Author Topic: Probability that covid will become endemic  (Read 8240 times)

clutch

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Re: Probability that covid will become endemic
« Reply #10 on: November 17, 2020, 01:02:26 PM »
Even if it becomes endemic, things will return to normal. Both the transmission rate and fatality rate will continue to lower (with vaccine and better treatment), making this another type of the common flu. Not to mention, we will reach some form of herd immunity -- as it did with (and ended) the Spanish flu. We haven't changed much of our behaviors because of the flu.

How is the transmission rate, that is, R0, going to go down for mutations of Covid-19 coronavirus with vaccine and better treatment. 

Flu has an R0 of about 1.3, i.e. one person can spread it to 1.3 people on average.
Covid-19 coronavirus strains have an R0 as high as 5 or higher.

Do we know of other ways of lowering R0 for Covid-19 strains other than behavior change?  We cannot say with 100% certainty that herd immunity will continue to provide immunity for mutated strains of Covid-19.  We do know that herd immunity does not provide immunity for mutated strains of flu coronaviruses.

Vaccines. The transmission rate will go lower if more people are immune to it. Isn't that obvious?

If the virus mutates and presents a serious threat again, I'm sure that we will develop another vaccine that works.

Hence, my question at the start of the thread, i.e. what is the probability that we would need a vaccine every year?  So, you agree that the probability of that is non-zero?

Yes, but it won't change our behaviors to the point that the industries you pointed out will significantly change.

We get flu vaccines every year.


LearningMachine

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Re: Probability that covid will become endemic
« Reply #11 on: November 17, 2020, 01:18:58 PM »
Even if it becomes endemic, things will return to normal. Both the transmission rate and fatality rate will continue to lower (with vaccine and better treatment), making this another type of the common flu. Not to mention, we will reach some form of herd immunity -- as it did with (and ended) the Spanish flu. We haven't changed much of our behaviors because of the flu.

How is the transmission rate, that is, R0, going to go down for mutations of Covid-19 coronavirus with vaccine and better treatment. 

Flu has an R0 of about 1.3, i.e. one person can spread it to 1.3 people on average.
Covid-19 coronavirus strains have an R0 as high as 5 or higher.

Do we know of other ways of lowering R0 for Covid-19 strains other than behavior change?  We cannot say with 100% certainty that herd immunity will continue to provide immunity for mutated strains of Covid-19.  We do know that herd immunity does not provide immunity for mutated strains of flu coronaviruses.

Vaccines. The transmission rate will go lower if more people are immune to it. Isn't that obvious?

If the virus mutates and presents a serious threat again, I'm sure that we will develop another vaccine that works.

Hence, my question at the start of the thread, i.e. what is the probability that we would need a vaccine every year?  So, you agree that the probability of that is non-zero?

Yes, but it won't change our behaviors to the point that the industries you pointed out will significantly change.

We get flu vaccines every year.

Thanks clutch, it is a very fair point that we get flu vaccines every year, and don't worry about flu that much while going on about our lives.

Let's also assume that we will eventually be able to treat covid-19 without requiring hospitalization for a big percentage of people.

One difference that will likely stay is that Flu coronaviruses have an R0 of about 1.3, i.e. one person can spread it to 1.3 people on average, while Covid-19 coronavirus strains have an R0 as high as 5 or higher.

Where that difference might play out is in some people's behavior while they are waiting to get the vaccine for new strains.   With flu coronavirus strains, because the transmitability is lower, we don't worry too much about the risk and go about our usual behaviors.   With Covid-19 coronavirus strains, because of higher risk of catching it, our behaviors might be somewhat more constrained than with flu while waiting for vaccine for new strains of the year.

Look at some of our behaviors currently while we are waiting for the Covid-19 vaccine.  I agree with you once treatment without hospitalization is possible for a big percentage of people, we probably won't restrict our behaviors as much as now while waiting for vaccine for new Covid-19 strains, but we might not relax our behaviors all the way to how we act while waiting for flu vaccines because of increased transmitability with Covid-19 coronavirus strains.

If the probability of Covid-19 coronaviruses becoming endemic like flu coronaviruses materializes, there will probably be some effect on our behaviors longer term, which will probably have some impact to whether 100% of people will go back to working from office 100% of the time.
« Last Edit: November 17, 2020, 01:22:11 PM by LearningMachine »

LearningMachine

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Re: Probability that covid will become endemic
« Reply #12 on: November 17, 2020, 01:35:12 PM »
Which one of the below are you saying?
  • (a) 100% certainty that Covid-19 coronavirus will not mutate, unlike the flu coronaviruses, or
  • (b) 100% certainty that the same vaccine we get once for Covid-19 coronavirus will be able to provide immunity against all mutations of Covid-19 coronavirus, unlike the vaccine for flu coronaviruses.

https://www.biorxiv.org/content/10.1101/2020.11.15.383323v1

100% certainty that Covid-19 will mutate but at a much slower rate than influenza viruses (we should be grateful this isn't "just the flu").

To simplify, let's assume the rate of mutation is related to mutations during the following:
1. Replications within a host (human or animal)
2. Jumping between hosts
3. Jumping between species

This suggests that rate of mutation will be highest at the peak of the pandemic when the virus is replicating rapidly in people and jumping rapidly between hosts. We've had perhaps trillions of replications, yet vaccines are showing 90% efficiency. This shows that the virus is not mutating rapidly (which is also shown in genetic tracing).

You could foresee some random mutation that allows Covid-19 to evade the vaccine, but the probability is related to the number of mutations. So the likelihood of a dangerous mutation occurring after June 2021 is much lower than one occurring in 2020.

Edit to add: So that suggests you won't need a yearly vaccine solely due to mutations. You might still need one for waning immunity, but the preprint above suggests immunity could be reasonably long-lived.

Thanks KCLarkin, this is helpful. 

Based on this, looks like probability of Covid-19 coronaviruses becoming an endemic is much lower than flu coronaviruses.
« Last Edit: November 17, 2020, 01:42:48 PM by LearningMachine »

clutch

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Re: Probability that covid will become endemic
« Reply #13 on: November 17, 2020, 04:13:29 PM »
Thanks clutch, it is a very fair point that we get flu vaccines every year, and don't worry about flu that much while going on about our lives.

Let's also assume that we will eventually be able to treat covid-19 without requiring hospitalization for a big percentage of people.

One difference that will likely stay is that Flu coronaviruses have an R0 of about 1.3, i.e. one person can spread it to 1.3 people on average, while Covid-19 coronavirus strains have an R0 as high as 5 or higher.

Where that difference might play out is in some people's behavior while they are waiting to get the vaccine for new strains.   With flu coronavirus strains, because the transmitability is lower, we don't worry too much about the risk and go about our usual behaviors.   With Covid-19 coronavirus strains, because of higher risk of catching it, our behaviors might be somewhat more constrained than with flu while waiting for vaccine for new strains of the year.

Look at some of our behaviors currently while we are waiting for the Covid-19 vaccine.  I agree with you once treatment without hospitalization is possible for a big percentage of people, we probably won't restrict our behaviors as much as now while waiting for vaccine for new Covid-19 strains, but we might not relax our behaviors all the way to how we act while waiting for flu vaccines because of increased transmitability with Covid-19 coronavirus strains.

If the probability of Covid-19 coronaviruses becoming endemic like flu coronaviruses materializes, there will probably be some effect on our behaviors longer term, which will probably have some impact to whether 100% of people will go back to working from office 100% of the time.

I can understand your point of view better now. I do think working from home more (not 100%, but >0%) will be permanent now. Besides preventing the spread of diseases, there are many benefits that people have now recognized and will convince the companies to allow people to work from home more. I'm invested in a number of enterprise software/digitization companies for this reason.

Regarding the transmission rate, I think that R0 for the typical flu is much lower because the larger portion of the population has already built immunity and some of them are vaccinated. If the same virus was novel like Covid-19, I'm pretty sure the R0 would be higher, although not high as Covid-19.

LearningMachine

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Re: Probability that covid will become endemic
« Reply #14 on: November 18, 2020, 10:49:09 PM »
Thanks clutch, it is a very fair point that we get flu vaccines every year, and don't worry about flu that much while going on about our lives.

Let's also assume that we will eventually be able to treat covid-19 without requiring hospitalization for a big percentage of people.

One difference that will likely stay is that Flu coronaviruses have an R0 of about 1.3, i.e. one person can spread it to 1.3 people on average, while Covid-19 coronavirus strains have an R0 as high as 5 or higher.

Where that difference might play out is in some people's behavior while they are waiting to get the vaccine for new strains.   With flu coronavirus strains, because the transmitability is lower, we don't worry too much about the risk and go about our usual behaviors.   With Covid-19 coronavirus strains, because of higher risk of catching it, our behaviors might be somewhat more constrained than with flu while waiting for vaccine for new strains of the year.

Look at some of our behaviors currently while we are waiting for the Covid-19 vaccine.  I agree with you once treatment without hospitalization is possible for a big percentage of people, we probably won't restrict our behaviors as much as now while waiting for vaccine for new Covid-19 strains, but we might not relax our behaviors all the way to how we act while waiting for flu vaccines because of increased transmitability with Covid-19 coronavirus strains.

If the probability of Covid-19 coronaviruses becoming endemic like flu coronaviruses materializes, there will probably be some effect on our behaviors longer term, which will probably have some impact to whether 100% of people will go back to working from office 100% of the time.

I can understand your point of view better now. I do think working from home more (not 100%, but >0%) will be permanent now. Besides preventing the spread of diseases, there are many benefits that people have now recognized and will convince the companies to allow people to work from home more. I'm invested in a number of enterprise software/digitization companies for this reason.

Regarding the transmission rate, I think that R0 for the typical flu is much lower because the larger portion of the population has already built immunity and some of them are vaccinated. If the same virus was novel like Covid-19, I'm pretty sure the R0 would be higher, although not high as Covid-19.

My understanding is that Covid-19 coronavirus strains are more contagious than flu coronavirus strains because former survive outside the host longer than latter. 

samwise

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Re: Probability that covid will become endemic
« Reply #15 on: November 20, 2020, 09:17:16 PM »
Passing on from a health expert.

ď95% efficacy is the stuff of dreams, where you dream about eradication of the disease rather than just containment. E.g. MMR vaccines are 97% efficacy against measles, and the disease hardly exists anymore. And thatís when measles has R0 of over 15. ď

So depending on how long immunity lasts and how fast the virus mutates, it might not become endemic.

Cigarbutt

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Re: Probability that covid will become endemic
« Reply #16 on: November 21, 2020, 01:56:14 PM »
Passing on from a health expert.
ď95% efficacy is the stuff of dreams, where you dream about eradication of the disease rather than just containment. E.g. MMR vaccines are 97% efficacy against measles, and the disease hardly exists anymore. And thatís when measles has R0 of over 15. ď
So depending on how long immunity lasts and how fast the virus mutates, it might not become endemic.
The following is submitted for analytical purposes and may have investment implications but political aspects have been sterilized, to the extent possible.

FWIW, I think Covid-19 is likely to become endemic, within a year or two, but it will likely be an immaterial kind of endemicity. Below are the key factors considered as well as references used.

-Availability of effective vaccines (% and strength of response, duration of protection)
This looks promising but longer term duration is still unknown. How many in the population (at-risk and as potential spreaders) will take them is a limiting factor if vaccination rates donít reach certain levels. Also, itís still unclear if older and at-risk cohorts will be able to build and maintain sufficient immunity levels (available, on demand for antibodies or from ďmemoryĒ cells). The typical FDA agreement includes to complete follow-up studies for safety and efficacy for at least two years.

-Virus characteristics
Many respiratory viruses are endemic, including the four well known common cold (beta family) coronaviruses. Longer term studies point to a very real risk of endemicity. More virulent CVs (SARS and MERS) seem to be associated with longer and more robust immunity. Covid-19 is kind of hybrid so common sense would indicate that endemicity risk is real.
CVs tend to mutate less than influenza for instance (because of a very unusual and fascinating proof-reading mechanism during replication and specific to this class of RNA viruses) but this is both good and bad. The good part indicates that covid-19 will tend to be slow to genetically escape existing immunity but the bad part indicates that when a new genomic form with new characteristics is reached, this stable form may bear less favorable characteristics for the host (including for immunity) and may persist longer.
Whatever residual immunity (natural or vaccine-related), reinfections are likely to be less severe which opens the eventual possibility of eradication to the same degree that it opens the door to low grade endemicity.

-Population and environmental characteristics
With the virus impact becoming less significant and with less public awareness or media attention, non-pharmacological measures will tend to be abandoned, not enough to cause major and widespread outbreaks over time but enough to allow endemicity in many populations. The virus has become truly global and the world has grown smaller.
Seasonal and various environmental factors (for most areas of the world) may become a feature for Covid-19, following what other common cold coronaviruses have become over time.
-----
So, on a weighted basis, itís likely that Covid-19 reservoirs will persist over time but are unlikely to trigger material events on a global basis.

For references, I was lucky to be able to listen to a very strong presentation 8 days ago by various Ďexpertsí. One of the presentations dealt specifically with immunity, reinfection risks and vaccinations. She covered, in a few minutes, most of the relevant research, some of which is mentioned in the CDC link found below (pages 12-22 for post infection immunity, pages 23-32 for reinfection risk). The study mentioned on page 28 is somewhat interesting (design, implications, despite limitations). Also found below is a link to a site monitoring progress on the vaccine front. The amount of human capital involved is mind boggling. The people involved have obvious financial incentives but there is an unusual amount of drive, especially in smaller operations.
https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2020-10/COVID-Wallace.pdf
https://covid19.trackvaccines.org/vaccines/

LearningMachine

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Re: Probability that covid will become endemic
« Reply #17 on: November 21, 2020, 04:21:50 PM »
Passing on from a health expert.
ď95% efficacy is the stuff of dreams, where you dream about eradication of the disease rather than just containment. E.g. MMR vaccines are 97% efficacy against measles, and the disease hardly exists anymore. And thatís when measles has R0 of over 15. ď
So depending on how long immunity lasts and how fast the virus mutates, it might not become endemic.
The following is submitted for analytical purposes and may have investment implications but political aspects have been sterilized, to the extent possible.

FWIW, I think Covid-19 is likely to become endemic, within a year or two, but it will likely be an immaterial kind of endemicity. Below are the key factors considered as well as references used.

-Availability of effective vaccines (% and strength of response, duration of protection)
This looks promising but longer term duration is still unknown. How many in the population (at-risk and as potential spreaders) will take them is a limiting factor if vaccination rates donít reach certain levels. Also, itís still unclear if older and at-risk cohorts will be able to build and maintain sufficient immunity levels (available, on demand for antibodies or from ďmemoryĒ cells). The typical FDA agreement includes to complete follow-up studies for safety and efficacy for at least two years.

-Virus characteristics
Many respiratory viruses are endemic, including the four well known common cold (beta family) coronaviruses. Longer term studies point to a very real risk of endemicity. More virulent CVs (SARS and MERS) seem to be associated with longer and more robust immunity. Covid-19 is kind of hybrid so common sense would indicate that endemicity risk is real.
CVs tend to mutate less than influenza for instance (because of a very unusual and fascinating proof-reading mechanism during replication and specific to this class of RNA viruses) but this is both good and bad. The good part indicates that covid-19 will tend to be slow to genetically escape existing immunity but the bad part indicates that when a new genomic form with new characteristics is reached, this stable form may bear less favorable characteristics for the host (including for immunity) and may persist longer.
Whatever residual immunity (natural or vaccine-related), reinfections are likely to be less severe which opens the eventual possibility of eradication to the same degree that it opens the door to low grade endemicity.

-Population and environmental characteristics
With the virus impact becoming less significant and with less public awareness or media attention, non-pharmacological measures will tend to be abandoned, not enough to cause major and widespread outbreaks over time but enough to allow endemicity in many populations. The virus has become truly global and the world has grown smaller.
Seasonal and various environmental factors (for most areas of the world) may become a feature for Covid-19, following what other common cold coronaviruses have become over time.
-----
So, on a weighted basis, itís likely that Covid-19 reservoirs will persist over time but are unlikely to trigger material events on a global basis.

For references, I was lucky to be able to listen to a very strong presentation 8 days ago by various Ďexpertsí. One of the presentations dealt specifically with immunity, reinfection risks and vaccinations. She covered, in a few minutes, most of the relevant research, some of which is mentioned in the CDC link found below (pages 12-22 for post infection immunity, pages 23-32 for reinfection risk). The study mentioned on page 28 is somewhat interesting (design, implications, despite limitations). Also found below is a link to a site monitoring progress on the vaccine front. The amount of human capital involved is mind boggling. The people involved have obvious financial incentives but there is an unusual amount of drive, especially in smaller operations.
https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2020-10/COVID-Wallace.pdf
https://covid19.trackvaccines.org/vaccines/

Thanks Cigarbutt, this is super-helpful.  If the covid-19 reservoirs persist over time, even if it doesn't cause a material event on a global basis, would it impact behavior of some percentage of the population, e.g. not travel as much as they did pre-covid, not go to places with lots of people as much, etc.?

Maybe the behavior change will depend on the perceived probability of risk, and how readily available are the alternatives to taking risk, i.e. working from home, ordering everything online, etc.?  If the perceived risk is as high as it was (1) getting on 737 Max right after two crashes, maybe some would pick an alternative if available but if it as low as (2) driving a car, maybe people will accept.   Wondering where on the spectrum between #1 and #2, we'll end up landing.  The point on spectrum will probably change over time as well depending on how many covid-19 infections we hear about over time.

Cigarbutt

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Re: Probability that covid will become endemic
« Reply #18 on: November 22, 2020, 05:42:49 AM »
...
 If the covid-19 reservoirs persist over time, even if it doesn't cause a material event on a global basis, would it impact behavior of some percentage of the population, e.g. not travel as much as they did pre-covid, not go to places with lots of people as much, etc.?
Maybe the behavior change will depend on the perceived probability of risk, and how readily available are the alternatives to taking risk, i.e. working from home, ordering everything online, etc.?  If the perceived risk is as high as it was (1) getting on 737 Max right after two crashes, maybe some would pick an alternative if available but if it as low as (2) driving a car, maybe people will accept.   Wondering where on the spectrum between #1 and #2, we'll end up landing.  The point on spectrum will probably change over time as well depending on how many covid-19 infections we hear about over time.
Interesting but difficult to handicap. Who knows what will happen but it's likely that our future will mostly look like before with the exception of changes in relation to a relative acceleration of previous trends, with some areas more ripe than others. i would say business travel and higher education are good candidates.
An interesting concept for the thought process is hysteresis (there are www opinions circulating now linking hysteresis with Covid-19). Hysteresis is used in many fields and i think it originated in pure physics but is also applied in 'softer' sciences, including finance. It has to do with an effect that persists after a temporary force or shock happens. Lingering effects of the virus will persist depending on the variables you mention but what will determine the outcomes is basically strongly tied to the condition of the host before. The hysteresis concept is also applicable for people who got sick (and getting sick) with Covid in relation to imaging changes seen in lung tissue. For Covid-19, it has been described (like just many cases of pneumonias) that patients who started to respond (mostly through their own intrinsic forces, supported by extrinsic measures) were showing deteriorating lung tissue anomalies on imaging, with a delay of a few days or even 2 to3 weeks before images started to improve, when the person actually felt fine and was often discharged. i think that's what Mr. Buffett said when he fundamentally discussed the risks related to waiting for a cheery consensus.