[CajunBMW]

Remember that exponential growth in regard to biology is different in that it deals with population growth of the organism. That is one needs to consider population growth as an increase by a constant multiple in each generation. For example a doubling. In biology one can have slow and fast exponential growth based on the life span of the organism. Thus there was and always will be exponential growth of a virus for example during the early phases. Certainly as resources become scarce for the virus (I.e. new hosts become hard to find due to quarantine for example) growth slows and you get the opposite and you see a deceleration or decay. In the absence of protective measures or making resources scarce, exponential growth will extend for a longer period of time. Thus masks, lock downs, quarantines can all affect the nature of spread and growth of the virus.

Many of the rates in general are tied to the R0 value of the virus. This friendly CoV that has us in its sights has a nice R0 value of around ~3, which is unfortunately higher than the flu and thus our new CoV is spread easier within us and thus in general has had a quicker doubling time at least in a naive population that takes no precautions. When protections have been put into place, the theoretic R0 value then is lessened and you get the Rt value, which you want to be 1 or less.

Cheers

[Soul_Glo]

So what happens after someone tests positive?

I have a friend who was told to take 10 days off work and return when feeling better. So she's back to work and in contact with the public.

Does one become asymptotic? Can they still pass it on? There have been some cases of 'long' illness or people getting it again.

Obviously she can't throw in the towel as she's a singleton with mouths to feed.

[robbiep]

Originally Posted by Soul_Glo

So what happens after someone tests positive?

I have a friend who was told to take 10 days off work and return when feeling better. So she's back to work and in contact with the public.

Does one become asymptotic? Can they still pass it on? There have been some cases of 'long' illness or people getting it again.

Obviously she can't throw in the towel as she's a singleton with mouths to feed.

You're infectious when you are 'shedding' live, viable virus particles (sneezing out, coughing, touching face and then surfaces, etc). That is generally in the early-mid part of the infection. At the end of infection, when you are recovering (if symptomatic) your immune system is on top of the infection, and you're shedding dead or dying virus particles.
Also, in the early-mid part of infection, you start shedding particles before you start feeling really ill - that's the real danger area, where you might feel just a bit 'under the weather' but still be putting out virus particles to a large number of people.

In non-symptomatic people like your friend, once she's gone past 10 days from the positive test she's highly unlikely to be still shedding viable virus particles.

Obviously that's not set in stone - there will be a tiny number of people who stop shedding virus particles after 3-4 days, and a similar number who carry on doing so for 3 weeks. But those are the outliers. The 10 days is designed to get the contagious stage clear in the vast majority of people.
As to 'long covid', I think the jury is still out on that one. I know one moderately fit person who's struggled to get back to fitness after it, and a couple of very fit people who've bounced back. More data needed, simply.

Re-infection ? There are a few dozen suspected cases of re-infection worldwide. In at least a few of them, the first infection was never confirmed by an antigen test at the time, it was a 'suspected covid', but the second infection confirmed by a test. So again, more data needed.

[thescouselander]

Originally Posted by Goneinsixtyseconds

I'm not engaging, your one voice against thousands of scientists is not going to change my opinion.

You do realise that scientists around the world are using the same technique to predict the trajectory of COVID don't you?

All I've done is outline a simplified model that can be used by anyone who knows a bit about maths to compare what's happening with projections made by the likes of Imperials model (which by the way is subject to much controversy even amongst scientists).

I don't t think it's a good idea to defer to authority on this without checking what they're saying and giving it some thought. Their track record on previous predictions has actually been not that good.

[robbiep]

Originally Posted by thescouselander

You do realise that scientists around the world are using the same technique to predict the trajectory of COVID don't you?

All I've done is outline a simplified model that can be used by anyone who knows a bit about maths to compare what's happening with projections made by the likes of Imperials model (which by the way is subject to much controversy even amongst scientists).

I don't t think it's a good idea to defer to authority on this without checking what they're saying and giving it some thought. Their track record on previous predictions has actually been not that good.

Yes, but you've put one chart (UK deaths) and assumed that everything is just that - and if the deaths number is 'reasonable', then everything is under control

But, as I've pointed out to you, the deaths number is a tiny fraction of it. For every 10 that die, you have 40-50 or so people taking up ICU spaces, some for a considerable period of time. You run out of those spaces, the mortality rate doesn't stay that low, it rockets up.
And that's without even considering the fact that people aren't coming forward with other health problems (early stage cancers, heart conditions, etc), which might be treatable now, but when they do come forward next year, treatment will be far less successful, and the mortality rate from those other illnesses will be higher.

So saying 'Covid deaths are really low' is a tiny fraction of the picture.

What you're doing is like looking through a keyhole at a photograph of London, seeing only a tree in the park as what you can see through that keyhole, and declaring that it's therefore a picture of a forest.

But hey, it's all good. You work in the NHS, seeing this lot. As long as the deaths chart is OK, it's all good.

Oh, wait ....

[Goneinsixtyseconds]

Originally Posted by thescouselander

You do realise that scientists around the world are using the same technique to predict the trajectory of COVID don't you?

All I've done is outline a simplified model that can be used by anyone who knows a bit about maths to compare what's happening with projections made by the likes of Imperials model (which by the way is subject to much controversy even amongst scientists).

I don't t think it's a good idea to defer to authority on this without checking what they're saying and giving it some thought. Their track record on previous predictions has actually been not that good.

I’m only skim reading your posts to be fair.

My quick assumption is that you are saying deaths would have dropped in a similar way had we not locked down, so it didn’t make any difference then and doesn’t now. If I’ve misunderstood, apologies.

And what I’m saying is that every country that had a steep downward curve locked down in some way right at the point it started downwards. I don’t believe that to be a coincidence. Your counter to that is that deaths dropped at exactly the same time as lockdown and that’s too early. But it’s not, because in most countries and in most cases, people were voluntarily socially distancing and following the rules and guidelines for a few weeks before countries made them law.

Even Sweden implemented social distancing guidelines, they just didn’t make them law. They could do that because on the whole I would consider their society more intelligent with fewer dicks and conspiracy theorists that think they know better.

[thescouselander]

Originally Posted by Goneinsixtyseconds

I'm only skim reading your posts to be fair.

My quick assumption is that you are saying deaths would have dropped in a similar way had we not locked down, so it didn't make any difference then and doesn't now. If I've misunderstood, apologies.

And what I'm saying is that every country that had a steep downward curve locked down in some way right at the point it started downwards. I don't believe that to be a coincidence. Your counter to that is that deaths dropped at exactly the same time as lockdown and that's too early. But it's not, because in most countries and in most cases, people were voluntarily socially distancing and following the rules and guidelines for a few weeks before countries made them law.

Even Sweden implemented social distancing guidelines, they just didn't make them law. They could do that because on the whole I would consider their society more intelligent with fewer dicks and conspiracy theorists that think they know better.

That's not quite what I'm saying. What I'm saying is as far as I can tell the growth rate did start decaying before lockdown was introduced (in fact peak infections may well have been pre-lockdown) - lockdown might well have made that decay even faster so the question becomes how much mitigation did lockdown give us Vs the high price we paid for it and does it make sense to do it again? I think this will be tested over the next few weeks if we compare the current projections of hospitalisations Vs the actual stats.

[Goneinsixtyseconds]

Originally Posted by thescouselander

That's not quite what I'm saying. What I'm saying is as far as I can tell the growth rate did start decaying before lockdown was introduced (in fact peak infections may well have been pre-lockdown) - lockdown might well have made that decay even faster so the question becomes how much mitigation did lockdown give us Vs the high price we paid for it and does it make sense to do it again?

Is there a reason you’re ignoring the fact that millions started working from home and social distancing a 2-3 weeks before the legal lockdown? Is it that you don’t believe it? Do you not consider it a possibility that that could be the reason for the growth rate slowing before dropping further after full lockdown?

[Sennen]

Met up with the BIL on Friday who is a GP and he seems to think as many of his colleagues do that the Virus is not as potent now as it was back at the start of the Pandemic.

What do people think?

Views from others rather than Gonein60seconds would be good.

[thescouselander]

Originally Posted by Goneinsixtyseconds

Is there a reason you're ignoring the fact that millions started working from home and social distancing a 2-3 weeks before the legal lockdown? Is it that you don't believe it? Do you not consider it a possibility that that could be the reason for the growth rate slowing before dropping further after full lockdown?

No, in fact I think maybe that's part of the answer. We're told there will be thousands of deaths without a severe lockdown. That's the bit I struggle with bacause by the looks of the timings the natural caution by the population seems to be pretty effective by itself. That caution and other measures are still there which is why I think it's possible we won't see the explosion of cases we saw in the first wave.

[robbiep]

Originally Posted by thescouselander

No, in fact I think maybe that's part of the answer. We're told there will be thousands of deaths without a severe lockdown. That's the bit I struggle with bacause by the looks of the timings the natural caution by the population seems to be pretty effective by itself. That caution and other measures are still there which is why I think it's possible we won't see the explosion of cases we saw in the first wave.

That caution isn't there any more.

Let's face it, most people are bored of it now. They've done their bit, they've clapped at 8pm on Thursdays, they now just want to go back to their normal lives. And it's been that way for a couple of months.

If that isn't blatantly obvious to anyone who does something as simple as walk into a supermarket, then nothing is going to convince them.

[JNW1]

Originally Posted by Sennen

Met up with the BIL on Friday who is a GP and he seems to think as many of his colleagues do that the Virus is not as potent now as it was back at the start of the Pandemic.

What do people think?

Views from others rather than Gonein60seconds would be good.

I'm not medically qualified so I'm not about to try to tell a GP he's wrong! I am however curious as to why he and many of his colleagues feel the virus is less potent now than it was a few months ago; I really hope they're right but what do they think has changed to reduce the risk - increased herd immunity?

[robbiep]

Originally Posted by JNW1

I'm not medically qualified so I'm not about to try to tell a GP he's wrong! I am however curious as to why he and many of his colleagues feel the virus is less potent now than it was a few months ago; I really hope they're right but what do they think has changed to reduce the risk - increased herd immunity?

To look at the potency of a virus, you need to look at what it is, and what makes it versatile - which is also what weakens it.

Viruses are a strand of RNA. We have DNA, which is 2 interlocking strands of RNA.

Imagine DNA like a ladder. Stable. RNA is a rope ladder - not stable.

When DNA is reproduced, it uses the second strand as a verification, to ensure it is copied correctly. RNA doesn't have that verification, so it mutates easily.

Ebola is the classic for a virus potency weakening over time (though ebola is a retrovirus, the basics are the same). Early stages, incredibly high mortality rate, 90-100%. Later stages of an outbreak, the virus is a lot weaker, and the mortality rate is regularly 10%, or even less.

Of course, the down side is that a virus can mutate to an extent that any vaccination developed against it no longer works - though the vaccine manufacturer can just 'tweak' the genetic code in the vaccine to protect against the new variant, rather than starting from scratch again (this is how the flu vaccine works)

[HighlandPete]

Originally Posted by JNW1

I'm not medically qualified so I'm not about to try to tell a GP he's wrong! I am however curious as to why he and many of his colleagues feel the virus is less potent now than it was a few months ago; I really hope they're right but what do they think has changed to reduce the risk - increased herd immunity?

My current understanding, the virus hasn't significantly mutated, to be less potent.

I'm wondering if some of the difference to the beginning of the first wave, is many older and vulnerable folk are still protecting themselves. Have done so all through the lockdown and continued to do so as restrictions were being lifted.

We've had all the talk of younger ones being the primary cause of the current spread. Now slightly changing, as more in the middle age group are showing up positive. That also starting to show as more hospital admissions. How long before we see more older and vulnerable folk getting infected? That's when we we could get something more like a repeat of the spring.

IMO, "self isolation" (never mind the current restrictions) by those of higher risk, due to being extra cautious, could be the difference between the first wave and what now follows.

[Goneinsixtyseconds]

Originally Posted by Sennen

Met up with the BIL on Friday who is a GP and he seems to think as many of his colleagues do that the Virus is not as potent now as it was back at the start of the Pandemic.

What do people think?

Views from others rather than Gonein60seconds would be good.

Not sure why I’m not allowed to respond, I’ve not been overly dramatic about it and I think the below is pretty balanced.

I’ve said before what my view is. I do think it’s killing less people here, but I don’t think the virus itself is less potent. I think, like other countries with lesser death rates, our social distancing and mask wearing is reducing the viral load and that has been shown to reduce serious cases. If we let our guard down I think it will make a return. Luckily the majority are happy to follow rules up to a certain point. We just think we’re bad as a country because those that don’t want to follow the rules make more noise and fuss.

The science I’ve read says that coronavirus’s don’t mutate and change as quickly as other viruses, so the thoughts in the research I read were that they felt it was much more likely our actions had created the improved outcomes, not the virus itself.

To me, that all makes perfect sense, and is why in countries where it has been harder to distance and follow rules, such as Brazil and India, it hasn’t become less deadly.

The question for me, is if it carries on as now and becomes more widespread, will our mask wearing and social distancing still mean the viral load remains low. Hopefully it will and deaths won’t rise like the number of cases.

It seems to me that we’re still walking a tightrope where it could go either way. Hopefully it will head the way we all want it to. I just don’t believe it will happen without our continued vigilance.

[Sennen]

Originally Posted by JNW1

I'm not medically qualified so I'm not about to try to tell a GP he's wrong! I am however curious as to why he and many of his colleagues feel the virus is less potent now than it was a few months ago; I really hope they're right but what do they think has changed to reduce the risk - increased herd immunity?

I didnt go into any in depth detail with him, unlike some others on here I dont profess to be an expert and I feel I have neither the brains or the knowledge to dismiss any ones viewpoint completely.

I must say I am erring more and more to getting back to normal ASAP, there was a lady on QT last week who thought that maybe we should all go back to a normal lifestyle whilst properly protecting our Very Vulnerable and get ourselves on the road to some sort of herd immunity.

Just the ramblings of a thick old builder, I am sure the Oracle will be along shortly to put us in our place

[HighlandPete]

Originally Posted by Sennen

I didnt go into any in depth detail with him, unlike some others on here I dont profess to be an expert and I feel I have neither the brains or the knowledge to dismiss any ones viewpoint completely.

I must say I am erring more and more to getting back to normal ASAP, there was a lady on QT last week who thought that maybe we should all go back to a normal lifestyle whilst properly protecting our Very Vulnerable and get ourselves on the road to some sort of herd immunity.

Just the ramblings of a thick old builder, I am sure the Oracle will be along shortly to put us in our place

I watched QT and could follow her argument, and the guy on the panel with his "6-point" plan.

Where I found both arguments hard to grasp, was how a different course can be implemented. I'm sure that is the government's problem as well.

Does it mean completely putting all the (us) older folks and the vulnerable into a full lockdown again, isolating us from all social and 'normal' activities?

One immediate problem is separating grandparents from the younger family. Both for day to day essentials, like child care, school runs, etc., on which support many families can earn a living and survive. Plus the social interactions. I've already got an aunt going stir-crazy, as she is separated from friends and family.

My wife had an update letter last week from Scot Gov, as she's in the vulnerable group. We are not far off lockdown conditions as it is, if we really follow the current guidelines, even with shielding being paused.

[Sennen]

Originally Posted by HighlandPete

I watched QT and could follow her argument, and the guy on the panel with his "6-point" plan.

Where I found both arguments hard to grasp, was how a different course can be implemented. I'm sure that is the government's problem as well.

Does it mean completely putting all the (us) older folks and the vulnerable into a full lockdown again, isolating us from all social and 'normal' activities?

One immediate problem is separating grandparents from the younger family. Both for day to day essentials, like child care, school runs, etc., on which support many families can earn a living and survive. Plus the social interactions. I've already got an aunt going stir-crazy, as she is separated from friends and family.

My wife had an update letter last week from Scot Gov, as she's in the vulnerable group. We are not far off lockdown conditions as it is, if we really follow the current guidelines, even with shielding being paused.

It would be incredibly difficult to implement Pete.

My elderly mother has lived with me for the past couple of years and it is a constant concern but she really has had enough now and sort of takes the attitude that this is no way to live.

There is no easy way out of this and certainly no single route that is going to please and suit everyone.

Not sure what the current vaccine situation is but it would appear there is nothing on the horizon. I do ask myself how much more of this the British Public can cope with. I suspect that the vast majority of us will knuckle down and do the right thing if another total lockdown follows but i get the impression that patience is starting to wear thin especially in my sons generation and you cant really blame them.

[RobUK]

Originally Posted by robbiep

You're infectious when you are 'shedding' live, viable virus particles (sneezing out, coughing, touching face and then surfaces, etc). That is generally in the early-mid part of the infection.

Add to that heavy breathing, singing and talking (aerosol transmission) which quite a few sources now think could be the primary transmission method (rather than droplets or fomites). Example from the British Medical Journal. The popular media haven't really pushed this idea though, but I could have missed that as I try to steer away from the 'doom' news

[HighlandPete]

From my perspective, a vaccine is possibly a long way off for the vulnerable groups.

From what I read and hear, what may get through all the testing and approval for the more healthy in society, will be a much bigger challenge for all groups.

[RobUK]

Originally Posted by Sennen

Met up with the BIL on Friday who is a GP and he seems to think as many of his colleagues do that the Virus is not as potent now as it was back at the start of the Pandemic.

What do people think?

Views from others rather than Gonein60seconds would be good.

There seem to be reports that the average age of people contracting the virus has dropped and is much lower than it was at the start of the outbreak, therefore younger 'healthier' patients means fewer deaths.

[CajunBMW]

I would like to clarify a couple of the comments. You are correct that we have a double stranded DNA genome but both strands can be coding and thus both are important. It is two strands of DNA not RNA the sugar on the nucleic acid dictates DNA vs RNA. We have DNA that is made to RNA that is the made to protein.

DNA as a double stranded molecule is not necessarily more stable that RNA because it is single stranded. As a molecule DNA is not more stable than RNA. The reason one generally thinks about RNAs being less stable is because of RNAses on our fingers, etc that degrade RNAs.

In regards to stability of the genetic coding the reason we are stable and have a stable DNA genetic code is not because of two strands, but because our human DNA polymerase doesn't make many errors and because we have a robust proofreading mechanism that does fix mistakes. Mistakes as you point out are rare and are of course the root cause of many cancers.

Viruses come as DNA viruses and RNA viruses. Many of the DNA viruses have similarly good polymerases and don't favor lots of mutations unless needed. These viruses can be further divided into double stranded DNA viruses, double stranded RNA viruses, single stranded DNA and or RNA viruses. There are even some that are both single and double stranded. It is these differences and or similarities that can be exploited for drugs and treatments.

So an example of virus with lots of mutations is HIV which is a retrovirus. Ebola is a filovirus and a very different type of virus. HIV does have a very high mutation rate but evolutionarily that is desirable. The new CoV is a large double stranded RNA virus and it does posses a fairly robust polymerase.


Viruses do adjust to the human population and in general with time do lose pathogenesis but it can take time like decades (at least usually). Coronaviruses and Herpesviruses are really good examples of virus that adapted to us and have less severe disease over time (present CoV and MERS-CoV aside). Ebola is not good example since it is only one of the filoviruses that we colloquially call Ebolaviruses. Some of the filoviruses are more deadly some are a lot less deadly or not deadly at all.

Lastly you are correct about viruses mutating and that can be a real problem for vaccine development. For the Moderna and Pfizer vaccines since they are mRNA vaccines they can be easily tweaked. The flu as is presently made starts with real virus each year and involves lots of chickens and eggs, so that uses a different process. Even the Oxford/AZ which uses Adenovirus vectors can be reasonably easily modified should changes in the spike proteins develop (I.e. escape mutants).

Cheers