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Now that there are vaccines on the horizon, we are hopefully entering a the final stage of this battle with the Coronavirus. However, now is not the time to relax. Instead it is time to double down. To be extra careful. The prevalence of infection is higher than its ever been and there is much danger in the coming season.
Simply put, don't be Augustus I Root. Lieutenant Root died August 8, 1865 at Appomattox Courthouse. The next day the little town would witness the surrender of General Lee and the Army of Northern Virginia. This is a personal connection, my wife and Augustus share a common Root ancestor from the early 1700s in Connecticut. The virus is absolutely at its most dangerous. There are more people walking around infected than at any previous time. Rural areas are the hardest hit with extreme limitations on beds, doctors, and especially nurses. We are weary. Politics of all things have entered the equation. Do not let down your guard. This holiday season would be incredibly hard. Hard to stay away from loved ones, but I think harder still to witness the coming loss in life that is largely baked into the recent rise in cases. I see nothing in the data that says daily deaths won't be about 2% of detected cases four weeks out. So as we approach 200,000 cases per day, we can expect 4,000 or more deaths per day by latter December. If we accelerate the rise due to Thanksgiving gatherings, that could easily climb to 5,000 or 6,000 or more. The best way to love your loved ones this year via a zoom screen so that ALL of you can gather next year, with no unnecessary empty seats at your Thanksgiving Feast. For more details on the death of Augustus: https://www.facebook.com/AppomattoxNPS/posts/lieutenant-colonel-augustus-i-root-many-visitors-to-the-park-are-surprised-to-le/1058182690879079/
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In order for society to re-open we need to think about how to be around each other without at least reducing if not eliminating the likelihood of infecting one another. To me that piece is a TECHNOLOGY problem. We need to get creative in how we think about social distancing, rapid screening, mask effectiveness, air flow and other issues. I see mostly talk by the news and politicians about WHEN we reopen and WHAT phases but not all the details that go beyond hope.
A quick word about WHEN: I’m a big advocate of the approach Pennsylvania and other northeast and mid-atlantic states are taking. They have objective standards to begin opening and for each phase of opening. Basically its less than 50 new cases per 100,000 population over 14 days. I believe this is by county. https://www.governor.pa.gov/process-to-reopen-pennsylvania/ Needless to say its going to be awhile around Philadelphia. I have a pretty dim view on how some states are just opening when their trends are still going in the wrong direction (hospitalizations are still rising strongly in Texas for example). OK, we should probably wait a little bit longer in most places before we open. But that’s not my purpose here. My question is—how do go out in public and work spaces without spreading Covid-19? For the purposes of this discussion I’m saying if no shirt, no shoes, no service is acceptable, then why not add no mask, no screening no service as well? Others can have the political debate. Screening We all know that Sars-CoV-2 specific testing is not readily available as a screen. Many places around the world are using temperature. Certain spaces such as public transportation, airports, and workplaces (lets kick sports/entertainment until at least mid-summer please) should at a minimum be screening for fever. Yes, its not perfect but its certainly better than not testing. Aside from temperature, it seems like there should be some way to optically look in the throat for signs of generalized infection (some type of spectroscopy?). Is there a signal in breath that indicates illness? I imagine a gatlin gun style air sampler that each person blows into and an quick analysis is done (seconds), after each person the machine brings a new sterile sampler out for the next person (the bottom of the machine disinfects (UV?) and removes the spent sampler and replaces with a new sterile one. Blood oxygen by pulse-ox meter is non invasive and quick as well and may indicate infection. All of these screens are designed to take only seconds. Persons that pass the screen proceed, those that fail have two options—a specific Covid test and/or use of specialized masks if there purpose is essential. Masks Again, these should be mandatory for the time being in indoor spaces or crowded outdoor spaces. This NHK piece demonstrates how micro-droplets can persist at face level for long periods of time in poorly ventilated rooms. https://www3.nhk.or.jp/nhkworld/en/ondemand/video/9999604/ Lets just assume that everyone should wear masks, the question is what is effective? The general concept is that everyday masks are best at keeping my infection out of the air around me, not so good at keeping infection in the air from getting in me. That is they work collectively much better than individually. However, I often see material so thin I can see teeth, I see noses peaking out above or lower lips peaking out below masks. What materials are best? What designs allows everyone to get a fit? I am currently using a cloth mask made my daughter. It has two layers with a pocket to put into some type of filter media. I am using blue shop towels folded over in “3-ply”. I am thinking about adding some kind of metal strip between the layers that I can use to pinch around me nose (similar to a dust mask). I have exactly zero data on the mask efficiency. Looking online I find things such as the bioscarf ( https://www.bioscarf.com/ ) which look intriguing, but the cost is probably prohibitive for the average person. I could imagine businesses buying something like this in bulk for workers. A common complaint is that people fell claustrophobic when wearing a mask. Perhaps there is a small fan/hepa filter device one could wear that would bring a very slight positive flow/pressure of fresh air in to the breathing space. Perhaps something that could be a fanny pack size and location with rechargeable batteries? Bottom line-we need to be able to figure out personal filtration to both greatly decrease transmission rates and individual risk. Ventilation This study from China shows a real world review of transmission in a restaurant. https://sfist.com/2020/04/22/study-restaurant-covid-19-outbreak-in-china/ The person sitting near the AC unit was shedding virus. 10 people in the airflow pattern (over about an hour) became infected. People outside of the flow pattern did not get infected. To me, this indicates that we need to bring in fresh air or hepa filtered recirculate air. There needs to be high turnover and a net down flow of the “clean” air to push particles toward the floor. Physical barriers between restaurant patrons and co-workers could maintain smaller zones of common airspace. The outbreaks in meat packaging facilities seem to indicate that these spaces are exceptionally vulnerable to transmission. The highly publicized Smithfield Pork plan in South Dakota initially had their employees use an extra hair net as face masks. Laughably bad, clearly OSHA should be playing a major role, but again that is a political discussion I’m leaving to others. It does make me wonder-if the workers can so easily infect each other, whats going on with my food? Sanitation It is unclear how much spread is by physical or smear contact. This is one area where folks seem to be pretty vigilant with hand washing and sanitizer use. Stores are spraying down carts. People are using gloves (but again how effectively). What needs to be done here is some clear studies on what is most effective. Sometimes wipe downs are more perfunctory and maybe not done with good attention to detail. Can high turnover items like shopping carts spends short interval in UV booth? Are there coatings that be put on handles, doorknobs, etc? How frequently should things be wiped down? Social Distancing Most stores in my area have limits on capacity which is a good start. A friend had a great idea—for places like hair salons, why not make our cars the waiting room? They can just text when it’s your turn to come in. Summer is fast arriving, this gives restaurants a lot of opportunity to setup outside spaces to augment spaced out indoor seating. All indoor vendors should understand the airflow patterns in their spaces and design seating and foot traffic flow accordingly. IN same cases, ventilation may need to be augmented. And hard as it is for companies, but special cases like meat packing may need to cut their processing lines to allow for physical barriers and/or more physical distance between employees. Could be a good incentive for them to improve their ventilation to allow less spacing. Essential workers should not be sacrificed as has happened up to this point. This blog is more of a challenge to think about these things as opposed to highly detailed solutions. New reports are coming out daily with a lot of great ideas. I would very much like to see them summarized and mapped out in a much more coordinated fashion. I am very disappointed in how US agencies such as CDC, OSHA, Transportation, etc are not seemingly in the forefront. As always stay safe and sane. 4/24/2020 Welcome to Dan's Coronovirus Blog. Today's topic is the IHME Model. I do not understand how the IHME model works. Apparently this is an ongoing problem. A 2018 Korean paper (Biomed Res Int. 2018; 2018: 7236194) comparing IHME and WHO models contains this statement: Despite the in-depth review, there was “black box” <calculations-DB> that could not be explained specifically. IHME statements described "Gaussian fits". The problem is that mathematical distribution functions have no direct first principle design in growth. The correct math is X=X0e^ut where X=cases now Xo=starting cases u=growth rate (Mu) and t=time. The spread of infection mimics microbial growth. There is no support or the idea that the "growth" of infections shape should impact the "extinction" of infections shape other than the magnitude of total numbers prior to the retreat in daily number of cases. That is, the downcurve of cases is likely to be much slower than the upcurve, especially in a more open society where extreme Wuhan style lockdown is unlikely. If anyone has connection with IHME I am basically calling their whole model into doubt. Their expectation is cases to drop very low (10s per day) by June 1. I don't see anyway that happens. (And yes they have a confidence range but that value is NOT being used in any news or decision maker reporting). My model is built on the exponential equation. I did flip things to be a daily multiplier to get rid of the exponential equation to make it more accessible for folks without comfort with e math. I call that daily multiplier Rd (credit to tweets by Robert Williams @ifsBob). If there are 100 cases today and the multiplier is 1.3, then tomorrow there are 130 cases. That simple. Rest assured the exponential math is still there Ln(Rd)=u. I used Rd of 1.3 for rapid spread and 1.1 for initial social distancing. These were empirically determined from US data. I then looked to Italy and used 1.0 for a plateau period and 0.97 for the extinction term. Note that .97 per day works out to 0.8 for the week. Also, I am estimating Rt (effective transmission ratio) by Rd^5.6 with 5.6 days being the average transmission interval (CDC). Rd of 0.97 gives an Rt of 0.84. *Much more goes into the formal calc. I am at best a hobby epidemiologist--I've read several books on history of disease, but I did NOT stay at a holiday inn express last night). Note my model is not built on a calculated basis of efficiency of transmission, number of people encountered by an infected person, etc. Rather it is based on readily observable net rates from the US data and from Italy, which seems to be a good comparable for growth and extinction. From there I simply sum positives. To estimate deaths, I found a simple correlation that -7 days positives x 00.7=today's deaths. Since I started, IHME has added "Exponential splines" to their curves and a -8 day positive to death correlation term. On the chart are the days I adjusted Rd. Since I did this early April, the 1.3 and 1.1 were determined empirically (I did not predict them), from there I essentially eyballed Italy and made my own approximation for timing and magnitude of the multipliers as spread was slowed. Its been over two weeks now and I have not touched a thing. Please note my dates are when behavior changes show up, not the data of government policy changes. All data is from Covidtracking.com. To remain as a good quarantine partner to my fantastic spouse, I have not done much on a state by state basis. If I do too much of this I get quite cranky. I screamed at Lester Holt about the IHME model the other day. He did not even look up at me as he just continued to read the news).  |