Author Topic: Herd Immunity  (Read 819 times)

Offline zetlander

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Herd Immunity
« on: Thursday 15 October 20 22:30 BST (UK) »
Keep hearing this expression - surely the only time we may get 'herd immunity' is when every member of the herd has had Covid and hopefully then they are immune to the virus??

Offline Rena

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Re: Herd Immunity
« Reply #1 on: Thursday 15 October 20 22:52 BST (UK) »
I heard a discussion today and Herd Immunity probably won't happen because it seems some people are catching the virus a second time, which indicates one of two things (or both things).  (a) the virus has mutated, or (b) immunity only lasts a short period of time.   
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Offline Kiltpin

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Re: Herd Immunity
« Reply #2 on: Thursday 15 October 20 23:27 BST (UK) »
There is also a (c) Long Covid. Where someone contracts covid, it goes through its cycle and then goes into hibernation. It then comes back (not as strongly) a while later.   

There is some debate as to whether people really get a second contraction, or have Long Covid. And if it can come back once, can it come back again and again? 

Roll on a vaccine. 

Regards 

Chas
Whannell - Eaton - Jackson
India - Scotland - Australia


Offline BushInn1746

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Re: Herd Immunity
« Reply #3 on: Friday 16 October 20 05:39 BST (UK) »
I heard a discussion today and Herd Immunity probably won't happen because it seems some people are catching the virus a second time, which indicates one of two things (or both things).  (a) the virus has mutated, or (b) immunity only lasts a short period of time.   

World Health Organisation (WHO)
Variant analysis of SARS-CoV-2 genomes
https://www.who.int/bulletin/volumes/98/7/20-253591/en/

According to WHO (in the above link, which mentions strains, mutations & variants) if you try and treat Covid-19 it mutates and can potentially become more virulent:-

"Community transmission of the virus, as well as anti-viral treatments, can engender novel mutations in the virus, potentially resulting in more virulent strains with higher mortality rates or emergence of strains resistant to treatment.15 Therefore, systematic tracking of demographic and clinical patient information, as well as strain information is indispensable to effectively combat COVID-19."

15 is a Footnote.
15. Sanjuán R, Domingo-Calap P. Mechanisms of viral mutation. Cell Mol Life Sci. 2016 12;73(23):4433–48. http://dx.doi.org/10.1007/s00018-016-2299-6 pmid: 27392606 [27392606 is a link to this ... ] http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=27392606&dopt=Abstract
 ----------
Perhaps why Scientists have already said we have got to adapt and learn to live with it?

Continue with Wash Hands, Socially Distance and Mask protection

Mark

See also research by the Quadram Institute, England
https://quadram.ac.uk/covid-19-genome-sequencing-in-norfolk-helps-manage-coronavirus-outbreaks/

Offline pharmaT

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Re: Herd Immunity
« Reply #4 on: Friday 16 October 20 08:51 BST (UK) »
Keep hearing this expression - surely the only time we may get 'herd immunity' is when every member of the herd has had Covid and hopefully then they are immune to the virus??

For herd immunity 70-80% of the population would have to be immune, although preferably more.  That's why vaccines are generally considered the only safe way to achieve this.  As Rena says there is a good chance that any immunity is not long lasting, although it could be a situation like rubella when a proportion of the population never achieve immunity but others can.
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Offline trystan

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Re: Herd Immunity
« Reply #5 on: Friday 16 October 20 09:07 BST (UK) »
The thing is, we now live in a "world population", not just in our own country in a sense. There is so much free movement of people that effectively the herd immunity would have to be the world's population? Or I may have misunderstood it.
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Offline BushInn1746

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Re: Herd Immunity
« Reply #6 on: Friday 16 October 20 09:11 BST (UK) »
The Lancet

Google Summary
3 days ago — SARS-CoV-2=severe acute respiratory syndrome coronavirus 2. This case report adds to rapidly growing evidence of COVID-19 reinfection, in which viral genomic sequences were used to confirm infections by distinct isolates of SARS-CoV-2.

https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30783-0/fulltext

Added:

"Thus, reinfection cases tell us that we cannot rely on immunity acquired by natural infection to confer herd immunity; not only is this strategy lethal for many but also it is not effective."

Offline pharmaT

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Re: Herd Immunity
« Reply #7 on: Friday 16 October 20 09:13 BST (UK) »
The thing is, we now live in a "world population", not just in our own country in a sense. There is so much free movement of people that effectively the herd immunity would have to be the world's population? Or I may have misunderstood it.

Within our country and those most likely to travel here.  Yes I'd have thought so
Campbell, Dunn, Dickson, Fell, Forest, Norie, Pratt, Somerville, Thompson, Tyler among others

Offline Guy Etchells

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Re: Herd Immunity
« Reply #8 on: Friday 16 October 20 09:39 BST (UK) »
The thing is, we now live in a "world population", not just in our own country in a sense. There is so much free movement of people that effectively the herd immunity would have to be the world's population? Or I may have misunderstood it.

If you are thinking of getting rid of the virus completely you are correct, for most countries herd immunity is a step towards controlling a disease, i.e. keeping the spread limited to controllable levels.
In which case a countrywide immunisation programme suffices.
This does not wipe out the virus or disease but reduces the numbers liable to require intensive care.
An additional benefit of vaccination is it often gives a longer lasting immunity than catching and recovering from the virus/disease does.
Cheers
Guy
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