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So, the UK reported a new Covid strain. What's up with that? https://www.gov.uk/government/news/statement-from-chief-medical-officer-professor-chris-whitty-about-new-strain-of-covid-19
So, the UK reported a new Covid strain. What's up with that? https://www.gov.uk/government/news/statement-from-chief-medical-officer-professor-chris-whitty-about-new-strain-of-covid-19
First, let's take a look at the natural evolutionary 'behavior' of viruses in general before we come back to the Covid case in particular.
https://evolution.berkeley.edu/evolibrary/news/071201_adenovirus
As procreating organisms viruses are subject to natural selection, which influences the success of reproduction.
https://evolution.berkeley.edu/evolibrary/news/071201_adenovirus
As procreating organisms viruses are subject to natural selection, which influences the success of reproduction.
A virus needs an environment to reproduce (host) and means of transmission to new hosts. Only then is it evolutionary successful and the lineage continues.
Respiratory viruses are usually transmitted via droplets or airborne.
Respiratory viruses are usually transmitted via droplets or airborne.
The severity or harmfulnes of a pathogen is called virulence.
The more virulent a virus the higher its reproduction rate while exploiting the host's resources (cells get destroyed), which heavily impacts the health and wellbeing of the host.
The more virulent a virus the higher its reproduction rate while exploiting the host's resources (cells get destroyed), which heavily impacts the health and wellbeing of the host.
But simply over-exploiting a host doesn't work. When the host dies, the virus and all its descendents die.
If there was no transmission to new hosts, the lineage goes extinct.
So the virulence is directly affected by opportunities for transmission.
If there was no transmission to new hosts, the lineage goes extinct.
So the virulence is directly affected by opportunities for transmission.
Naturally the virus seeks a balance, where it can create offspring while letting the host be mobile enough to infect other hosts.
When selective factors change and transmission becomes less likely, the evolutionary pressure on a virus steers it towards less virulence.
When selective factors change and transmission becomes less likely, the evolutionary pressure on a virus steers it towards less virulence.
This is exactly what happens right now. Hygienic measures like hand sanitizing, masks (disputed), and distancing from other persons impede the transmission to new hosts.
All mutations leading to less virulence and as a result milder symptoms are favored under these conditions.
All mutations leading to less virulence and as a result milder symptoms are favored under these conditions.
Over the course of an epidemic the likelihood to find susceptible hosts (persons who can get infected) decreases as more and more people already got the disease and either have developed an effective immune response to the pathogen or died.
While in the beginning of an outbreak virulent strains are more competitive, less virulent variants succeed in the long run, when transmission to new hosts becomes unlikely. https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1003209#abstract0
In spring 2020 there were already several different strains of the coronavirus and new mutations are found regularly as we would expect from an organism with a high reproduction cycle.
https://nextstrain.org/ncov/global
The medial spot-light on one new strain is questionable at best.
https://nextstrain.org/ncov/global
The medial spot-light on one new strain is questionable at best.
When does a mutation become a new strain?
It's obviously up to the experts to determine the threshold, but the recently declared new strain appears to have an increased transmission rate of appr. 70% compared to the existing virus. https://www.dw.com/en/coronavirus-what-we-know-about-the-uks-new-covid-strain/a-56000831
It's obviously up to the experts to determine the threshold, but the recently declared new strain appears to have an increased transmission rate of appr. 70% compared to the existing virus. https://www.dw.com/en/coronavirus-what-we-know-about-the-uks-new-covid-strain/a-56000831
As far as we know the 'second wave' is part of a still ongoing epidemic. Therefore, we can assume that the virus is under increased selection pressure to evolve towards LESS virulence.
One note about the focus on case numbers: simply counting posive tests as 'cases' and deriving from that the severity of the situation is highly unprofessional (yes, I'm nice today).
Add to that the still unsolved mystery of the vanished flu.
https://twitter.com/RanBlessing/status/1339977137151995905?s=20
Add to that the still unsolved mystery of the vanished flu.
https://twitter.com/RanBlessing/status/1339977137151995905?s=20
God and nature with HIM are on our side. We have awesome immune systems.
Tread yourself with love and respect, eat healthy, breathe fresh air and be comfy as an anon.
Hope you enjoyed reading.
Merry Christmas!
Tread yourself with love and respect, eat healthy, breathe fresh air and be comfy as an anon.
Hope you enjoyed reading.
Merry Christmas!
