CharonY

In biosafety facilities the workspace usually has a laminar air flow (top down) to minimize circulation of droplets or aerosols. Horizontal flows would in most cases result in broader distribution. I would think that a similar circulation (i.e. top down) could theoretically reduce spread, but are probably difficult to employ at scale.

The most common element is more extensive contact tracing and follow-ups with testing at the beginning of the infection cycle. I.e. getting ahead of the curve.

Technically, it would be the effective reproduction number (or R sometimes referred to as Rt) as R0 refers to the basic reproduction number which is absent of any intervention of disease transmission and where no immunity exists (though in press I see the terms used rather liberally). In case of SARS-CoV-2 it is even a bit more complicated as both numbers would be the same at the beginning of the infection process as there was no immunity and also no intervention. But aside the nitpick, the idea is indeed to surf the number close to one and hope to keep new cases low(ish). In some areas this does not seem feasible with still relatively high (or unknown) transmission rates.

Perhaps it helps to highlight some of the basic ideas behind the models underlying many of the strategies currently in play. A simple, but frequently used one are SEIR models or their variations. These are simple differential equations calculating how the rate at which folks move from Susceptible to Exposed to Infected and finally to Recovery status. You can think it as a simple compartment model in which the population is part of either of these compartments. Values such as effective reproduction number (how many people an infected person infects), length for which a person is infectious, initial number of infectious people and so on then determine the movement of the population through these compartments. From there, one looks at the expected number of infected folks at any given time and often using age-adjusted models (as well as other info, if available) one can estimate how many folks at any given time might need hospitalization. As the capacities can vary significantly, especially in larger countries, usually more local modelling is conducted to understand the health impact of different infection rates. The major factor that measures such as social distancing and shutdowns are affecting are therefore the expected number of folks being infected in a given time frame (essentially by adjusting the effective reproduction number). This is pretty much an established effect by now, with different estimates for different measures (and areas). So basically the major strategies revolve around these measures, as well as increasing health care capacities, if possible. So one might allow the transmission to increase a little, provided that the health care facilities are free, but may want to shut down again, once they go up. Two critical things we need to know, but don't know yet is how efficient immunization is going to be (either via vaccine or via infection) as well as a how long potential immunity will last. There are models for that, which in the simplest case just has a flow back from Recovered populations back to Susceptible after a certain time.

Actually I do think that this call is premature as well. We would need to look retrospectively at total hearlth burden to assess how damaging this strategy was. There is some truth that they are currently doing worse than their neighbours with over 2000 deaths, compared to 205 (Norway) or 427 (Denmark). Another issue is that Sweden has reported fewer tests, which increases uncertainty somewhat. So while the current trajectory does not look great, I think it takes a bit longer to ascertain whether it is total failure or not.

I think the need was never in question (as well as for the other treatments). Due to the ongoing situation, often the designs are less than optimal and/or part of emergency/mercy treatments. I have a hard time imagining how it would work. Most of the viral particles are not just sitting on tissue, but are inside the cells (or after leaving cells would circulate). I would assume radiation that is damaging to them, would also be harmful (probably more so) to live tissue. After exiting they also disseminate via body fluids so point sterilization does not seem to be the right strategy to me.

I think it should be noted that Sweden has a soft measures, with some restrictions, as well as some school closures. Countries which got ahead of the curve initially also had measures in place as well as overall high compliance to avoid more stringent restrictions. Initially that approach just did not work in Europe although there were some warnings, folks did go to mass gatherings and festivities. Presumably (but not certainly) folks might be more apprehensive now. As SJ Sweden is another live experiment among all the others and we do not have the data yet to clearly declare the right strategy. Moreover, it is too premature to assume that there is or there will be herd immunity. We do not yet have sufficient data to ascertain a) whether folks actually become immune (but also no hard data to contradict) or b) the proportion of infected folks become immune and c) if there is immunity, how long it lasts. The honest truth is that we still have huge knowledge gaps that we need to address. For a pragmatic, soft opening with observation, there also need to be certain structural elements in place. At minimum, it is necessary to have sufficient tests around, so that one can identify and trace new infections accurately and timely, one has to ensure that there are enough capacities in case severe cases spike and sufficient personnel needs to be allocated for timely data collection and dissemination.

I am wondering whether protesters are financially affected. In the US quite a number of these protests were orchestrated by certain ideological groups (https://www.nytimes.com/2020/04/21/us/politics/coronavirus-protests-trump.html). That does not mean that economic anxiety is not a factor for some, but there is certainly something else at play here.

Even without vaccine the idea of flattening is to trickle in serious cases into hospitals in a manageable manner. Ripping off the bandaid would result in much higher number of deaths (as on can see during in the earlier stages in Italy, Wuhan and Spain. Of course initial contact tracing and isolation could have resulted in it burning out, but that ship has sailed.

I dunno, the massive mismanagement of the pandemic response would be a massive thing to distract from. Not sure whether we need anything else.

Eh, politically there is no winning with Trump. There is so much stuff out there, there is no strong strategy to counter any of it. In the impeachment process Democrats tried to run a very narrow focus on things, and it did not help. Also being anti-immigration is always a safe call. And yet another example how the administrations cripples their own response in order to support their narrative. Well, turns out that the WSJ editorial board is also calling it out as a distraction and endangering the economy. https://www.wsj.com/articles/trumps-immigration-distraction-11587511218

That why to some extent it appears to be more symbolic than actually having a practical reason. But it appears that they will also pause green card processing, which would affect folks already in the US, waiting for a green card. At the same time it does not appear to affect folks on immigration work visa. And to me it is not clear what happens if status runs out while waiting in the US for a green card (though probably only few are affected). But for the most part it is just one of the things to show that he still cares about such things to his base, I assume (or a general distraction from their leadership issues in addressing the epidemic).

I do not think they care. It is painfully obvious that xenophobia and nationalism was part of the agenda all along (in fact, aside from dismantling protective agencies, it is one of the few obviously consistent policies) to make America great white again.

There is a minimum required, though it is often not well defined (and a bit stochastic, I.e. the more the likelier it is to become infected). But single particles are very unlikely to result in disease.

Yes, because they get released from sewer lines. There is a reason why they are considered non-potable. If one is wondering whether splash infections are likely, the answer is usually no, as sewage usually at least gets diluted and the measured titer is generally low. The risk is higher if you drink it, but typically bacteria are the bigger issue.

No, but the water is drawn from the Seine and other sources which are downstream from sewer lines (directly or indirectly). Wastewater treatment does get rid of a fair bit via flocculation (if they have such a stage) but removal is not always quantitative.

That is to be expected. If a lot of people are shedding, it will end up in the sewer system and can be detected with sensitive methods.

There is a WaPo article outlining how WHO in conjunction with the US officials have developed WHO policy and has provided the US with early information regarding the outbreak, https://www.washingtonpost.com/world/national-security/americans-at-world-health-organization-transmitted-real-time-information-about-coronavirus-to-trump-administration/2020/04/19/951c77fa-818c-11ea-9040-68981f488eed_story.html

That is an important factor but can somewhat be somewhat addressed by using ELISA instead of rapid tests. The former provides quantitative information which provides a bit more information (but not certainty) regarding possible immunity.

It does look like that they may not have found the right reviewers. Often reviews are long and iterative in nature and I don't think they are good for these fast turnaround papers where we have to assume a lower certainty.

I think in this context it would be good time to have a read what wet markets are: https://www.cnn.com/2020/04/14/asia/china-wet-market-coronavirus-intl-hnk/index.html Also a more common source for zoonotic diseases. Pigs are a good reservoir where assortment of human, swine an avian viruses have been observed and which have been implicated with the 1918 flu pandemic (though not quite clear) and obviously the 2009 swine flu pandemic.

That reads to me like a revision of the facts. By January 30th China reported more Covid-19 cases than there were SARS worldwide and over 200 deaths. They were in total lockdown and reports were coming in that their healthcare system was at the breaking point. Daily deaths were steadily increasing with a slowdown only toward the end of February. Who would see that numbers as state there is no chance of it breaking out? In order to ascertain that, folks needed to ramp up testing in their respective countries and do entry checks and follow-ups. Epi-studies suggest that the lockdown has delayed spread, but it was unknown what was happening at the same time in Europe or US as folks (as some acknowledge) delayed contact tracing. Cases especially in New York were more frequently caused by travelers from Europe than China, for example. It was pretty much in plain sight, the only thing that was not known is how much spread was going on outside of China. This is not something that China could have measured in any form. There were early positive cases detected outside China but testing was not ramped up. The high death rates we see were mostly driven by community infections. Also I will note that I did not claim that there were no deaths in December (at that time point folks did not have a means to proper diagnose it anyway) but I have not seen reports either that they were plenty. The linked article only shows an overall revision of the total count but after a brief skim I did not see timelines attached. Perhaps you can point those out (not that it matters). But again, let's say folks were uncertain about the December numbers. What, again, about the numbers in February? What, numbers would you say would have to be reported to trigger responses? Double the numbers of SARS? That would be Feb 2. Triple? Feb 5. I do understand the need to balance risk for health and economy to some degree. But at the same time, I (and plenty of my colleagues) expected contingency plans that would be triggered once it became clear that things would not hold. This would include a task force that would centrally collect and advise on data, stashing and distributing test kits, check availability of critical health systems (such as ventilators and PPE). At the same time less invasive measures would be implemented (again with central reporting). As well as perhaps limiting big events. Now after the fact we heard that contact tracing was only partially done in e.g. Germany, where they gave up after a few searches, where folks still had large carnival and sports events (and again only partial tracing after they realized infected folks were there). What I find worrying that leaving Trump aside, there were folks like folks in the German RKI who have downplayed risks, not because, but despite the data coming out of China.Other German virologists have been far more worried and starting demanding to have actual plans in place. Which did not come until March. So to be fair, it is not only the US that is failing (though it is doing it spectacularly) but as you said, others have been dragging their feet. One difference that I have observed however, is that in Germany instead of blaming, say, China, they are looking at why their predictions were so off and pinpointed lack of contact tracing as one of the biggest issues (together with initial low testing rates). While I may be dismayed regarding their slow response, at least there is hope for improvement.

So what clear information do you think was missing? After the initial reports Vietnam, Taiwan, South Korea Singapore used that information and started countermeasures. Again, the US and Europe did not start moving until March, so why do you think that knowing something in November would have made a difference if they did not react to the full-blown epidemic in January/February? IF they had reacted immediately after China released data, than they could have claimed that knowing things earlier would have made a difference. But the over one month gap invalidates that. Right now some folks pretend that the information coming of of China since January did not exist which is silly. Even if there was uncertainty in the correct response (which will always exist, in outbreaks you are always over or underprepared) yet things only started moving once it was undeniably there (i.e. in Italy). And again, meanwhile other countries were moving but folks did not learn fast enough from them. I see plenty of criticism mostly by the US but also France and other countries so I do not think that they are quite happy with them. At the same time I want to know what, precisely that impacts or medical preparedness, science and strategy. Because what I am seeing (and what you are also stating) is that because of China fudging something, the rest of the world just could not react. I have several times outlined not only that they could, and should, but also that some actually did. So again, what precisely do you think was hidden that stopped a proper response. It is not the November/December data as folks who reacted using the January data successfully avoided a full lockdown, whereas others who still did not respond (or at least provided emergency plans) had worse outcomes. It was a decision at that point not to anything with all the measures that were going on and getting caught by surprise in March is just myopic, to put it nicely. The reason is that if there was crucial data missing to mount a proper response, we need to know what it is and how to collect it. If on the other hand it is only used as an excuse for lack of planning, then it would imply that we will be caught off-guard next time around again.

No doubt. Folks in the midst of it will only have limited capacity to correctly categorize each death, though I believe that Italy has one of the higher post-mortem tests. In Wuhan for quite some time they counted suspected cases as confirmed ones after using MRI, as they were running low on test capacities and/or wanted to have faster reporting. Everyone involved knows that data is imperfect and will remain for quite some time in most countries.

A few things, the coverage varies a lot between different countries also the case when folks are being tested. Considering that a lot of outbreaks are actually localized rather than nation-wide (depending on size of the country). One thing to look at that sometimes is helpful is how many tests come back negative. Italy also does some post-mortem testing, which other countries don't for example. So roughly 15% of all tests currently administered still come back positive. Contrast that with South Korea where less than 2% of all cases come back positive. The "real" fatality rate is probably lower than the 2-3% reported for the simple reason that many asymptomatic folks will remain unknown. What we start doing now is testing for antibodies that will detect "invisible" infections. Some preliminary local data has been provided for Germany for example (in Gangelt, one of the hotspots of infections) and the death rate there when accounting for undetected cases was closer to 0.4%. In other words the observed crude death rate is also a factor of tests being administered as well as the other factors Stranger mentioned. And of course there is also a matter of definition, as some calculate it based on symptomatic cases exclusively, i.e. case fatality. This basically would only count the likelihood of dying after developing symptoms (a couple of countries including China have waffled a bit in terms of what to report as a case). Again, it would be silly to assume that the world would have reacted differently if China had reported a few percentage points higher or lower. With regard to testing, the reporting was a bit all over the place. Typically two or more tests are administered and initially Italy for example listed counted each test but I think they switched to individuals at some point. That caused a bit confusion to calculate test coverage and makes some data not comparable. Other Countries (such as Germany or US) either did not publish a totals list or referred to individual states (which may or may not have reported). With regard to reporting, I know I got test numbers from Wuhan (via the provincial reporting)a while back but I do not know enough Chinese to effectively dig out data. There was a report in the province in Guangdong which showed about 320,000 tests at the end of February (or 2820 tests per million people). It does look that only from 66 countries we can get convenient national data (although again, they may be different in terms of what is being reported). The correction of death rates on the other hand does look more like an attempt at transparency rather than obfuscation. Most countries will under report deaths unless they do post-mortem testing in all suspicious cases. And countries with limited capabilities will obviously under report more. To be clear, China is definitely not a source that can be trusted with the same level as many other countries. While there is no evidence of systematic data manipulation they could, in theory reduce overall positive as well as death numbers, thus keeping the ratios constant (again, no evidence that they did). But, and this is the important bit, even if they did, and even if they are in a worse shape than they seem to be, it is no freaking excuse for the other countries to not at least create emergency plans and scenarios the moment China started reporting on the outbreak. Cases outside of China (including US) were already been reported leading up to February but without evidence of community spread. So why wasn't there more contact tracing or any kind of travel screening (as shown in other countries shutting down borders is not even necessary). I am repeating myself here, but it is not about whether China is a reliable partner or not. It is about why folks did not act even with the available information (regardless whether they were 100% accurate or not, as you will never get perfect data in a novel outbreak). Infectious disease experts have been making some noise early on and the CDC has made all the right statements come February. And then there is the gaping lack of action until Italy was hit and Europe was starting to get nervous. I suspect much of it is because often Europe looks toward the US in these situation as especially Germany is often unwilling to take lead. Germany produces a lot of the components for the tests and has decent capacity of PPE production and I think I got a notification sometime around March where only then they were asked to increase their production. I.e. folks did not think that they needed the surplus (which is why the first weeks in Germany there was an abysmal rate of tests until they managed to ramp it up). There was a whole lot that could be done and it is perhaps no surprise that countries with with SARS experience responded better. What the rest of the world needs to understand is that infectious diseases will be with us and regardless where you live, there is always a chance for deadly outbreaks. The tendency to think that if something happens elsewhere will never impact us or that where we live is clean and disease-free is an illusion. I am expecting that this situation is a teachable moment for countries that ignored the pandemics and epidemics that have been less consequential for them, but am dismayed that some countries (including China and the US) are instead playing the blame game, as if diseases would care about any of that. There is some evidence that higher viral loads correlate with worse outcomes. Studies are limited, but I can dig them out if you want.