measures. Even though Italy has already started to flatten the curve, its death rate for closed cases is 41%. The US has a death rate for closed cases of 37.2% and its curve is still concave up.

@tater, you can continue to insist that the US could never have been as bad off as Italy even if we had done nothing at all, but that's a hard sell when we have had mitigation measures for weeks and our CCFR is already within 4 percentage points of Italy's.

[tater]

46 minutes ago, mikegarrison said:

@tater You're a good guy, but you seem locked into this "it's no worse than the flu" thing. However, we can all see that it *is* worse than the flu.

I have never once said that. I have consistently said it is multiples of the flu. 2--5X worse as the likely value. 3X flu is 3 times worse than flu. Flu spikes already put hospitals on divert, so 3X flu is very bad, indeed (which I have said consistently in this thread). It doesn't have to be 30X worse than flu to be bad, what multiple of flu does one have to assume is true to not be labeled as you just suggested I be labeled? If I say "10X flu" I'm good, but if I say 4X flu I'm a redneck denier? The data will tell in the end. Deaths/total cases (not tested, estimated for both numbers, exactly as flu is every single year). If total cases is not at least 10X tested I will be incredibly surprised.

 

45 minutes ago, sevenperforce said:

The global CFR is 5.79%.

CFR is meaningless. It tells us some deaths over cases that happened to be tested. Deaths are not even known, look at deaths at home that will have to be retrospectively added to the COVID-19 toll. It parts of Italy perhaps doubling the number from what was posted up thread. GIGO, and all the numbers are garbage right now, unfortunately.

Total or infection fatality rate is what matters (actual deaths/actual cases). The CFR for flu is NOT 0.1%, for example, the infection fatality rate for flu is 0.1% since the numerator and denominator for flu is estimated every single year. Using the same metrics as COVID CFR, deaths over positive tested cases, the flu has a CFR of almost 30%. We all know that number is BS, because we know only a tiny fraction of flu is tested. Flu deaths over hospitalizations is ~8%. That's a better and more useful number since if you are sick enough to be hospitalized, it tells you about your chances. For COVID-19 in NYS right now, the deaths over cumulative hospitalizations is ~17%. Over active hospitalizations it's ~31%, so the real fatality rate among those hospitalized is likely in between those 2 values. The average of the 2 values is 24%. 3X flu hospitalization fatality rate, interestingly. If it's closer to the 31%, then maybe more like 4X flu. 4X flu is really bad, that could be 240k dead matching flu like %s of people infected.

Edited April 8, 2020 by tater

[DDE]

Asymptomatic =/= no damage

Chest CT Findings in Cases from the Cruise Ship “Diamond Princess” with Coronavirus Disease 2019 (COVID-19)

Still wanna bet on herd immunity?

[tater]

1 hour ago, sevenperforce said:

@tater, you can continue to insist that the US could never have been as bad off as Italy even if we had done nothing at all, but that's a hard sell when we have had mitigation measures for weeks and our CCFR is already within 4 percentage points of Italy's.

Forgot this. One, the CFR doesn't matter as I said, we need an actual number, or a good estimate, and CFR is not a good estimate for the reasons I stated. Testing gives ~30% false negatives, and testing only tells you who has the min viral load NOW, so some tested have it, but test negative, some have it, but are tested before they are shedding enough virus to measure, some are tested after they had it, and are not shedding virus. Only a combo of antibody testing with viral load testing will get us really good data. The sooner the better, obviously.

Testing remains focused on the symptomatic. NYS testing is running ~40-50% positive, but they have only tested about 1.8% of the population (assuming that total tests never tested the same person more than once, which seems unlikely). So we know that 1.8% of NYS felt sick enough in the COVID-19 era to go get tested, and about 41% were positive. That's going to increase, clearly, but new positives is at least flattening. We also know that the docs are treating people with the symptoms as positive, regardless of testing. Wonder how those get reported, though...

The idea that I am unconcerned is wrong-headed, I want an accurate picture, I'm more likely to get this than most people on this forum, my wife comes home from doing things to people in the ER several days a month, and from seeing a random selection of sick people (untested), and doing invasive things to them, every single day of the week. I'm just trying to be realistic about it and the impact it will actually have (I feel sorry for all the cancer patients having to live with their cancer growing for X more weeks until they are sick enough the hospital no longer thinks their surgery is "elective," too).

 

32 minutes ago, DDE said:

Asymptomatic =/= no damage

Chest CT Findings in Cases from the Cruise Ship “Diamond Princess” with Coronavirus Disease 2019 (COVID-19)

Still wanna bet on herd immunity?

Interesting. Wonder how long the damage takes to repair (assuming it does).

More on this:

https://www.sciencemag.org/news/2020/04/survivors-severe-covid-19-beating-virus-just-beginning

Edited April 8, 2020 by tater

[StrandedonEarth]

15 hours ago, tater said:

(never got sick like we started getting sick when the kids hit preschool, lol).

Yeah, my wife has worked in several daycares and refers to them as “petri dishes”, which would make a good name for one lol. We went through the same thing, but once we’d finally blown the continuous colds out of our systems, we were immune to every bug in town

Also, I heard on the radio that since  Durex, which makes 20% of the world’s condoms, had to shut down, there may be a condom shortage looming. That’s another whammy that’ll add to the Coronial boom

Edited April 8, 2020 by StrandedonEarth

[magnemoe]

10 minutes ago, StrandedonEarth said:

Yeah, my wife has worked in several daycares and refers to them as “petri dishes”, which would make a good name for one lol. We went through the same thing, but once we’d finally blown the continuous colds out of our systems, we were immune to every bug in town

Also, I heard on the radio that since  Durex, which makes 20% of the world’s condoms, had to shut down, there may be a condom shortage looming. That’s another whammy that’ll add to the Coronial boom

Her in Norway they are starting up the daycares again, same with schools for young kids sounds a bit dangerous to me as you say they are petri dishes, some other moves like opening technical collages to use workshops to get graduations. They are young adults who take orders better than young kids who can be compared to intelligent cats in their ability to follow orders over time.

Need to get some fixes and service on my car, the garage have problems getting parts as most of the warehouses are in other countries. Depend a bit of part types and car brand, if its common replaced parts they often have it locally, if you have an Italian car you have an problem. 
 

[mikegarrison]

25 minutes ago, magnemoe said:

Need to get some fixes and service on my car, the garage have problems getting parts as most of the warehouses are in other countries. Depend a bit of part types and car brand, if its common replaced parts they often have it locally, if you have an Italian car you have an problem.

Yes, well keeping an Italian car running can be a problem even in the best of times.

[tater]

Estimates of the % of symptomatic cases ascertained by country:

"Using a delay-adjusted case fatality ratio to estimate under-reporting"

https://cmmid.github.io/topics/covid19/severity/global_cfr_estimates.html

Says for the US they estimate 12% of symptomatic cases have been detected (9.8%-27% is the uncertainty range).

The % of asymptomatic cases (presumably this means either no symptoms at all, or so mild people don't think about it, like what most kids apparently get from this) is not really well established, the Chinese said "at least 59%," and I've seen numbers from 10% to 90%, so who knows. Regardless, this lends credence to the idea that the true number of cases is substantially higher than the cases ascertained via testing.

 

Some interesting stuff about R₀ (which seems a mess to me because it's really hard to characterize)

Spoiler

 

https://www.scientificamerican.com/article/the-unforgiving-math-that-stops-epidemics/

(think I posted this ^^^ up thread before)

Also:

https://ajph.aphapublications.org/doi/pdf/10.2105/AJPH.2013.301704r

This is interesting:

https://www.medrxiv.org/content/10.1101/2020.02.10.20021725v1.full.pdf

 

 

 

 

[sevenperforce]

2 hours ago, tater said:

...for the US they estimate 12% of symptomatic cases have been detected (9.8%-27% is the uncertainty range).

The % of asymptomatic cases (presumably this means either no symptoms at all, or so mild people don't think about it, like what most kids apparently get from this) is not really well established, the Chinese said "at least 59%," and I've seen numbers from 10% to 90%, so who knows. Regardless, this lends credence to the idea that the true number of cases is substantially higher than the cases ascertained via testing.

I agree 100% that the true number of cases is substantially higher than the number of cases ascertained via testing. That's not at issue. The question is probability space. Would it have been reasonably possible (absent containment/mitigation measures) for the US to have a CFR similar to Italy and an ascertainment rate high enough to get 2M deaths with under 50% population infection? I don't think we can say with any degree of certainty that the answer is no.

R₀ is a huge variable here. Measles and varicella have an R₀ of 10-18 in a completely susceptible population. The only reason they don't sweep across the country in massive epidemics is that we have 90% or more herd immunity via vaccination. The value you're really looking for is R_e, or effective reproduction number. The operative equation is R_e = R₀X, where X is the percentage of susceptibility in the population. The average flu vaccine is 67% effective and on average 63% of the population is vaccinated, which gives you an X = 0.58. Seasonal flu has an R₀ of up to 2.1, so that's an effective reproduction number of 1.22. Compare to COVID-19's R₀ of up to 3.9 and the gravity of this comes into light.

Let's think about it this way. At what point will the odds of catching COVID-19 be equivalent to the odds of an unvaccinated person catching the flu? The math is simple. If we use the upper bounds for the flu and COVID-19, then you need 68.7% population infection; if we use the lower bounds (R_{e_flu} = 0.522, R_{0_C19} = 1.4), then you need 62.7% population infection. 

In other words, your odds of catching COVID-19 become no greater than your unvaccinated odds of catching the seasonal flu when 63-68% of the U.S. has been infected. That's 215 million infections. If InfectionFR > 0.93%, that's two million deaths. 

[tater]

41 minutes ago, sevenperforce said:

I agree 100% that the true number of cases is substantially higher than the number of cases ascertained via testing. That's not at issue. The question is probability space. Would it have been reasonably possible (absent containment/mitigation measures) for the US to have a CFR similar to Italy and an ascertainment rate high enough to get 2M deaths with under 50% population infection? I don't think we can say with any degree of certainty that the answer is no.

Herd immunity is a function of R₀, and R₀ is just garbage from what I can tell.

Re is maybe what you could actually measure in a closed population, though I think retroactively, and only with really good serologic testing. Trouble is for R₀ you need to accurately know the curve, so you can work out the true rate of growth, you need PCR testing and serologic in tandem (the former to show who is infected at a given moment, the latter to see all the people you missed).

 

Quote

R₀ is a huge variable here. Measles and varicella have an R₀ of 10-18 in a completely susceptible population. The only reason they don't sweep across the country in massive epidemics is that we have 90% or more herd immunity via vaccination. The value you're really looking for is R_e, or effective reproduction number. The operative equation is R_e = R₀X, where X is the percentage of susceptibility in the population. The average flu vaccine is 67% effective and on average 63% of the population is vaccinated, which gives you an X = 0.58. Seasonal flu has an R₀ of up to 2.1, so that's an effective reproduction number of 1.22. Compare to COVID-19's R₀ of up to 3.9 and the gravity of this comes into light.

That Measles R₀ is a huge range, hence "garbage" IMO. It's like saying the Raptor has an I_sp of 175 to 350, now plan a mission with it, lol.

At 10, you need 90% immunity for herd immunity, at 18 you need 94%.

How did they calculate R₀ for COVID? I mean very specifically, what did they measure, and what was an assumption? If 20 different people did the work, do they all get the same number? No, they will get ranges from low 1.x to 9 or something (because I have seen values all over the map for it). It's a litmus test on the researcher's priors. I said way up the thread I thought R₀ was a garbage number, and they should probably just lump them into a couple categories, low, medium, and high transmissibility. Measles at the high end, flu probably in the middle.

PCR testing can't get the the number unless they take a group like the cruise ship, and not just test them, but test them pretty much constantly, without letting them go, for many weeks (not ethical). Even then "contact tracing" helps, but if it lives on surfaces for days... nope, they touched the supply room door knob, then picked their nose and got it. You need not just how many get it, but in fact how (is never leaving a closed environment filled with virus coated surfaces normal?).

 

Quote

Let's think about it this way. At what point will the odds of catching COVID-19 be equivalent to the odds of an unvaccinated person catching the flu? The math is simple. If we use the upper bounds for the flu and COVID-19, then you need 68.7% population infection; if we use the lower bounds (R_{e_flu} = 0.522, R_{0_C19} = 1.4), then you need 62.7% population infection. 

In other words, your odds of catching COVID-19 become no greater than your unvaccinated odds of catching the seasonal flu when 63-68% of the U.S. has been infected. That's 215 million infections. If InfectionFR > 0.93%, that's two million deaths. 

68% of people never get the flu.

R₀ for flu is usually set at ~1.3 (no vaccine). Herd immunity ( 1 - 1/R₀) for flu at 1.3 sets in at 23% of the population. If 23% had COVID-19 over this season until June, then that's ~76M cases. If the IHME model is right, and we have 60k dead, then the IFR is 0.08%. I'm not gonna set the IFR arbitrarily, then multiply by millions and get terrified. I've heard plenty of epidemiologists say it's certainly going to come in well below 1% in retrospect when we can estimate the total cases better. Below 0.6, in fact.

Heck, the IFR is also not a static target, even if we know the total cases. Why? Because it's an average. COVID-19 doesn't kill people randomly. It kills old, fragile people, and or people with obesity, and all kinds of other (often related) comorbidities. We run out really old people to take out, then it's not taking out 0.whatever % of 20 YOs. So take the 68% of people somehow get this (R₀= ~3 for herd immunity at that %), and the ascertainment is ~10% (for easy math), to the IFR for 70+ is maybe 0.8% (tested CFR 8%) We lose 0.8% of that age group. We lose maybe 0.3% of 50-69 YOs. Under that? it's 0.0X and 0.00X% (or lower). The number killed would scale to the size of those age brackets.

I'm not saying R₀ is 1.3 for this, BTW, I have no idea, and I honestly think that anyone claiming a good R for this is pulling numbers out of thin air. I really wish it was something objective. Measure virus, observe R₀. It isn't, in fact, there seems to be little difference I can see between R₀ and R_e, except that the latter modifies what they have decided to use for R₀. Modifies it by just making a guess. "This probably reduces transmission by 10%!" No one knows. Yeah, you can do a particle model, and say some stop moving, etc, but people are not particles, and we don't randomly interact, we see the same people over and over. R₀ seems to also depend on dwell time with the contact, but in no measurable way to provide a truly objective answer.

 

 

Edited April 9, 2020 by tater

[sevenperforce]

4 minutes ago, tater said:

43 minutes ago, sevenperforce said:

 Measles and varicella have an R₀ of 10-18 in a completely susceptible population.

That Measles R₀ is a huge range, hence "garbage" IMO.

Varicella is 10-12, which is a low range; measles is 12-18, which is a higher range but not as huge as 10-18. Here's an article explaining why the measles number is so broad. But the lower bound of 12 is still bad.

6 minutes ago, tater said:

I'm not saying R₀ is 1.3 for this, BTW, I have no idea, and I honestly think that anyone claiming a good R for this is pulling numbers out of thin air. I really wish it was something objective.

R₀ for COVID-19 is estimated between 1.4 and 3.9:

• https://pubmed.ncbi.nlm.nih.gov/31995857
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001239
• https://www.nature.com/articles/s41591-020-0822-7

I would wager money that the biggest reason why R₀ is higher for COVID-19 is the lengthy, contagious, asymptomatic incubation period. It's like HIV: you don't know you have it until after you've given it to three other people.

[tater]

11 minutes ago, sevenperforce said:

Varicella is 10-12, which is a low range; measles is 12-18, which is a higher range but not as huge as 10-18. Here's an article explaining why the measles number is so broad. But the lower bound of 12 is still bad.

Absolutlely, but if there are different numbers, it's not R₀, it's the effective number (IMHO), the former should not vary, and should be the same answer no matter who does the math. If 100 people can get 100 different answer that vary that much, it's not rigorous. If we set a constant, it's, you know, a constant.

 

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R₀ for COVID-19 is estimated between 1.4 and 3.9:

• https://pubmed.ncbi.nlm.nih.gov/31995857
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001239
• https://www.nature.com/articles/s41591-020-0822-7

I would wager money that the biggest reason why R₀ is higher for COVID-19 is the lengthy, contagious, asymptomatic incubation period. It's like HIV: you don't know you have it until after you've given it to three other people.

Early papers had it higher than that. Much higher. A more recent paper says 5.7

https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article#tnF5

Again, the numbers are all over the map. Plug a seed case into an SIR epidemic grapher with a R0 of 6 and see how many cases you have in a few months. I just messed with one with a seed of 1 case in mid Nov, and R0 5.7, and by late January there are 3 million dead in China. Clearly not 5.7—but that shows how goofy the calcs are.

I don't think many people are catching it from asymptomatic people, honestly, except maybe in prolonged, close contact. Apparently family members only get it 10% of the time, they'd catch Measles walking in the room with a case, lol (if they were dumb enough to be unvaccinated, or got a bad batch—my wife had Measles as a kid, her vax was a bad batch, the young doc had no idea what it was, the old guy looked through the open exam room door and said "Measles" and left).

 

 

Edited April 9, 2020 by tater