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Lou Jost
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Post by Lou Jost »

RP>> I said nothing about herd immunity. It does not take herd immunity for infections to peak, then fall.
What might make it fall, in your view?
RP>> it is also uncorrelated with timing of shutdowns.
Is that true? Show me a country where the drop happened before mitigation started. You shouldn't expect perfect correlation of the timing, because mitigation usually started slowly and the measures varied greatly between countries.
RP>> All the models I have seen show the shutdowns as causing a delay and reduction in the peak. This was ostensibly their purpose.
I don't understand the connection to what I said.
RP>> I assume this means "yes", yet models say the exact opposite to be expected. That doesn't mean they are right though!
I don't understand this comment either. The drop I have been talking about is the drop in doubling time as shown by the graph I cited at the beginning. There is no contradiction with the models or with the observed curves graphing infections versus time.
Last edited by Lou Jost on Sun May 10, 2020 5:45 pm, edited 1 time in total.

rjlittlefield
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Post by rjlittlefield »

ray_parkhurst wrote:RP>> I said nothing about herd immunity.
Checking the record, your exact words were "The downturns in the data are not due to whether a country went into lockdown, but due to the virus starting to run out of hosts to infect" (emphasis added).

So I am puzzled. How is "run out of hosts" different from "herd immunity"?

--Rik

enricosavazzi
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Post by enricosavazzi »

rjlittlefield wrote:
ray_parkhurst wrote:RP>> I said nothing about herd immunity.
Checking the record, your exact words were "The downturns in the data are not due to whether a country went into lockdown, but due to the virus starting to run out of hosts to infect" (emphasis added).

So I am puzzled. How is "run out of hosts" different from "herd immunity"?

--Rik
The two are obviously very closely related. According to my (quite possibly faulty) understanding, "running out of hosts to infect", if taken literally, means that once 100% of the population has been infected and the survivors have developed immunity, there are 0% hosts left to infect.

Herd immunity, on the other hand, means in my understanding that enough of the population (albeit significantly less than 100%) has developed immunity, and the ones still potentially vulnerable are less likely than before to come into proximity with an actively contagious subject, and therefore statistically (but not 100%) protected by the fact that R << 1. I use << here in the sense of "much less".

Edit: So, if I am right, herd immunity means in practice that there is likely to be a long "tail" of infections slowly decreasing at the end of the pandemic, rather than an abrupt end to it. If herd immunity has not yet been reached, relaxing the lockdown and social distancing recommendations will likely result in a second wave of infection, because relaxing these measures brings R above 1 again.
--ES

Lou Jost
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Post by Lou Jost »

Yes Enrico, that's exactly how the terms are used, and what the effects are.

ray_parkhurst
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Post by ray_parkhurst »

Sorry for late reply. We just returned from 3 days of "necessary travel".
rjlittlefield wrote:So I am puzzled. How is "run out of hosts" different from "herd immunity"?
This is slightly out of context, Rik. I said "started to run out of hosts". If you actually run out of hosts, ie as enricosavazzi says 100% of population is infected, obviously the infection rate should fall to zero and herd immunity is achieved. What I was referring to was the "start" of this process as indicated by the reduction in number of infections, ie the "downturn".

The interesting thing I see in the data (as flawed as it is) is that there is no apparent correlation of the rates of infection increase to the shutdowns, and this was the intent of my original statement to Lou. After the shutdowns were put in place in the US, the rates continued to increase exponentially for many weeks.

Now, it is true that the shutdowns were put in place quite early after the first deaths were recorded, so it is difficult to discern a change in associated rate, but for sure the shutdowns did not correlate in time, even with significant delay, to the downturns.
Lou Jost wrote:
RP>> I said nothing about herd immunity. It does not take herd immunity for infections to peak, then fall.
What might make it fall, in your view?
Based on observations in my area, I have seen a significant increase over time in the observance of "social distancing" protocols. This includes masks and physical spacing. Physical spacing and elimination of physical contact happened early, but masks have only become prevalent in the last few weeks. Most supermarkets have instituted "no mask, no entry" policies in the same timeframe. Stores such as supermarkets and hardware stores also have recently (last few weeks) installed shields between customers and clerks. I can only assume that the improvements are a "human" thing due unfortunately to fear, and that other states and countries have seen the same effect, so my expectation is that the sharp downturns are due to improved social distancing protocols.

Lou Jost
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Post by Lou Jost »

my expectation is that the sharp downturns are due to improved social distancing protocols
Of course, Ray, I agree with that. That's what mitigation does.

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:
my expectation is that the sharp downturns are due to improved social distancing protocols
Of course, Ray, I agree with that. That's what mitigation does.
As a final note, just to be clear...

Social Distancing is not equal to Lockdown/Shutdown

I don't think that the Lockdown/Shutdown on its own could even be called mitigation, but that's probably going too far for many folks. I do agree that there are some businesses which simply can't implement social distancing (eg hair dressers), and closing them is for sure mitigation. Some of these are being allowed to open in parts of the US, with I guess strict mask protocol. Hope that works. I would bet that most businesses could still function with social distancing rules, mandatory masks, etc which as I said above (and you seem to agree, Lou) is the primary reason for the reduced transmission and sharp downturn in cases. It's a shame that these rules were not implemented first,with businesses allowed to stay open rather than shutting them down while still not implementing strong social distancing rules. We might have had both fewer cases and be able to maintain a strong economy, but leadership from the WHO/CDC/NIH/NAIAD/etc was woefully lacking. It's almost as if this was their "first rodeo" the response was so lackluster, slow, and contrary, and convolved with the political response, we got these ineffective and damaging lockdowns.

Lou Jost
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Post by Lou Jost »

I sort of agree with much of what you say, Ray. Surely more nuanced mitigation would have been better. But I do not believe a more nuanced yet effective mitigation would have looked much different from what we have.
Social Distancing is not equal to Lockdown/Shutdown
Granted, it is not equivalent, but lockdown/shutdown does increase social distancing in important and effective ways.

A couple of things are still needed in order to safely go back to work. First, easily available testing. Here the CDC and the Trump administration are to blame, and Trump's repeated denials of problems in this area are practically criminal.

The other thing that is needed is readily available obligatory high-quality N95 (or equivalent) masks. This is another area where Trump's "leadership" is lacking. If we had those, and gloves, I'd feel safe going to work in most reasonably well ventilated spaces during the summer (in many parts of the US it will be impossible to maintain adequate ventilation in the winter). There would need to be a spacious outdoor lunch area though, since masks have to come off then.

Without these things, and particularly without good ventilation, workplaces would become super-spreading centers.

Since we don't have those things in most places, a complete lockdown makes sense while we work on getting the nuances right.

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:
Granted, it is not equivalent, but lockdown/shutdown does increase social distancing in important and effective ways.
It also decreases social distancing in important ways, such as pushing multi-generational households into isolation together, increasing social tensions and domestic violence, etc.
A couple of things are still needed in order to safely go back to work. First, easily available testing. Here the CDC and the Trump administration are to blame, and Trump's repeated denials of problems in this area are practically criminal.
No, testing is not needed. It is too late for testing or contact tracing. What would you do with that information? Are you proposing a "covid passport" or some such nonsense? A much, much bigger percentage of the population has been infected, and had no symptoms, than the symptomatic case numbers indicate. Testing is just an excuse to slow the removal of shutdowns. In reality, testing was useless as soon as the rate turned exponential.
The other thing that is needed is readily available obligatory high-quality N95 (or equivalent) masks. This is another area where Trump's "leadership" is lacking. If we had those, and gloves, I'd feel safe going to work in most reasonably well ventilated spaces during the summer (in many parts of the US it will be impossible to maintain adequate ventilation in the winter). There would need to be a spacious outdoor lunch area though, since masks have to come off then.
Yes, masks are key IMO, but you have to ask yourself "what are these masks for?" Even N95 masks do little to keep you from breathing in virus, so they are not for you, they are to keep you from widely spreading the virus if you are infectious. The problem with many of the N95 masks is they have vents. 3M markets these as "cool flow" or similar. The vents close when breathing in so that the air is filtered, but open on breathing out. Similar valves are included in high-end designer masks, and indeed I have some cool flows as well as some designer types and love them since they keep my glasses from fogging, but my breath goes right out into the atmosphere nearly unimpeded, so they don't really meet the intended purpose. Regular surgical masks are designed to slow the spread of breath, coughs, etc, and are probably much more effective. That said, a big percentage of folks don't put them over their nose, so proper training and regulation of use would be needed. Bottom line, a cheap handkerchief is probably a good enough solution.

Some things you didn't mention was the monitoring of temperatures and coughs. IMO this is more important than any of the above. Folks who are coughing or have fevers should not be allowed to return to work until they are no longer coughing. I suppose this is one area where testing might be useful, to let someone identified as being sick back to work after they test negative.

Edited to add: it's not just going to work, but IMO folks with fevers or coughs should not be allowed into stores, restaurants, etc. In the US it would not be possible to quarantine them, but if every place they go denies entry, they will get the hint that they should just stay home.

Lou Jost
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Post by Lou Jost »

It also decreases social distancing in important ways, such as pushing multi-generational households into isolation together
Not significantly. Multi-generational household members still spent much time together even when working.
No, testing is not needed. It is too late for testing or contact tracing. What would you do with that information?
No, it is essential, and I see you partially agree. If I tested positive for antibodies I would be able to work with more confidence, though we don't know how long or to what degree the immunity lasts. We are rapidly learning those things, though. And if I tested positove for the disease, I would isolate myself if possible. This is a key part of mitigation. I would have thought you would be in favor of testing. It would speed up reactivation. And in small communities it is NOT too late to do contact tracing.

As you must know, half of the cases are asymptomatic [edited spelling, thanks Rik] but highly infective. Temperature testing is a good idea but is not a substitute for real testing. I cannot understand why you would think real testing is useless but testing for symptoms would be great. That makes no sense, given what we know about the disease.

I would note that even the delusional White House now tests the core workers every day. Watch what they do, not what they say.
Even N95 masks do little to keep you from breathing in virus, so they are not for you,
I am asking for good masks that offer significant protection FOR THE WEARER. I think N95 masks are the best widely available masks for that purpose, since that is what health workers use. I would be much happier with a HEPA filter mask. But good masks are key. Vented masks are fine. In poorly ventilated workplaces (like almost all office environments), a mask that only reduces the spreading distance of aerosols is not enough. (However, such a simple mask would be very useful and probably sufficient in environments with good ventilation.)
Last edited by Lou Jost on Tue May 12, 2020 12:51 pm, edited 1 time in total.

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:
No, it is essential, and I see you partially agree. If I tested positive for antibodies I would be able to work with more confidence, though we don't know how long or to what degree the immunity lasts. We are rapidly learning those things, though. And if I tested positove for the disease, I would isolate myself if possible. This is a key part of mitiogation. I would have thought you would be in favor of testing. It would speed up reactivation. And in small communities it is NOT too late to do contact tracing.

As you must know, half of the cases are symptomatic but highly infective. Temperature testing is a good idea but is not a substitute for real testing.
Yes, but that is what the masks are for.

I agree with you about antibody testing giving me confidence. I'd love to know if I have them, so I am greatly in favor of them being available. What I am not in favor of is either active virus or antibody information being tracked or used to gate any of my movements. As long as the testing is anonymous, I'm all for it, but that's not likely going to be the case. But even antibody testing is problematic. There are many strains of the virus extant, and AFAIK the tests are only valid for one strain.

Contact tracing is also a gigantic can of worms, both logistically and legally. What are you going to do with the information? It doesn't take long until a large part of a population is quarantined. This is why I say it is too late, probably even for small communities.
I am asking for good masks that offer significant protection FOR THE WEARER. I think N95 masks are the best widely available masks for that purpose, since that is what health workers use. I would be much happier with a HEPA filter mask. But good masks are key. Vented masks are fine. In poorly ventilated workplaces, a mask that only reduces the spreading distance of aerosols is not useful. (It is very useful in environments with decent ventilation.)
For N95's to be effective for the wearer, they must be replaced after each installation. There are bulk disinfection devices but only hospitals and such can afford to do this. This means the US would require a couple hundred million masks per day, assuming folks would never remove them, even to eat. If we need to include eating lunch, it would double that. Maybe a community disinfection / recycling program could work? I for one would be reluctant to put on a used mask even if it had been disinfected. Masks are fairly personal items.

elf
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Post by elf »

If the virus can only survive for 3 hours on cardboard and 72 hours on plastic, why would you not reuse a mask after 72 hours?

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Post by ray_parkhurst »

elf wrote:If the virus can only survive for 3 hours on cardboard and 72 hours on plastic, why would you not reuse a mask after 72 hours?
According to healthline.com, SARS-CoV-2 can last up to 7 days on plastic. I'm not sure what this means for masks though, since there are many types and the exposed materials vary.

Edited to add: healthline was quoting a Lancet study.

Further edit: all that said, your point is a good one, and perhaps you could get away with owning 14 masks, and rotating them after a week resting period. I personally douse my masks with disinfectant after I remove them, and then re-use them. I don't know how effective it is, but it makes me feel more comfortable about re-using them. The N95 masks are not all that effective at protecting the user anyway, so it is mostly about feeling good about what you're doing.

ray_parkhurst
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Post by ray_parkhurst »

Since we're talking about mitigation, there is a whole additional layer that has received little press: susceptibility. I'm very curious what the folks on this group, who I very much laud as thinking and knowledgable across multiple disciplines, know about the susceptibility question. Certainly the data shows a strong correlation to age, but why? There is also press coverage in both mainstream and alternative media regarding supplements, such as Vitamin D and Zinc. I have my own personal experience but am interested in the experience of others as well.

Lou Jost
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Post by Lou Jost »

Different flus and viruses seem to each have distinctive demographic fingerprints. The reasons for this are poorly understood, but one interesting hypothesis ha sto do with historical accidents; see this for example:

https://www.smithsonianmag.com/history/ ... 180967178/

The most intriguing data on covid-19 susceptibility is the low rate in India. If it lasts, that will need some causal explanation. There is some suspicion that widespread TB vaccines may have helped establish some level of resistance in the population. That would be interesting.

I should also mention an interesting potential treatment. Llamas make a class of very small antibodies that can attach viruses like this one. It appears to be feasible to get llamas to produce these antibodies against the virus and then inject them into people.

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