1 hour ago, birdguy said:

So, Alan, are you saying most of us are not immune? 

That's exactly the problem.  The "novel" in "novel coronavirus" means that it's a new kind of virus, and because most people haven't encountered it, they don't have antibodies for it.  Most of us are not immune. So anyone who encounters it is at risk of getting infected.

The reason that most people are not (yet) infected is that they haven't encountered it yet.  To catch it, two things need to happen.  You have to be in contact with the virus, and it needs to make the jump into you.

It can make the jump in various ways, and some of them are much more efficient than others.  The most efficient way is to come into contact with large amounts of virus in fluids (expressed when somebody coughs or sneezes).  That's the big risk to healthcare workers, because they're in close proximity to large numbers of people who are coughing and sneezing violently, or they're in direct contact with mucus from the mouth and nose.  That's why you see hospital workers in all that shielding - the big plastic face shields are designed to block big sprays of fluid.

After that comes aerosolized transmission - meaning that some of those fluids come out in microdroplets that stay suspended in the air for a long period of time.  So if you walked through a cloud of them and breathed them in, you'd stand a good chance of contracting the virus that way.

So far we're talking about catching it from people with symptoms.  But something else we've learned is that people can be infected for two weeks, give or take, without showing any symptoms.  During that time, the virus is multiplying rapidly, but hasn't yet caused enough damage that it leads to visible signs of illness. But those people are producing lots of virus and they can transmit it in the same ways - by coughing or sneezing.

In addition to all the coughing and sneezing, something else we all habitually do is touch our hands to our faces and mouths.  And when you do that, the virus can jump to you hand, and then to somebody else's hand (by, say, a handshake) and then to that person's mouth or nose (when that person touches his or her face).  So you've got transmission that way, both from people with symptoms and without.

The virus can also live on hard surfaces like metal, plastic or cardboard. So if I have the virus and touch my face and, instead of shaking your hand, I touch a door handle, and then you touch that door handle, and then your face, the virus can jump to you that way.  Tests show that the virus can live on cardboard for 24 hours and on metal and plastic for up to three days. That's not the easiest way for it to pass from one person to another - it's much more efficient when enormous quantities of the virus come out in those coughs or sneezes - but it can happen.

So, how hard is it to get the virus?  Pretty easy, given all these transmission paths.  It's a lot easier to get than, say, Ebola or HIV.  Those are deadly - much deadlier than the coronavirus (though HIV treatment now makes it manageable).  The reason is that those two aren't airborne - you have to have direct contact with body fluids.  Whereas the coronavirus is airborne - it travels much more easily.

Now, to the practical question - if I'm infected and I walk into your grocery store, how many people are going to get it?  The answer is that most of them won't.  They'll be too far away from me, or they won't touch what I touched.  Maybe there are a hundred people in the grocery store.  The statistics show that I might infect one (that's Rt=1) or two (Rt=2) or three (Rt=3).  Three would be a very high number.

So that doesn't sound like a lot - 97 or 98 or 99 of the people in the grocery store are going to go home and still be uninfected.  The problem comes in when the one or two or three newly infected people go on about their day - or, let's say, the 14 days that follow.  Because they're now starting to produce the virus, so they're becoming contagious.  And in every group of 100 people that they come in contact with, there's the same risk of infection.  Let's take the middle-of-the-road stat and say I infect two people.  One of those people goes from the grocery to the hardware store with 100 people in it and infects two more people.  Another goes to a restaurant with 100 people in it and infects two more people. So now, in the course of one morning and a couple of moves, my infection has infected six more people (two in the grocery store, two more in the hardware store and two more in the restaurant).  That's just in one day.  The same thing keeps happening for 14 days until all these infected people are symptomatic.  That's lots and lots of encounters, and lots of lots of infections.  That's how exponential growth works, and how very small numbers can quickly turn into a big problem.

In the real world, there could be fewer infections from each of those - maybe it's a lucky day and I don't infect anyone in the grocery store.  But I do infect someone in the park later.  And maybe one of those people I infected goes, not to a restaurant but a big family reunion where there's lots of embracing and sharing food and drinks.  That could give you ten infections, with the same growth rates.

Key point with all these people, again, is that no one is immune, because nobody's immune system has seen this thing before. 

What happens to these people?  Some of them might not ever develop symptoms.  A lot of them will get mild to moderate symptoms.  Only 10-15 percent will get sick enough to be in a hospital.  But that's a lot of people and those people are in for a rough ride.  Even so, only a percentage of those hospitalized people will die.  But again, those numbers add up.  And some people will die at home without ever getting to a hospital - and maybe not even be tested or counted.

Looking at the way it spreads, you can see why big cities have problems.  Put one infected person into a subway car with a few hundred people, and more getting on and off at every stop, and that's a lot of transmission.  But because of this one-infects-one or one-infects-two math, things can happen fast in low-density areas, too.  People gather differently in low-density areas, but they do gather.  They go to religious services.  They go to workplaces - look at the big clusters of cases in meat processing plants.  Those are in rural areas but at the plant, a few hundred people are jammed together without much if any protection.  Prisons are another big issue because of the way they jam people together.  And keep in mind that the people who work in those meat processing plants - or who are prison guards - then go home to their families, or they go to local businesses.  And that's how a rural area can get an infection going.

The thing that would give everybody immunity is an effective vaccine. That's what a vaccine does - it contains inactive bits of the virus, and when you administer it, the immune system gets a look at those proteins and starts encoding antibodies for it. 

Short of that, you have to rely on being able to treat the infection and reduce the impact of the symptoms.  Some of those are showing promise - Remdesivir seems to be worth watching.  But it's early days.  And the infection is so bad that treating it is a lot less good than preventing it.

The other thing you want to be able to do is test people - because if you know who's infected, you can be smarter about taking precautions, and maybe allow some kinds of activity.  But we'd need enormous amounts of tests to do that, and they'd have to be very accurate.  Right now neither of those things is the case - we can get there but it's not clear how long it'll take.

Until then, the most effective prevention is to keep people apart from each other so the virus isn't able to make those jumps.  Which, as we all know, is a blunt instrument that's causing a huge amount of economic damage.  But full economic activity takes us back to that one-infects-one or one-infects-two or one-infects-three math again.

Which is why people are saying that before you put people back into contact with each other, you have to have good information about the number of infections (14 days of declining cases seems to be the gold standard).  And you'll probably have to take precautions and allow some kinds of activities but not others - manufacturing but not masses of people gathering in arenas, curbside pickup but not in-store retail, takeout but not sit-down restaurants, or sit-down restaurants at half capacity so you can keep people apart from each other.  All to tweak that math.

It's really an ugly set of choices.

Hope this is helpful.

Edited April 21, 20206 yr by Alan_A

20 minutes ago, Nedo68 said:

Carefully, no matter what we do the virus is here and it will stay here for long, it will slowly blur into all regions, even with all the restrictions on.

...

 

But some good news too, an interesting read about Covid – 19 Deaths caused by pulmonary embolism?

 

Thanks - those are really interesting reports.  There's still a huge amount that has to be learned - they probably won't be treating covid six months from now the way they are today. The embolism study is worth watching (and a good example of how clinical medicine gets done).

It still floors me that HIV is now pretty much a chronic manageable illness - I remember the days when nobody believed anything like that would be possible.

 

Here's something an E-Mail friend sent me this afternoon.  I have a pulse oximeter and I use it to measure the oxygen in my blood the same time I take my blood pressure.  I also use it when exercising to monitor my pulse rate.  For those who don't know what a pulse oximeter is it is the thing they put at the tip of an index finger when you go into the doctor's office for a visit.  You can buy one at most sporting goods stores that have fitness equipment for about 20 dollars US. It measures the oxygen content in your blood as well as your pulse rate.  Mine ranges from 95 to 97 percent.  Knowing what the following says I know to call my doctor if it starts dropping.

By the time patients begin to feel short of breath, the pneumonia in the lungs has already progressed to dangerous levels. The key is detecting falling oxygen levels in the blood so that treatment can start before that happens, and avoid using ventilators if at all possible. That can be done with a simple non-invasive device, a pulse oximeter.

There are many commercial products available, and they can be purchased without a prescription — but their use should be done in

consultation with a doctor in order to make sure the user understands what the devices are showing them.

10 days before any doctor visit I take my blood pressure three times a day, morning, afternoon and evening, and log it on a chart along with my weight and my pulse oximeter reading.  That gives the doctor a better handle on my vitals than the reading taken during the visit.

These days when your doctor visits are over the telephone having your latest blood pressure and pulse oximeter readings would be valuable.

Noel

@birdguy (and everybody else) - as promised, here's a re-up of a quick glossary and set of links I posted about five weeks ago in another thread.  I've trimmed it back a bit since a lot of the examples I linked to are now way out of day.  The reason I'm re-posting is to give some links to a couple of basic terms and "scorekeeping" numbers that make it easier to follow all the covid reports, whether they're in the news or in academic papers or anything else that people cite:

Quote

 

These are some basic numbers to track if you want to see how an epidemic is behaving:

1. The percentage of the population that's infected.  Almost impossible to gauge right now in covid because of the number of asymptomatic cases and because tests are inconsistent and unreliable (and there just aren't enough of them). 

2. The infection fatality rate (IFR) and the case fatality rate (CFR).  The IFR tells you how many infected people die of the disease.  The CFR tells you how many people with symptoms ("cases") dies of the disease. The numbers in the case of covid are estimates because of the problem with item 1 - we don't know the number of infected people.  IFR is very difficult to gauge here. CFR figures are usually based on confirmed cases - people with symptoms who test positive.  If people are dying without getting tested (e.g. dying at home), then IFR and CFR go higher.  If many more people are infected than we know about, and we're capturing all the deaths then IFR and CFR go lower. For context: the 1918-19 flu pandemic had a case fatality rate of 2.6 percent.  The case fatality rate of seasonal flu is 0.1 percent.  If the CFR for covid turned out to be 1 percent, it would be less than half as deadly as the 1918 pandemic but ten times deadlier than the seasonal flu. IFR and CFR are useful because they help you find out how deadly a disease is in its own terms.  Seasonal flu kills a lot more people than covid because so many people have seasonal flu.  Covid is just starting to spread.  But many more people who get covid die of it. The additional thing to note about CFR is that full-population figures only tell you so much - you have to look at the numbers for different age cohorts. CFR for COVID-19 starts shooting way up for people over 60. 

3. The basic reproduction number, rendered as R₀ ("R-zero" or "R-naught" - the number that tells you how many new infections are produced by each individual infection.  The reproduction number is the indicator of how contagious the disease is. It's what produces that one-infects-one or two or three math I was talking about in my post just above.

4. Doubling time - the amount of time it takes for the number of cases to double.  That gives you the picture of how fast the disease is spreading in a population.  Hospital planners need to watch it to account for capacity - which is a major issue.  In the case of covid, doubling time is very fast and reflects exponential growth - defined here. An excerpt: "The growth of a bacterial colony is often used to illustrate it. One bacterium splits itself into two, each of which splits itself resulting in four, then eight, 16, 32, and so on. The rate of increase keeps increasing because it is proportional to the ever-increasing number of bacteria. Growth like this is observed in real-life activity or phenomena, such as the spread of virus infection, the growth of debt due to compound interest, and the spread of viral videos."  

If you take those numbers into account, you'll have a handle - maybe a rough one, but still a handle - on how many people are infected, how many will die (and how sick the rest will get), how contagious COVID-19 is, and how fast it's spreading.  And you'll be inoculated (sorry!) from bad numbers - like the people who want to say that seasonal flu is much worse because it kills more people.  Yes it does, but that's not the relevant issue.  What matters is how quickly covid is getting out of hand.

 

As always, hope this is helpful. 

For excellent explanations of some issues with these numbers as they apply to covid - and for up-to-date stats - I recommend the Our World in Data coronavirus page  It's one of the best data sites out there.

9 minutes ago, birdguy said:

Here's something an E-Mail friend sent me this afternoon.  I have a pulse oximeter and I use it to measure the oxygen in my blood...

That's very good advice.  You hear stories about how fast the infection hits people once it gets into the lower lungs - they're OK or maybe just a little short of breath in the morning, they start having huge difficulty breathing in the afternoon, and by evening they're on a ventilator.  Monitoring blood oxygen levels could give you some early warning.

I'm sure before long it'll be common to be able to transmit the results to your doctor in real time. Telemedicine seems to be here all of a sudden - one of a lot of changes we're going through.

Alan, So far I've seen nothing about regional effects.  Cities versus urban areas.  Geography and climate.  Population density.

One of the reasons I am behaving as a contrarian is because I look at the threat not from Italy or New York but from a small city in the desert with very low humidity and very few cases of COVID-19.  

Roswell is an island in SE New Mexico with just 21 (0.03% of the population) cases surrounded by counties with 0 to 3 cases and no fatalities.  It's hard for me to relate to New York and the one-size-fits all mentality applicable to the worst case scenarios.

It might happen here.  But so far the sky is not falling and the sun shines every day.

Has there been anything written along those lines?

Noel 

Edited April 21, 20206 yr by birdguy

@birdguy Get one!
A pulse oximeter was invaluable to me during the worst part of having the illness.

My %SpO2 never dropped below 95. So even though I felt rather short of breath and my resting heartrate was well above usual, it was a relief to know that it wasn't serious enough to warrant medical attention.
My friend who was hospitalised was taken in by ambulance with a reading of 89 by the paramedics. Went onto a ventilator the next day.

The biggest concern that is emerging is the potential lack of immunity. As both MartinRex007 and Alan_A pointed out in their earlier posts on p.76, the immune response to respiratory infections is poor.
There's early evidence to suggest that a significant number of people who had the illness did not stimulate sufficient antibodies to prevent them from contracting Coronavirus again in short order.

https://www.scmp.com/news/china/science/article/3078840/coronavirus-low-antibody-levels-raise-questions-about

https://time.com/5810454/coronavirus-immunity-reinfection/

That would be very worrying as it has ramifications as to what is the safe way to get economies running to at least some level of usefulness.
Hopefully, these turn out to be spurious results and higher numbers of recovered patients tested will invalidate them.

48 minutes ago, birdguy said:

Alan, So far I've seen nothing about regional effects.  Cities versus urban areas.  Geography and climate.  Population density.

...

Has there been anything written along those lines?

 

There's not a lot out there yet - everybody's watching that space. I don't think we know yet what's going to happen.

This article is a pretty good roundup of what people are concerned about.  It mainly discusses the factors that might create risks - older population, distance from medical care, limited local healthcare resources, people driving back and forth to cities for medical care and other reasons.  And also the case clusters that are already out there, like in the meat packing plants.

The thing we'll have to watch for is increasing numbers of cases. That Johns Hopkins county-by-county drill down will be useful for that.

This site, which is run by the federal government, looks like it'll be a good resource, but right now it's mainly a bunch of links to general information.

It does include a short article on rural HIV - which is another condition that we mostly think of as urban but a couple of waves have gone through rural areas.

The risk of rural covid is going to get a lot of attention - I'll keep digging and see what else I can come up with.

EDIT: Here's one more.  Not sure if you like Politico as a source but the reporting is pretty straightforward - mainly interviews with rural health officials.  Like the Healthline piece, it's about things that concern them, not things that are happening yet.

Edited April 21, 20206 yr by Alan_A

@ birdman

All the studies to date suggest that only a small percentage of most populations have currently had covid19.

Three in a hundred in Netherlands (4000 deaths)  one in  three hundred in Austria ( 500 deaths) and according to the Stamford study four in a hundred in Santa Clara ( 90 deaths however there are some flaws in that last study).

As one in a thousand people in New York have died  we can conclude that a great deal more people there have been exposed. 

When talking about lockdowns you keep coming back to your risk which is the wrong way of looking at it.

Consider voting. Logically there  is no point in any one person voting as their vote will never be the deciding vote and so the outcome will be the same if they hadn’t bothered to vote.  However society functions better if we all ignore that and behave as if our vote matters and go and vote as the majority then elect the candidate that they want.

In the same way the lockdown isn’t to protect you.  There are only currently a very small number of people in Roswell who are currently symptomless with the virus and you are therefore unlikely to either be one of them or meet one of them.  But there are almost certainly some people in Roswell who are infected and because this disease is very infectious each one will infect 3 others and each of those will infect 3 others and very quickly a lot of people will have it.  

The idea of the lockdown is that if everyone follows the rules then the people who do have it (whoever they are) will also follow the rules and so the virus doesn’t get passed on. Now if everyone decides that it is silly and doesn’t do it then the virus will get passed on.  If everyone follows the rules then society as a whole benefits.
 

 

Sadly, other than this year's massive deviation from the average seasonally adjusted mortality rate from ALL causes, the remaining COVID-19 data is biased by the lack of testing. And for all we know, people who are either asymptomatic or have recovered from mild cases may not show high enough antibody levels to show up in some of those limited tests. And even if someone tests positive for Coronavirus antibodies we don't know what level confers lasting immunity.

On the french aircraft carrier we know that almost half the crew tested positive with the antigen test.  
The Austrian population sample used the antigen tests on a statistically selected group from which they  inferred the population infected to date.  So the % infected cannot be more than twice what they calculated.

New York also sets a minimum IFR of 0.1% with new infections still occurring.

The number of people one person infects (R) can be calculated from the rate at which the numbers change so it’s at least 3.

The % of the population that needs to be infected can be calculated from R    So if R is 3 then it’s just over 66%.

If you think about it if a person passes it on to 3 others and 66% are immune then 2 of the 3 it would have been passed onto would be immune and it only gets passed on to 1 other person.   If slightly more than 66% are immune then it dies out as each person passes it on to less than one other.

 

 

 

 

 

 

 

 

 

58 minutes ago, jabloomf1230 said:

the remaining COVID-19 data is biased by the lack of testing.

Agree.

Good summary here of the issues in testing - and the problems with how testing data is reported.

1 hour ago, birdguy said:

Alan, So far I've seen nothing about regional effects.  Cities versus urban areas.  Geography and climate.  Population density.

One of the reasons I am behaving as a contrarian is because I look at the threat not from Italy or New York but from a small city in the desert with very low humidity and very few cases of COVID-19.  

Roswell is an island in SE New Mexico with just 21 (0.03% of the population) cases surrounded by counties with 0 to 3 cases and no fatalities.  It's hard for me to relate to New York and the one-size-fits all mentality applicable to the worst case scenarios.

It might happen here.  But so far the sky is not falling and the sun shines every day.

Has there been anything written along those lines?

Noel 

I think the purpose of the lockdown is simply to slow down the spread of the virus, otherwise we risk an exponential growth in infections and then things get completely out of control.  It also buys the doctors some time to learn more about the virus and develop treatments to prevent deaths.

Again, some folks seem to suggest that we must do whatever the doctors say, and if that means we shut down for another 3 months then so be it.  My argument is that we simply can't do that as it would cause much more harm than 1% of the population dying, as awful as that would be. 

If this disease were something like Ebola which kills an average of 50% of those infected, and could be transmitted easily by air between humans like Covid-19, then I would say we have to shut it all down for as long as it takes, otherwise we risk losing half the population which would pretty much destroy us.  Fortunately, Covid-19 is far less lethal.

I believe that most areas can begin to open back up without greatly increasing the number of infections as long as everyone practices the safeguards against infection like washing hands frequently, maintaining a safe distance from others, and wearing a mask.

Folks have to remember that when this started infecting people on a large scale, most people were not aware of it so they weren't taking precautions like they are now.  I think that our cautious behavior will go a long way in defeating this virus.

 

Dave

29 minutes ago, dave2013 said:

Again, some folks seem to suggest that we must do whatever the doctors say, and if that means we shut down for another 3 months then so be it.  My argument is that we simply can't do that as it would cause much more harm than 1% of the population dying, as awful as that would be. 

And yet the data shows that when you act to prevent fatalities, the economy does better. 

This is a summary of the paper I linked to before.  And here's another summary that presents some of the data. And news coverage here.

We really - and I include myself in this - need to stop debating public health vs. the economy as though it's an either-or.  It's not. It's really a complicated set of interactions.  A more widespread or longer-lasting pandemic damages the economy.

And all of us should also keep in mind that "restarting the economy" isn't going to be like throwing a switch.  What's more likely is a gradual restart of some activities - with continued economic damage because a lot of activity will still be restricted, and with the chance that we'll have to dive back into lockdown if there are new outbreaks or a second wave. The safe distance guidelines interfere with a lot of business, from restaurants to retail to manufacturing (i.e. how many people can you safely have on your factory floor?)  It's not going to be as simple as wearing a mask and getting back to (otherwise) normal.

To get a bigger, more effective economic restart, we should all be pushing hard for a massive testing and contract-tracing program.  If you can test and monitor, you can open up more activity.  If you can't, it's Russian Roulette. 

 

Edited April 21, 20206 yr by Alan_A

We now pause for a bit of humor...