Covid-19 in New York #3 (July 26)

Upstate New York was doing great for a while. From mid-June until July 9, there were only 1 or 2 active cases of Covid-19 in our county. Most surrounding counties were equally low.

I think people started to think the problem was all over. They visited out of state, and had Independence Day parties without masks or social distancing. As a result, Covid-19 surged back. This past week, the number of active cases in the county has ranged from 32 to 39. It’s almost as many as during the peak in late March. Surrounding counties also have spikes. Oops.

At the peak in March, there were 18 people hospitalized with Covid-19. That dropped to zero, most days in May and June. This week saw a maximum of 4, but it quickly went back to zero. There is much more testing now, so March and April probably had hundreds of hidden cases.

Fortunately, still no deaths in Ithaca and environs. Some nearby counties have experienced 10 to 60 fatalities, especially where the disease hit nursing homes.

On a national scale, the State Rt tracker is starting to show interesting wiggly curves for most states. Growth rates go up, until there are enough cases to make people panic and become more careful. Then growth rates decline, until people breathe a sigh of relief and go back to their old ways. Rinse, repeat.

Globally, cases are exponential again. The number of new daily cases is increasing with the same curve as cumulative cases. That’s how exponentials work.

This disease is not fading away just because the weather is hot. It probably will get worse in the Fall. Many vaccines are under development, but getting a well-tested one that’s both safe and effective is still many months off. So the big question is, how to have some semblance of a normal life as long as Covid-19 is still around?

The IHME Covid Projections site makes predictions for most countries and all US states. It now estimates deaths and infections up until November 1, calculated with and without universal mask adoption. The difference is huge, especially in places that are currently hit hard. Overall I think masks are probably the cheapest and easiest way to reduce transmission, and still carry on economic activity that is as close to normal as possible. There are other options too, but none better than blocking those pesky snot droplets right at the source.

Personally, I wear an N95 mask a lot. Definitely indoors in places with other people. Also outdoors when within 6 feet of anyone who is well-masked. I give 20 feet to anyone bare-faced, or wearing a chin-warmer. I saved seven N95s from a box left over from lead paint removal, and labeled one for each day of the week. They all have an exhaust port, but I put tape over it as a courtesy to other people. After 4 months of use the straps are starting to get ragged, but they still work. Hopefully they’ll last until replacements are back in stock.

Many people around here wear masks, and/or give other people plenty of distance. Unfortunately, there are also plenty of Covidiots who don’t give a crap. I asked one non-masked jogger to give me 6 feet as he charged at me on the sidewalk, and he just ran up close and laughed ha ha right in my face. So now I listen for footsteps and scramble out of the way. It’s safer to walk in traffic, rather than close to idiots/narcissists/sociopaths/whatever.

It’s really too bad that the US recommended against face masks for so long. Too bad that leaders didn’t set an example, for so long. The Feds and most states still haven’t figured out effective messaging, to get people to wear them (and wear them properly). I would suggest pushing a conspiracy theory that Bill Gates has cameras everywhere, and masks are the only way to escape surveillance. Its software uses nose and mouth, so make sure both are covered well.

The only good news is that the US approach is going to be great for epidemiologists. There are 50 different states doing different things, and getting different results. Thousands of cities and counties with assorted rules, and varying compliance rates. It’s going to be incredibly useful data.

Meanwhile, I am still stripping old asphalt and adding new metal roofing on my house. The project just hit 25% completion. I’ve never assembled scaffolding before, nor worked with such long sheets. It’s quite a challenge to remove 3.5 tons of decades-old shingle without creating a mess.

So far I have made almost every possible mistake. I guess that is pretty much how I’ve always learned construction. Or programming. Or anything else in life.

Maybe that’s what the USA also needs to do: make every possible mistake. Then the next pandemic will be easier.

Dennis Kolva
Programming Director
TurtleSoft.com

Covid-19: USA and the World (July 8)

I spent a couple days with Excel, futzing with John Hopkins data for Covid-19. The result is charts showing per-capita infections for the 90 most populous countries (confirmed cases per 100K people). They divide up fairly neatly into 5 groups.

First of all are countries that contained the virus quickly. Except for one city in China, their hospitals were not overwhelmed. Life is close to normal for them, now.

This group is about 27% of the global population, mostly in East Asia. That region had a scary experience with the SARS epidemic, so they knew just what to do for the Covid-19 outbreak: quarantines, contact tracing, testing. Local lockdowns when those weren’t enough. Almost everyone wore masks in public, even before the pandemic. They do help.

Next are countries with a low rate that is still growing. These are about 20% of global population. Almost all are Third World or close. That means the low numbers could be from lack of testing, rather than lack of disease. Australia (thicker line) is the outlier. They contained the outbreak for several months, but Covid-19 has recently started to increase again. It’s mid-winter in the Southern Hemisphere, which may be the culprit. That will also be the theme for other countries, later.

For the next three graphs, the vertical scale is compressed by 5x compared to the previous two.

The “getting serious” middle group has exponential growth, with infection rates that are just starting to be dangerous. Columbia (thick blue line) and Mexico (thick red line) are the worst. India (thick green line) is lowest per capita, but it may be under-reported. These countries make up about 36% of global population.

The fourth group had scary rates of infection in March to April, but they are mostly contained for now. Covid-19 snuck up on them, but all these countries responded well. All are First World countries, with 5% of global population.

Then there are the 15 countries already facing a serious impact from Covid-19, with infection counts that are still increasing. You might say these are the basket cases.

Worst of all is Chile (black line), which currently has 1,527 confirmed infections per 100,000 people. That’s over 1.5% of their population. It made the graph too tall for WordPress to handle, so I had to cut it off at the top. Peru (green) is #2 with .91% infected, Bolivia is #11, and South Africa (purple) is #12 and growing fast. Argentina is also exponential, but just below the cutoff I used. All five of those countries are in their winter seasons. That probably is a very bad omen for the Northern Hemisphere, looking ahead to Fall.

The next most bad-growing-worse countries got that way because of politics. USA (#3 red), Brazil (#4 yellow), Saudi Arabia (#6 orange) and Russia (#7 gray) all have autocratic rulers who started out denying that Covid-19 would be a problem. When proved wrong, they still didn’t do much to help fix things. Sweden (#5 light blue) tried a bold experiment, and didn’t shut down. They ended up with more infections, and an economy no better off than the rest of Europe.

All this stuff is just numbers, but it represents many people’s lives. Looking at that steep red line for the US makes me very angry, and very sad. How did we fuck up so badly? But I’d better stop now.

Dennis Kolva
Programming Director
TurtleSoft.com

Covid-19: Reopening (Jun 29)

New York State has been reopening gradually, with a minimum of 2 weeks between each phase. Ithaca entered Phase 4 on Friday, along with most of Upstate NY. Dine-in was allowed in Phase 3, but many restaurants are still takeout-only, or completely closed. All gyms are still closed, as are most bars. Large public events are still forbidden, and masks are required for all indoor public spaces. Outdoors, mask use seems to range from 0% to 70%, depending on location and time. I think it’s declining.

The Rt tracker site currently shows 33 states with increasing infection rates, and only 17 decreasing. New York had a low number through most of April and May, but it gradually inched up. Today it is exactly 1.0. If it stays there, the number of daily infections will remain the same indefinitely.

Since the current number reflects conditions from a couple weeks ago, it is very possible that NYS has reopened too quickly. The ideal balance between safety and economy probably was back at Stage 2 or 3. We will find out about that in a few weeks.

At least Covid-19 is close to contained around here. The county health department is doing almost 1500 tests a week, with only two of them positive on average. Nobody has been hospitalized here since May 29. Nobody local has died yet. Conditions are worse in the bigger cities within a few hours drive, but still tolerable. Even New York City is inching back from the brink.

Sadly, some other states are starting to become very dire. Most of the US reopened too quickly. Governors are starting to crack down, but they will soon find out what happens with exponential growth and a time lag. For example, right now the estimated Rt for Florida is 1.4. That means cases will almost triple before any impact shows, from remedies started today. Florida already has 9500 new daily cases, so it probably will get worse than New York City was in April, and soon.

It’s like watching a slow, enormous train wreck. Too bad it’s not just a train, but the whole frigging country.

Meanwhile, the big question locally is what happens after Cornell reopens this Fall. They just issued a 97 page report about it, but it leaves many details dangling. I think a lot of their plans ignore what students in their late teens and early 20s are like. The local economy is very dependent on the two colleges, so it’s going to be a very interesting ride.

I am pushing 70, so it makes sense to continue social distancing and mask-wearing, even though risks have declined. Most likely that will continue for at least another year. Masks suck, especially in hot weather, but they are a lot more comfortable than a respirator.

To cut down on exposure, the Turtlesoft office is currently open just one day a week. We probably will keep that schedule for most of the summer. Maybe longer. User support is still available by email, and usually by phone.

I spent the stimulus money on scaffolding. So I’m stripping 3 layers of ancient asphalt roofing off my house, and installing metal. It’s also a chance to finish up the exterior painting a bit more safely, and hang new gutters. After that, we’ll see. If QT seems plausible, at some point Goldenseal Pro will consume much more time again.

Dennis Kolva
Programming Director
TurtleSoft.com

Covid-19: Herd Immunity (Jun 16)

According to OpenTable, restaurant reservations in the US increased to 33% of normal, as of yesterday. It varies a lot between states: Rhode Island is close to 100%, while New York, Hawaii and DC are still under 10%. Those numbers are probably a decent indicator for general levels of reopening. The sharp dip yesterday was because it compares to Father’s Day 2019.

The Rt tracker website now shows 19 states with growth multipliers above 1. Arizona leads the pack, while most states in the Northeast are near the bottom. New York was #1 for new cases during most of April and May, but it fell to #8. The action has shifted south and west. Specific numbers vary with each update, but the trend has been consistent.

JUNE 19 UPDATE: the Rt tracker revised their calculation method today. They now show 26 states with growth rates greater than 1 (daily infections increasing). Several states are starting to look very scary.

Since economies are still ramping up, the best guess is that the growth rate will continue to increase. At some point, states with a growth rate much above 1 will run into trouble. Presumably they will then take action to reduce infections.

That means the Rt rate will probably hang out close to 1, pretty much indefinitely. For every infection that ends (via recovery or death), a new one will take its place (on average). Of course there will be large variations in different places.

In a previous post, I talked about containment. It can happen globally if every country reduces infections to zero, until the virus disappears. That’s what happened with SARS and MERS, the two previous coronavirus epidemics. Sadly, it seems very unlikely that containment for this one will ever happen in the US, nor globally. Covid-19 is just too well established. A few island nations have reached zero cases, but that’s still not great. They constantly will need to quarantine all visitors, or risk fresh outbreaks.

For a non-contained disease, the only other end game is herd immunity, which occurs when a critical mass of people are immune. If non-immune people are rare enough, then the disease gradually stops spreading. The amount of immunity needed depends on a lot of factors, but it’s usually between 60% and 90% of the population.

With herd immunity, the disease may eventually die out completely. It may stick around as a minor problem. Or it may return in surges, as each previous wave’s immunity fades away.

There isn’t anywhere with herd-level immunity to Covid-19 right now. New York City is probably the closest, with about 20% showing positive antibody tests. Elsewhere in the US, it’s rarely over 5%.

Doing some very quick math, if 3 months of infections made 5% immune, then it will take 45 months to hit 75%. The curve will be flat, but very wide.

Of course, vaccines are a great way to increase herd immunity very quickly, without all the sickness and death. In the US, roughly 60% of children and 45% of adults got a flu shot in 2018/9. For Covid-19, a recent survey showed 49% who plan to get a Covid-19 vaccination. 20% are unwilling, and 31% not sure.

That probably isn’t enough to attain herd immunity in one swell foop, but it’s close. After a vaccine is available and after half the anti-vaxxers get infected, the US will hit herd levels of protection.

Dennis Kolva
Programming Director
TurtleSoft.com

Exponential Growth #4: Containment (May 23)

In past posts I’ve talked about exponential growth when it’s fast and scary, and when it’s close to flat. But there’s also negative growth, with a multiplier of less than 1.

Right now, the Rt Tracker website shows all but four states with Rt like that, from Arkansas (.99) all the way down to Alaska (.63). If they can stay below 1 for long enough, Covid-19 eventually will reach containment.

Here is a chart of exponential growth rates less than one. It shows how the number of new cases of Covid-19 will decrease for each Rt multiplier. The lower the number, the faster the approach to zero.

Right now there are four states with Rt values under .82: Alaska, Hawaii, Vermont, and Montana. All have relatively small, isolated populations. They never had many cases to begin with, and are close to zero now. With local containment achieved, their biggest worry is new cases that come in from elsewhere.

The next lowest state is Connecticut, with an .83 multiplier. They had over 2000 new infections at the daily peak, but the average is about 600 now. At current rate of decline, it will take roughly 50 days to drop by a factor of 10 (to 60 new cases per day). Another 50 days gets it to 6 new cases. The theoretical curve never reaches zero, but with actual humans it’s possible to get there eventually.

Other states with higher Rt values will decline more slowly. Some will be very, very slow.

Exponential curves and Rt charts are pretty, but they are just theory. Actual containment depends on what people do each day: how much they stay home, how much they congregate, whether they wear masks. Just as important is the work of state and local health departments. They have battled all sorts of diseases over the past century, and this is just another for them.

To contain a disease, health departments do whatever it takes to reduce the infection growth rate to something less than one, then keep it that way.

Vaccines are the best way to contain a disease. Many folks are working on them for Covid-19. Next best is contact-tracing and quarantines. If those aren’t enough, then the only recourse left is massive social distancing. Economically, it’s an extremely painful option, but less bad than having many people suddenly sick and dying at the same time.

The ideal way to conquer a dread disease is to get global containment: already accomplished for smallpox, and almost completed for polio. Total containment is very hard work. Health workers must go into poor and war-torn regions and vaccinate enough people to reach “herd immunity”. It also requires plenty of contact-tracking and isolation until the last cases are completely gone. One sad consequence of Covid-19 is that it sets back the efforts to eradicate polio.

The Rt tracker site seems like a very useful tool. However, Rt is based on actual test results. It lags by at least a couple weeks, because it takes time for infections to develop, tests to be processed, and data to be entered into the pipeline. Today’s numbers reflect conditions from when state just started to reopen in early May. The social distance scorecard is probably the best way to predict the future, but it’s a very crude guide based on smart phone locations. It doesn’t adjust for mask use, indoor vs outdoor contact, or sanitation measures. Lately it rates most of the US at D or F, but I think reality is a grade or so better.

As social distancing relaxes, it will be interesting to see how much it affects the numbers. States will probably jump around with changes in weather, policies and people’s behavior. The risk is always there for an outbreak, with a sudden return to scary exponential growth. A single ‘super-spreader’ event can push any state to well above 1.

SARS and MERS were caught soon enough to be 100% contained. Covid-19 became too global, and it’s unlikely to ever reach full containment. Even with a vaccine. However, it can become like measles, influenza and other diseases that are controlled enough to not cause big catastrophes.

Dennis Kolva
Programming Director
TurtleSoft.com

Covid-19 and Construction #4 (May 16)

Two months ago, I first blogged about Covid-19. Since then, much has changed. Way more than I expected back then.

OpenTable has a spreadsheet for restaurant visits in 36 states, plus a few other countries. Here is their US data in chart form:

It only took two weeks to drop from normal (Mar 8) to zero (Mar 22). Many Governors shut down their states during that period, but the public was usually ahead of them by a few days. The collapse was close to simultaneous across the whole US, and also in Canada and most of Europe. Reopening started a couple weeks ago in a few states and countries, but it’s still very sparse.

What will Covid-19 do as social distancing relaxes? It may fade out for the summer as flu does. Maybe contact-tracing and moderate distancing will be enough to keep it controlled. Maybe there will be exponential outbreaks. Most people are taking it slow, which helps. Those who rush off to crowded bars and church services will be our guinea pigs.

Meanwhile, most of what I said back in March still makes sense. Here’s a slightly revised recap of my advice for construction companies:

  • Stagger work hours & locations. The less time people spend close to each other, the slower disease spreads.
  • Be clear with employees and subs. Send them home ASAP if sick, or don’t even let them come in. This might be time to start paying sick leave. Emphasize the need for testing and self-quarantine. Get a non-contact thermometer, and check people for fever.
  • Be clear with clients. If you work in client homes, let them know your plans. You might need to add plastic sheeting barriers, and sanitize more thoroughly at day’s end. Switch to outdoor work, if possible.
  • Take the usual precautions. Wash hands often. Sanitize surfaces that are touched frequently. Cancel group events. Practice social distancing. Listen to local & state health departments. Most are developing reopening guidelines now. The rules probably will be tweaked as time goes by.
  • Wear face masks. Back in March, CDC said not to use masks. Fortunately, their guidance has changed. I think masks may be the #1 way to stay safe, and still run a business. It’s worth elaborating.

Why wear face masks?

Covid-19 spreads mostly by respiratory droplets, which come in a wide range of sizes. Coughing and sneezing produce tons of them. Talking creates plenty. Even normal breathing makes some. The bigger droplets blow out a few feet, then drop quickly. They coat everything with virus gunk- that’s why it’s important to wash hands, and not touch your face.

The smaller droplets (aerosols) linger in the air. They can travel 20+ feet on air currents. Inhale, and they go straight into your airways and lungs. There is debate about how important aerosols are for Covid-19 transmission, but evidence is pretty good that they do cause many infections. Indoor spaces are more risky, especially when people are together there for hours. Air circulation (air changes per hour) makes a big difference.

Snot/saliva/ejected droplets from an infected person will have between 6 million and 2 billion viruses per cc (1 cc = 1/5 teaspoon). Fortunately, the droplets are very small, so only some contain a virus. Unfortunately, there are lots of them. Speaking produces 1,000 to 10,000 small droplets per second. Each cough makes a few thousand mostly bigger ones. Sneezes can make 40K, some of them huge.

Whether a droplet infects you is a matter of chance. Even if you inhale or ingest a virus, many of them get trapped in mucus and never reach a cell. Eventually they exit inside a booger. Others are killed by your body’s innate immune system, which has many anti-viral tricks. It takes a reasonable number of incomings, for even one to infect a cell.

Face masks work in both directions, to prevent that. Outbound, they catch virus droplets that infected people emit into the air and onto surfaces. They make other people safer. Inbound, an N95 removes 95% of aerosols, and almost all larger droplets. Surgical masks are less effective for inbound protection, but still pretty good. Even a bandana is better than nothing.

If everyone is masked, very little gets past the two different filters: one on the cougher, and one on the coughee. The risk of infection goes way, way down. Masks also reduce the odds of getting a really bad infection. I didn’t find any specific data for the effect of initial doses for Covid-19. However, almost all diseases are more deadly if you start with a lot of virus, rather than just a little.

It’s a matter of exponential growth. Once a virus invades a human cell, it starts producing duplicates. Those infect other cells, and it snowballs. The virus count zooms up inside you on a scary steep curve, just like it did globally in March.

Your adaptive immune system has many great ways to kill pathogens, but it takes time to ramp it up. If you started with one virus-infected cell, your defences probably can defeat the infection before it gets too big. You may not even notice any symptoms. Start with a few thousand, and you’ll be very sick. Start with a million or a billion, and you’ll probably die. That’s why Covid-19 kills young, healthy medical workers, especially when they don’t have proper PPE. They absorb a massive dose, the virus starts off strong, and it beats their immune response.

With masks all around, good sanitizing and careful air circulation, you probably can run safe construction projects. At least til Fall.

Dennis Kolva
Programming Director
TurtleSoft.com

The New Normal (May 10)

Some states are starting to reopen, and many residents are eager to get back to the old normal. It shows up in the data: half the states now rate an F on the social distancing scorecard, and only 5 beat a D+. In a month or two, we’ll find out if relaxing was a mistake.

On a personal level, here’s an informative guide to avoiding infection in a reopened world. There’s a lot to be said for not catching Covid-19. It may lose you some work time due to sickness or quarantine. You may die from it, or survive with reduced lung capacity and/or blood clot damage. Or, maybe you infect someone you care about.

On a larger scale, what happens next is hard to see. There are plenty of better experts out there, but here are some guesses on what the new normal will be like.

  • Covid-19 is here for the long haul. It escaped containment and is almost everywhere. Even if some regions stamp it out, someone without symptoms can bring it back in. The disease may reach “herd immunity” eventually, but that will take a few years.
  • Covid-19 may be permanent. Immunity to the 4 species of Coronavirus that cause common colds only lasts a year or two, so they keep circulating. Odds are good that Covid-19 becomes #5. If so, it gradually will become less lethal in the really long haul (decades to centuries). Until then, it will need a vaccine. Maybe an annual one, similar to influenza.
  • Developing a vaccine won’t be quick or easy. Trials have already started, but it takes time to ensure a new treatment is both safe and effective. Previous vaccines developed for Coronavirus diseases in pigs, chickens and dogs had problems. The stakes are higher for humans. After that, ramping production into the 100 millions will also be challenging. 18 months seems the best guess, give or take a few.
  • More testing is needed. Most tests done so far check for viral RNA in the deep part of your nose: it tells if you currently are infected. Simpler saliva tests are in the works. What’s also needed is antibody testing, to see who was previously infected. That includes folks who didn’t show any symptoms. Knowing the overall infection rate helps for planning, and helps catch outbreaks before they become deadly.
  • Still need some social distancing. Large group events of any kind will be risky until there’s a vaccine. People may need to wear masks routinely. The current social distancing measures pushed the R value below 1, but it needs to stay there for a long time. Hopefully there’s a sweet spot so life can go on without killing health workers or grandma.
  • Still need contact-tracing and quarantines. As long as the virus is still circulating, there’s always the risk it grows out of control. State and local health departments have dealt with a few dozen infectious diseases over the past century, and this will be one more that needs attention.
  • The economy will be weird for years. Money is just an arbitrary concept, so in theory we should be able to cancel a few months and get everyone squared up. In practice, nobody has any idea how to actually do that. This new recession isn’t like previous ones. There’s a lot to unravel.
  • The economy will never be the same.  Priorities will change. It’s hard to guess what 2022 will be like, but it won’t be 2019.
  • More Covids are coming. This is the third Coronavirus outbreak since 2003. It’s unlikely to be the last. The next one may spread faster or slower. It may be more lethal, or less.
  • Other pandemics are coming. Influenza sometimes gets deadly. There are always wildcard viruses like Ebola and Zika. Maybe something brand new. Humans are overpopulated and crowded. Nature tends to fix that with diseases.
  • It would help to be more ready. CDC and FEMA kinda dropped the ball, as did many others. We need better prep on all levels: personal, business, county, state, national, global. Fortunately, I think Covid-19 was bad enough to be a wake-up call for most people.

Dennis Kolva
Programming Director
TurtleSoft.com

Covid-19 in New York #2 (May 1)

A couple weeks ago I reported on the impact of Covid-19 on a few mostly-rural counties in upstate NY. Here’s a quick update.

Tompkins County (home of Ithaca, Cornell and TurtleSoft) is still doing well. 132 confirmed cases so far (1oo recovered, 32 active). Still 0 local deaths. The social distancing score has dropped from B+ to C+. However, most people wear masks outdoors now, and masks are required inside stores. That isn’t visible in cell phone location data, but probably makes a big difference.

Tioga County (former home of TurtleSoft) has gotten much worse. In the past week they went from 0 to 14 deaths: mostly in a single nursing home. 98 confirmed cases in a population half that of Tompkins. Social distancing rated a D. I went down there last weekend and nobody wore masks, despite state regulations. Going into the Mini-Mart to pick up a gas receipt felt like a trip back to February.

Steuben County (2 to the west) had it rough in the previous report, and it’s even worse there now. 231 confirmed cases, and 37 deaths in a population similar to Tompkins. Still D for social distancing.

New York State has started small-scale antibody testing (which shows past infection, even if no symptoms). Results are very preliminary, but they suggest that 20% to 25% of folks in New York City may have been infected already. In NYC suburbs it ran 10%, and only 2.5% around here. “Herd immunity” probably requires at least 60% infected, so everyone still has a ways to go.

The theme locally (and elsewhere) is that even rural areas have places that are crowded. Infections can run rampant there. Nursing homes are the most likely target, but prisons, meat processing plants and factories are also hot spots.

It’s a systemic problem, since employees that work in all those places are often poorly paid, often with no benefits. They probably live in more crowded housing that is prime for transmission. And of course, the high cost of healthcare in the US means they are less likely to call in sick, or get treated.

I have no idea how any of this will correlate with conditions in the rest of the US. Too many unknowns.

Dennis Kolva
Programming Director
TurtleSoft.com

Exponential Growth Part 3 (Apr 27)

In past posts I’ve talked about big exponential growth. The scary kind. Covid-19 was like that for most of the world in March. Multiplying by 2 or 3 every 4 or 5 days makes rapid changes.

Fortunately, thanks to social distancing, the pandemic settled down in April. People are still being infected, but in most places the number of new cases is close to constant. That means the Rt growth rate is about 1 (with some exceptions).

Here is a chart of small exponential growth rates.

Back when humans went to work, parties, restaurants and sports arenas, the Rt growth rate for Covid-19 was mostly between 2 and 3. Those would be almost vertical on this chart. The more horizontal curves come from a world that still has social distancing. Their shape depend on how much it reduces the infection rate. If the rate is more than 1, cases increase. If below 1, they gradually subside.

Small changes in the rate have a big impact. For example, if a region has hospitals currently at half-capacity, then an Rt of 1.05 overwhelms them in June. 1.04 hits crisis in July, 1.03 in August, 1.02 in October, and 1.01 postpones it til early 2021. 1.0 prevents it entirely.

One challenge is, there’s no way to know the current exact Rt number. The Rt Tracker website calculates a value for each state based on testing data and other factors, but their model is based on a lot of guesswork. The site include error bars above and below each estimate, to show how much uncertainty there is.

Even worse, there’s no way to know the impact each policy decision has on Rt. If everyone wears masks in public, the infection rate surely goes down: but how much is just a guess. Ditto for every other change in daily life. In a year or two there will be tons of data to help calculate impacts, but right now we’re on brand new terrain.

Even more worse, the system is complex and sensitive. The drastic changes in March dropped Rt all the way from 2.7-ish to 1.0. Small decisions like mask-wearing or opening restaurants could easily shift the Rt value up or down by several or many times .01. After a few months, that makes a big difference.

Governors, mayors and local health departments will make policy decisions. Individuals and business owners will make personal decisions. The net result will be some Rt number that won’t be known until infection data comes in, several weeks or a month later. That feedback delay can make the ride even bumpier.

If you’ve ever lost control of a vehicle on snow or ice, you probably experienced a feedback/delay loop. Skid to the right so you steer left, but there’s reaction time so you over-compensate. That leads to a few left/right cycles of increasing magnitude, until you’re backwards in a ditch.

Covid-19 will probably be similar over the next year or two. Odds are good there won’t be a whole giant pandemic again, but expect lots of little outbreaks. Local ones on the scale of factories or cities. Maybe some on the scale of states or countries or continents. The rules will need constant tweaking. Fasten your seat belts, folks.

Dennis Kolva
Programming Director
TurtleSoft.com

More Coronavirus Resources (Apr 21)

As a math nerd, I have a huge crush on Vi Hart. Usually she makes fun math videos, but she just released one that talks about how to unwind from Covid-19. The timeline is probably too optimistic, but otherwise it seems pretty sensible. Political will isn’t there yet to do it nationally, but maybe a few states can start that way.

The founders of Instagram just made a website that tracks RT, the current rate of increase for Covid-19 in each state. If it’s above 1, infections will increase exponentially. If below 1, they’ll decrease. Just one number for each state, with graphs of how it has changed over time.

Reddit has a few sub-reddits that cover the virus, with interesting links and lively discussions. r/Coronavirus is the most active, with many armchair epidemiologists. r/Covid19 is more science related, with research papers. r/CovidProjects is about mask production and similar pandemic efforts. For random, interesting science, r/Biology and r/Science are also good.

Science magazine has free access to its Covid-19 research articles. Research papers are hard to digest, but they usually have an abstract that is more readable.  Science also publishes articles for the general public, such this one about the way Covid-19 sickness plays out.

Meanwhile, I think the Internet has a big problem with bad information. Rumors and propaganda have always been out there, and people have always believed them. But, production values are better now. It’s easier to present compelling arguments that are wrong. Even dangerous. Bad info makes people do stupid stuff like burning cell towers.

The antidote is science. There are over 30,000 scientific journals out there: everything from Abnormal Psychology to Zygote. Most are extremely specialized, but the best of their research makes it into more general magazines like Nature, Science and Scientific American.  I devoured the latter as a kid, but moved on to the harder stuff.

Science research papers usually take a year or more to be published. The delay is mostly because of peer review. Other experts in the field check them over with a fine-tooth comb. The authors then revise and re-revise. Sometimes more experiments need to be run. Sometimes they need a complete do-over. It’s a grueling process, but the result is accurate info.

The system isn’t perfect, but it’s way more trustworthy than Facebook, Fox News or talk radio.  I’d highly recommend giving it a try. Things have sped up a bit for Covid-19, and serious papers are starting to come in.

Dennis Kolva
Programming Director
TurtleSoft.com